Monday: Benchmark 3 (a study guide has been sent home with students)
Tuesday: Plants Baseball Choice Board
Wednesday: BINGO, choice board
Thursday: plant vocabulary quiz, choice board
Friday: NO SCHOOL FOR STUDENTS: teachers inservice
Posted by: Team 7.2 Science
| @ February 28, 2010 10:05:30 PM EST ( ) |
Monday: No School, President's Day
Tuesday: Ecology Test (Part 2), Plants Pre-test
Wednesday: Ecology Post Test, Plants notes- there are MANY new vocabulary words, so it is very important that students make flash cards, etc. to study.
Wednesday is also the day of the 100+ stamp field trip.
Thursday: notes, continued. Plant vocab BINGO
Friday: Life Cycle Drawings
Posted by: Team 7.2 Science
| @ February 15, 2010 3:18:50 PM EST ( ) |
Monday: Oh Dear! Review Quiz taken on Friday.
5th Block: Take quiz and turn in Ecology Review.
Tuesday: Notes: Cycles in Nature. Notes are posted below:
Cycles in Our Ecosystems
Anything that has mass and occupies space is matter. This matter must be used over and over again in our closed ecosystem, we call this recycling. We will discuss a few of the very important cycles life depends on.
The Water Cycle
The movement of water among the oceans and our atmosphere, and the movement of fresh water (lakes, rivers, and streams) and our atmosphere make up the water cycle. There are several parts we will consider of the water cycle.
Precipitation
Water moves from the atmosphere to the land or bodies of water as precipitation (rain, snow, sleet, and hail). About 91 % of the water falls into our oceans, the rest falls on lakes, rivers, ponds, streams and the land as fresh water. Remember: fresh water does not necessarily mean it is clean water, it simply means it is low in salt content. Think of ocean water as salt-water.
Evaporation
When water goes from the bodies of water on the Earth back into the atmosphere, evaporation has occurred. This cycle is driven by the energy from the sun. When water vapor cools as it undergoes the process of condensation. Condensation is the process of water going from the gas phase into the liquid phase. In order for water to condensate, the moisture must have some form of particulate to attach to. This particulate can be in the form of dust, smoke, or other forms of pollution as well as solid surfaces. When condensation occurs in the atmosphere and falls back to Earth we again have precipitation. This is why it is called the water cycle.
Ground Water
As the water falls to the Earth, some of it falls onto the land. Some of the water seeps into the ground and enters underground caves, rocks with small pores and is often stored there. This water in under ground is called ground water. Ground water may stay in the Earth for hundreds to thousands of years. It can also slowly flow through the passages underground. Some ground water may drain into rivers, streams, form springs, or enter into the ocean.
Water and Life
All organisms require water to survive. Humans are about 70% water. RECALL: water transports wastes from our tissues and cells. Water also regulates our body temperature when we sweat and the sweat evaporates (this cools our body). Plants also need water in order to survive (they are living organisms). When water is returned from organisms back into the environment or atmosphere, the process is called transpiration. If there was not any water on Earth, there would not be any life.
The Carbon Cycle
Carbon is in all living organisms. The movement of carbon from the environment into living things and back into the environment again is called the carbon cycle.
Photosynthesis (This should be a review)
Photosynthesis is the process by which carbon cycles from the environment into living organisms. During photosynthesis, plants use carbon dioxide from the air to make sugars. Most animals get the carbon they need by eating the plants (when they eat the plants they are taking carbon into their body to make molecules that will contain carbon.
Respiration (This should be a review).
Carbon returns to the environment during respiration. RECALL: Respiration occurs in both plants and animals. When respiration occurs, sugar molecules are broken down to release energy. Carbon dioxide and water are released as by-products. Remember: we exhale carbon dioxide and water.
Decomposition
The breakdown of dead materials into carbon dioxide and water is called decomposition. Recall: Bacteria and some fungi decompose dead materials. When these organisms decompose the dead material, they are returning the carbon to the environment.
Combustion
The carbon in coal, oils and natural gas returns to the atmosphere when we burn the fuels. They release carbon dioxide into the environment when they are burned. The process of burning fuel is called combustion. We use combustion to heat our houses, run our vehicles, and make electricity.
The Nitrogen Cycle
The movement of nitrogen from the environment to living things and back is called the nitrogen cycle. About 78% of the Earth’s atmosphere is nitrogen gas. Most organisms cannot use the atmospheric nitrogen (nitrogen in our atmosphere), but there are specific types of bacteria that convert atmospheric nitrogen into a form of nitrogen plants can take in and use. These bacteria are carrying out nitrogen fixation. After the plants get the nitrogen into their tissues, other organisms consume the plants and take the nitrogen into their body to be used.
Bacteria in the soil perform the final step of the nitrogen cycle. These bacteria are of a different species than those that carry out nitrogen fixation. These bacteria break down dead organisms and animal wastes. This process produces nitrogen gas, which is returned to the atmosphere.
SECTION 2
Ecological Succession
Succession is defined as the gradual development of a community over time. There are two types of succession. The first type we will discuss is primary succession and the second type is called secondary succession.
Primary Succession
Primary succession occurs when a community develops on an area where living organisms did not live before. A bare rock can be an example of a location where living organisms had not grown in the past. We will use this as our example of primary succession.
If we observed a bare rock over many years, we would have noticed that the first life forms to begin growing on the rock are lichens. The acids produced by the lichens begin to weather or break down the rock. These first organisms are called pioneer species. The lichens that die over time and small fragments of rock that begins to break away from the larger rock become soil. The next organism that becomes established are mosses, which may be dropped from an animals paw, hoof, or other part of their body or the moss may have spores that are blown onto the area by the wind. Once some of the mosses and lichen begin to die off, the soil become deeper and small species of grasses and flowers can begin to grow.
The grasses and flowers may get to the area by wind blowing them onto the site or animals that have eaten the seeds of the grasses and flowers may deposit them on the site. As time passes and more plant material accumulates from plants, mosses and lichens dieing, the soil continues to get deeper. This deeper soil provides a “root bed” for larger plants like small trees and shrubs.
After many more years of soil formation, larger trees can become established onto the site and the area ends up being a forest. Remember that new plants arrive on an area by the wind blowing the seeds or spores and animals can carry the seeds onto the site. Many seeds that are eaten by birds are spread to new areas after the seed has passed through the digestive system of the bird. Many seeds actually cannot germinate unless they pass through the digestive system of an organism.
Secondary Succession
This is very similar to primary succession, but the area has once had an existing community on it. The community or ecosystem may have been destroyed by fire, other natural disasters or by the interference of humans. A good example would be an area that once had a forest on it, but the forest was removed to make farmland and the farmer stops farming. Secondary succession begins the first year the farmer stops farming. During the first year, many weeds like crabgrass and broom sedge (a form of grass) grows on the field. During the second year, new plants begin to grow from the seeds that have blown into the field or have been carried into the field by an animal. In five to fifteen years (depending on the location) small trees like pines begin to grow. After many years of the pines growing, hardwood trees begin to grow under the pines and as the pines die and fall to the ground, the hardwoods receive more sunlight in which to grow. After 80 to 100 years you will end up with a mature hardwood forest (oaks, hickories, some maples, sweetgum, and other hardwoods) and a few pines on the drier ridges in the area.
Does succession end? Well, the answer is yes. What type of ecosystem is the end result? It depends on the climate (how much precipitation and the temperatures the area has over time). In the southeast United States, we end up with a mature hardwood forest. In the northern United States and southern Canada, you would find the Coniferous Forest (Pines, Spruces and Fir Trees). If you had an area with relatively high temperatures on average and low precipitation, you would end up with a desert. If the area had relatively low temperatures and low precipitation, you may have Tundra.
Wednesday: Vocabulary Quiz, Brainpop
Thursday: Test Review
Friday: Ecology Test
Posted by: Team 7.2 Science
| @ February 6, 2010 9:52:17 PM EST ( ) |
Interactions of living Things
SECTION 1
When we look closely at our surrounding environment, we find that everything (all organisms and object) is connected in one or more ways. If one of the connections is broken, the impact is often detected by observing many different organisms and what happens to organisms when a “connection” is manipulated. Most of the time we look at organisms in our environment and only “see” only organisms that eat other organisms. We seldom pay much attention to some of the other factors we will learn about during our study of the environment.
The living organisms in the environment are dependent on other living organisms for food sources and survival. We are going to learn that these interactions form what is known as a food web(s). Scientist that study these interactions within the environment and we call these scientists ecologists. We must ask ourselves “what is ecology?” and we will find out that ecology is the study of the interactions between organisms and their environment.
The Environment
The environment is made of two things, nonliving things and living things. We have special terms for these. Nonliving things are referred to as abiotic; these include rocks, weather factors, the type of soil, the amount of light, and the temperature. The living part is referred to as biotic. Biotic factors include all the living organisms that live together and interact with each other.
Practice: Consider a pond, list as many biotic and abiotic factors that someone may find at a pond. Did you say: biotic may include the fish in the pond, birds around the pond, maybe a beaver or muskrat, the small organism’s fish feed on, aquatic (water) plants, maybe algae? What about abiotic: you may have listed the mud on the bottom of the pond, the rocks in and around the pond, the water, the temperature of the water, the amount of sunlight the pond gets, the shade if there are trees bordering the pond? You may have other biotic and abiotic factors listed, but the main idea is to learn what the terms biotic and abiotic means and give examples of the terms.
The Organization of an Environment
RECALL: remember the organizational levels of organisms? Cells make up tissues, tissues make up organs, organs make up organ systems and organ systems make up organisms.
The environment also has levels of organization we can discuss. The first level contains individual organisms. The second level is similar organisms that form populations. The third level is different populations forming a community. The fourth level is the community and its abiotic factors forming an ecosystem. And finally, all of the different ecosystems make up the biosphere. Bio means life.
We must understand the definition of each level in order to understand how they are all connected.
Populations – A population is a group of individuals of the same species that live together in the same area at the same time. Example: All of the white-tailed deer in Walker County. These deer compete with each other for resources (food, water, space, etc).
Communities - A community consists of all of the populations of different species that live and interact in an area. The different populations will be depending on each other for food, shelter and other things. All of the various animals and plants in an area make up the community in a given area.
Ecosystems – An ecosystem is made up of all the communities found there as well as the abiotic factors in the area. Ecologists that study ecosystems must look at the interaction between living organisms and the nonliving objects in order to get a good understanding of how the ecosystem functions.
Biosphere – The biosphere is the portion of the Earth where we find life. The biosphere extends to the deepest parts of the ocean to very high in the atmosphere, where tiny insects and plant spores drift. The biosphere includes all ecosystems.
Section 2 – Living Things Need Energy
In order for living things to survive, they must all have energy available to them. Organisms use energy to carry out daily activities, heal themselves if they become hurt, and reproduce offspring. Organisms can be grouped into three categories based on how they obtain their food. These three categories are producers, consumers and decomposers.
Producers – These organisms are capable of producing their own food, most often by carrying out photosynthesis (plants and algae). In the last 15 years scientists discovered that there are organisms producing their own food from deep ocean vents where the element sulfur is released from the Earth. There are bacteria that capture the sulfur and make their own food from it and the bacteria serve as food for other organisms that survive at these great depths. On land, (terrestrial environment) plants carry out photosynthesis and are the main producers. In our oceans, algae that carry out photosynthesis are the main producers.
Consumers – Consumers are organisms that cannot produce their own food. Consumers must eat other organisms in order to get food. We will look at several types of consumers. These include herbivores, carnivores, omnivores and scavengers.
Herbivores – these consumers eat plants for their food source. Examples: cows, bison or buffalo, grasshoppers, muskrats, and some rodents (groundhogs). Carnivores – these consumers feed upon other animals, so they eat meat. Omnivores – these consumers feed upon both plant and animals as their food source. Scavengers – scavengers are animals that feed on bodies of dead animals. Example: Turkey vultures (some people call them buzzards) feed on dead animals. In aquatic ecosystems, crayfish (crawdads), snails, worms and crabs can be considered scavengers.
Decomposers
Decomposers are the organisms that obtain their energy by breaking down the remains of dead organisms. Bacteria and many fungi can be considered decomposers. Decomposers are very important to an ecosystem because they return the dead organism’s nutrients back into the ecosystem so other organisms can benefit from the nutrients. You could think of decomposers as natures “recyclers”.
Food Chains and Food Webs
A food chain is a “flow chart” that shows how energy flows from one organism to another and through the ecosystem. A food chain shows what organism another organism consumes. Example: Imagine there is some clover growing on the ground and a mouse is eating the clover. A snake slithers from the nearby tall grass and catches the mouse and eats the mouse, but before the snake gets back into the tall grass to hide a hawk swoops from the sky and captures the snake and eats the snake. The food chain would be represented by: clover > mouse > snake > hawk.
Most food chains can overlap because many organisms feed on several different foods. When food chains overlap, we say there is a food web. A food web shows us many pathways that energy can flow through an ecosystem. The energy always flows in a one-way direction in the ecosystem. Energy an organism does not immediately use is stored in the organism’s tissue(s). Only the energy that is stored in an organism’s tissue(s) can be used by the next consumer. This leads us to the question of “how much energy can be passed from one consumer to the next consumer?” We must look at food pyramids to understand this concept. Some people refer to these as energy pyramids.
Energy Pyramids
Imagine the shape of a pyramid. The base is very wide compared to the pointed tip. Now imagine the lowest area near the base is where producers are located. The next level up the pyramid you will find a consumer that feeds on the producer represented at the pyramids base. This consumer is called the primary consumer (meaning the first consumer of the food chain the pyramid is representing). The next level would be the secondary consumer meaning the second consumer on the chain, the following level is the tertiary (meaning third) consumer. With our previous example, the clover is the producer and the base level of the pyramid. The mouse is the primary consumer, the snake is the secondary consumer, and the hawk is the tertiary consumer. Most energy pyramids only have four or five levels. REMEMBER: only the energy stored in the tissues of an organism can be transferred to the next level.
As you proceed from one level to the next higher level, the energy that can be transferred becomes less and less. As a rule, only about 10% of the energy can be transferred from one energy level (pyramid level) to the next higher level.
Example: if the clover provided the mouse with 1,000 calories, the snake could only gain about 10% of these when it consumed the mouse (100 calories), when the hawk consumed the snake, it could gain about 10 calories. In other words only 10% of the energy is available from one consumer to the next higher consumer.
The energy pyramid also gives us some other information. The wide base represents a larger number of organisms than the next level. So there must be more clover plants than mice and more mice than snakes and more snakes than hawks as we go up the pyramid. If it were the opposite, there would not be enough organisms to support the next level with sufficient calories (food) so the food chain would collapse.
Habitat and Niche
These are two terms that are important to an ecologist because it gives an indication of the food types available for an organism and what the function of the organism is in the environment. An organism’s habitat is the environment in which the organism lives (forest, desert, swamp, marsh, etc.) An organism’s “role” or way of life is the organism’s niche. An organism’s niche includes its habitat, its food, its predators, the organisms it competes with for survival. The niche can also include the abiotic factors like temperature, light, and moisture.
SECTION 3
Types of Interactions
Within nature the interactions between populations of different species affect the population sizes. (Some organisms regulate the population of others by feeding “preying” on other organisms). Example: in the arctic tundra, there are small rodents (similar to hamsters) called lemmings. The lemmings are eaten (preyed upon) by arctic foxes and other animals. The animals that prey on lemmings help control the lemming population size.
Having Offspring
In nature, most organisms have more offspring than can survive. Example: A fish may lay hundreds of thousands of eggs, but all of the eggs will not hatch. Some of the eggs may be preyed upon before they hatch. In most situations, the population of organisms remains fairly constant in nature unless rare conditions occur that supplies more food for a larger population than normal.
Limiting Factors
Populations of organisms cannot continue to get larger and larger (grow) due to limited food, space, water, and other resources the organism needs. These resources (biotic and abiotic) serve as limiting factors. (Limiting factor – a resource that is needed, but is in limited supply). Any needed resource can become a limiting factor if the organism cannot get enough of the resource to survive.
Carrying Capacity
The largest population that an environment can support over a long period of time is known as carrying capacity. When populations grow larger than the carrying capacity, limiting factors occur and some of the population will die due to limited resources.
If the limiting factors continue to decline, the population must decline also. As soon as the environment “improves” and the limiting factors return to “normal”, the population size will also increase and return to “normal.
Interactions Among Organisms
Populations have interactions between their own species and other species in the environment. Example: Grey squirrels interact when they feed in the same area, so this is an example of the same species interacting together. Grey squirrels may also interact with different species. Example: an Great Horned Owl may see a Grey Squirrel as food and capture and eat the squirrel. Many interactions such as this occurs everyday in the environment(s) that are on Earth. These interactions are necessary for life to continue. Interactions may take the form of competition for food, space, mating partners, water, and living space for example. Interactions may also take the form of predator prey relationships (one organism capturing and eating another organism).
Competition
Again populations in a community can have competition among the same species, or you can also find competition between different species. An example of competition between different species could be Grey squirrels and White-tailed deer competing for the available acorns for the main food source at times of the year. Remember competition can be in the form of organisms competing for the same space, food, shelter, and even sunlight (especially plants). So we must remember that competition can be within the same species as well as between different species.
Predators and Prey
An organism that is eaten by another organism is called prey. The organism that is eating is called the predator. When a fish eats a worm, the fish is the predator and the worm is the prey.
Predator Adaptations
In order for predators to survive, they must be able to capture prey. Some predators run fast in order to accomplish this, others may be excellent at hiding, others may be excellent stalkers to capture prey. Different predators have different methods and adaptations to capture their prey.
Prey Adaptations
Prey organisms have also adapted to keep from being eaten. Methods prey have to avoid capture is to run fast, stay in groups, and some have adapted camouflage methods. Some prey are poisonous to predators and so they are not eaten. Some preys have bright colors that warn prey that they should stay away. Examples: fish often stay in small schools which give the illusion that they are one large organism and this can scare predators away. Antelopes and buffalo remain in herds for protection. When you have many organisms, they all serve as lookouts because each organism will be using sight, hearing, and smell to avoid being eaten. Some prey hide by using camouflage, some look like leaves, some may resemble sticks, and some may look like tree bark.
Symbiosis
Symbiosis is a close, long term association between two or more species. The individuals in a symbiotic can benefit from, be unaffected by, or be harmed by the relationship. Often one species lives on or in another species when a symbiotic relationship occurs. There are three specific types of symbiotic relationships in nature. These are 1) mutualism, 2) commensalisms, and 3) parasitism.
Mutualism
A symbiotic relationship in which both organisms benefit is called mutualism. Example: we have a species of bacteria that live in our intestines that produce certain vitamins for us and the bacteria get nutrients form the food we eat. Humans and the bacteria benefit from the relationship.
Commensalism
Commensalism occurs when there is an symbiotic relationship in which one organism benefits and the other is unaffected by the relationship. An example is a fish that rides under a shark waiting on the shark to eat something and get the “tidbits” the shark loses. These fish are called remora fish. The shark is not harmed in the relationship.
Parasitism
In this symbiotic relationship, one organism benefits and the other organism is harmed. The organism that benefits is called the parasite and the organism that is harmed is called the host. The parasite gets nourishment from its host and the host will become weak over time and often so weak the host dies. Examples of parasites are ticks, tapeworms, leeches, and many organisms called roundworms.
Most parasites do not kill their host or they would have to find another host to survive within. If the parasite killed the host organism it may not be able to find another host to live in or on and the parasite itself may die.
Coevolution
Coevolution is a long term change that takes place in two species because of their close interactions with one another. Coevolution sometimes occurs with herbivores and the plants they feed on. The acacia tree and a species of ant have evolved together. The tree produces a form of food for the ant and provides a place for the ants to live and the ants protect the tree by attacking herbivores that try to feed on the tree.
Coevolution and Flowers
Some of the most amazing examples of coevolution are between their pollinators. A pollinator is an organism that carries pollen from flower to flower. Examples of pollinators: hummingbirds, butterflies, and bees. These organisms gather nectar from flowers and in the process they get pollen on themselves and when they visit the next flower, they leave some pollen on the flower and this helps fertilize the flower to produce fruit. The pollinators are attracted to the flowers by color, scent, and the nectar. When the pollinator places its head into the flower for the nectar, some of the pollen there attaches to the pollinator and is transferred to the next flower the pollinator visits.
Posted by: Team 7.2 Science
| @ January 24, 2010 2:48:17 PM EST ( ) |
Monday: MLK Holiday- no school
Tuesday: Go over Bacteria, Protist, Fungi quiz
correct missed items for partial credit
Finish Diversity of Life notes: plants and animals.
Wednesday: Organelle Trail in the Computer Lab
ORGANELLE TRAIL
Part 1: First Duties
1. Get your assigned partner (Most of you will be working with a partner because it is much safer for law enforcement to work in pairs! However, some will work on the easier cases alone.)
2. Get your assigned organelle/structure (This will be provided in your briefing - during class!)
Organelle: __________________________________
Part 2: Gather Your Facts
To complete your poster (and find your suspect!), you will need to gather facts on the trail! As you gather your facts, record the information on your FACT SHEET. You will need to know the following:
1. CRIME: What has this organelle done?
• Why is this organelle "wanted"? In other words, what does it do for the cell? Or, what is the organelle’s function?
2. PHYSICAL DESCRIPTION: What does the organelle look like?
• Provide a description and an actual picture. The picture can be a mug shot (printed picture) or a sketch from a sketch artist (hand drawn).
3. LOCATION: Where should we look for the organelle?
• Which of the following types of cells is this organelle found in? Make sure that you have explored, bacteria – Archaebacteria and Eubacteria, Protists, Fungi, Plants and Animals.
• Where is the organelle located in the cell? (By other specific organelles? By the cell membrane? Floating in the Cytoplasm?)
Part 3: Trail Sites
You will need to follow the “cyber” trails to find information about your wanted organelle. You do not need to visit each website. However, each website will offer information to help you gather your facts!
1. Life Science Safari - http://vilenski.org/science/safari/index.html
Travel with Safari Sally in search of different types of living things and the organelles/structures that are inside their cells. Each kingdom is described and the organelles in the cells of each kingdom are included. The functions of all of the organelles are briefly described here as well.
2. Cell Structures and Functions - http://www.tvdsb.on.ca/westmin/science/sbi3a1/Cells/cells.htm
This website is a great way for students to discover the functions of cells and cell parts. It compares and contrasts plant and animal cells both visually and descriptively. It is highly interactive.
3. The Encyclopedia Britannica Online - http://www.school.eb.com/all/comptons/article-9273572
This encyclopedia article is designed for middle school students and describes many aspects of the cell. You are able to click on the various parts of the cell using the menu on the left side of the page. This site may only be available to you at school.
4. The Cell Page – http://sun.menloschool.org/~cweaver/cells/index.html
This site shows great graphics of the plant and animal cells. Also, you can click on any organelle and get more detailed color images of the cell parts and descriptions of their functions.
Part 4: The Roundup
Share the information you have discovered by completing a “WANTED” poster for your organelle. You may use the “WANTED” posters provided or make your own! The poster should include:
1. A large “WANTED” displayed
2. A mug shot (printed picture) or a sketch from a sketch artist (hand drawn) of your organelle/structure
3. Descriptive answers (in your own words!) to all 3 questions in Part 2 – Function, Description of appearance, Location in Types of Cells and Location in Cell.
4. An educated guess to the following question: What is the relationship between structure (the way the organelle looks) and function (the job the organelle does)? Or, does the way the organelle look help it do it’s job?
Thursday: Organelle Trail
Friday: Test over Bacteria, Protist, Fungi
Posted by: Team 7.2 Science
| @ January 18, 2010 9:00:51 PM EST ( ) |
Monday: Turn in Bacteria Worksheet assigned on Wednesday
Notes over Symbiotic Relationships
Computer Lab: Study Island- Kingdoms and Review
Tuesday: LAB day, correct Bacteria worksheet, Fungus/Protist Review
Wednesday: Fungus/ Protist Worksheet, Symbiosis activity
Thursday: Review Game, Assessment tomorrow!!
Friday: Virus, Archaebacteria, Eubacteria, Fungus, Protist Assessment
Posted by: Team 7.2 Science
| @ January 11, 2010 5:46:03 PM EST ( ) |
Monday: Define the following
1. virus
2. host
3. parasite
4. bacteriophage
5. bacteria
6. flagellum
7. binary fission
8. asexual reproduction
9. sexual reproduction
10. conjugation
11. endospore
12. pasteurization
13. decomposer
Copy Virus notes from board. Use notes to complete virus worksheet. What is not completed in class is homework.
Virus Notes
Many people think viruses are one of the dangerous agents for the survival of humans. A virus is a microscopic particle that invades a cell and takes over the cell and has the cell make copies if the virus, which eventually destroys the cell and when the cell ruptures all of the copies of the virus are released to invade more cells. Viruses are not living, but the do contain protein and nucleic acids (they are not considered living because they cannot reproduce themselves without controlling a cell, they must use a different cell to do this, they cannot live on their own, they do not eat, grow or breathe.
The only way in which viruses are like organisms is that the can multiply.
Again, viruses invade a cell and instruct the cell to produce viruses instead of new healthy cells. The virus must have a host cell to invade and make new viruses. A host is an organism that supports a parasite. Viruses are not cells; they do not have cytoplasm or organelles.
Classifying Viruses
Viruses can be grouped into the type of disease they cause, their life cycle, or the type of genetic material they contain. Viruses can also be classified by their basic shape. Some are cylinders, some are crystals, some are spheres, and some look like spacecraft.
How Viruses Work
Viruses find a host cell and inject their nucleic acids and proteins into the cell. The virus then takes control of the cell and makes copies of it. As the host cell is destroyed and breaks open, new viruses are released to invade more host cells. Now the cycle can start again to produce even more viruses. This cycle is called the lytic cycle. When viruses first enter the host cell they allow the cell to copy itself and then the virus end up in two different cells and as this occurs, the virus is utilizing the host cell to make more. The cycle of allowing the host cell to copy itself is known as the lysogenic cycle.
Active vs Hidden viruses
Active viruses enter cells and immediately begin to multiply, leading to the quick death of the invaded cells. Hidden viruses "hide" for a while inside host cells before coming active.
Tuesday:
Answer questions over viruses and worksheet.
Bacteria notes, graphic organizer, foldable.
Students need to make sure they are updating their table of contents for their Kingdoms folder. All information given from last Friday on should be kept in their Kingdoms Folder. Students may bring it home to study or keep it in my room.
Bacteria are one of the smallest and are the simplest organism on the planet. They are also the most abundant. Many bacteria cause illnesses, but scientists have discovered that many bacteria are beneficial to humans and our way of life (from medicine production to food production). We will explore how bacteria are classified and some uses of bacteria as well as unique cell structure. Some of the material should be a review because we have already learned it in previous lessons.
Classifying Bacteria: All organisms on Earth fall into six kingdoms: Protista, Plantae, Fungi, Animalia, Eubacteria, and Archaebacteria. As you can easily tell, bacteria make up the kingdoms Eubacteria and Archaebacteria. These two kingdoms contain the oldest forms of life on earth.
RECALL: Bacteria are single celled organisms that do not have nuclei (nucleus). A cell with no nucleus is called a prokaryote. A prokaryote is capable of cellular respiration, move around, and reproduce. Since the prokaryotes have these features, they can function as an independent organism.
RECALL: Bacteria Reproduction
Most bacteria reproduce by a type of simple cell division known as binary fission. During binary fission the DNS is copied (replicated) and one copy ends up in each new cell. RECALL: Binary fission is NOT mitosis or meiosis, the DNA is replicated and then the cell gets longer and then divides in the middle with one copy of the DNA in each cell.
Bacteria when Conditions are Unfavorable
When the conditions become unfavorable for bacteria, some species will produce thick protective membranes and then they are called endospores. Many endospores can survive freezing, drying out, and even boiling. After the conditions become favorable for the bacteria, the endospores will break open and the bacteria become active again. Some endospores have been estimated to be millions of years old and when scientists improved the conditions the bacteria inside became active again. Ethical Question: Should we try to get bacteria from endospores to become active again after being enclosed for millions of years? Could the bacteria be of such dangerous proportion that we may not be able to stop a disease that it introduces? These are things we have to think about.
Shapes of Bacteria
There are three shapes of bacteria, 1). Bacilla, 2). Cocci, and 3) Spirilla. Bacilla shaped bacteria appear as short rods. Cocci bacteria are spherical shaped. The Spirilla are spiral shaped (like a cork screw).
Locomotion of some Bacteria
Some bacteria have flagella that serve as their source of locomotion (movement). The flagella are whip like structures that spin like a cork screw to move the bacteria through the liquid they are in.
Kingdom Eubacteria
Most bacteria are eubacteria. These bacteria are classified by the way they get their food. Some are consumers, others are decomposers and some are producers. The consumers get their nutrients from other organisms. The decomposers get their nutrients from dead organic matter. The producers are capable of making the nutrients they need through photosynthesis (using the sunlight to produce sugars). The producers, like plants contain chlorophyll that captures the energy from the sunlight.
Some bacteria producers are called cyanobacteria, and they live in many different types of water environments. Cyanobacteria have chlorophyll that enables them to carry out photosynthesis. Some scientists have thought that millions of years ago some of the cyanobacteria became adapted to living within cells that had nuclei and as millions of years passed; the adaptations resulted in the first plants being formed.
Kingdom Archaebacteria
Achaebacteria are believed to be ancient bacteria and they are able to survive in environments other organisms living today cannot survive. The environments we find archaebacteria living in are the hot springs and some species survive deep below the ice of Antarctica. Archaebacteria are genetically different from eubacteria. Some archaebacteria do not have cell walls and those that do, the cell walls are chemically different from other organisms.
There are three types of archaebacteria; 1). Heat lovers, 2). Salt lovers, and 3). Methane gas producers. Some heat lovers can survive in temperatures as hot as 360 degrees Celsius (almost 700 degrees F) . Salt lovers live in environments like the Dead Sea, where other forms of life are inexistent. The methane producers give off methane gas where things are decomposing (one place you may find them is in swamps).
SECTION 2 What Do Bacteria Do?
The majority of bacteria are microscopic, in other words we cannot see them without a microscope. Some bacteria are bad for us and some are very beneficial. We often only hear about the bacteria that cause illness and death, so we think all bacteria are bad.
Nitrogen Fixation: RECALL: A species of bacteria is capable of taking atmospheric nitrogen and converting it into a form of nitrogen that plants can use. All organisms must have nitrogen for making proteins and DNA. RECALL: Living organisms that are not producers must get their nitrogen from eating plants and other organisms. Nitrogen enters organisms as they feed on plants and other organisms and when the living organism dies and decomposes, the nitrogen is released back into the soil. Some plants may take this in or a different species of bacteria may consume it and convert it back into atmospheric nitrogen. This is the nitrogen cycle. RECALL: Everything is cycled or recycled through nature.
Some bacteria help humans clean up messes that we make. Bioremediation is the use of bacteria and other microorganisms to change pollutants into harmless chemicals. Bacteria are used to clean up certain types of agricultural, industrial and municipal wastes. We have also used species of bacteria to clean up oil spills.
People and Bacteria: The Benefits
Scientists have used bacteria to produce types of medicines, insecticides, cleaners, adhesives, foods and other products we use. Some bacteria have been used to make antibiotics, which are used to kill harmful bacteria and other harmful microorganisms. Scientists have used a species of bacteria to make insulin that diabetics can use. Diabetes is a disease in which a person’s pancreas does not produce enough or good quality insulin. Scientists have learned how to make insulin and the diabetics can inject the insulin into their body to control the level of blood sugar. A too high or low of a blood sugar level can lead to death of organisms.
Scientists have also learned that bacteria can be used to make yogurt, buttermilk, cheese, and sour cream. Scientists have learned how to use lactic acid bacteria to convert the milk sugar into lactic acid, which acts as a preservative and adds flavor to the food. Examples of other foods made by using bacteria in specific ways include: sour dough bread, cheeses, pickles, some sausages, and some vinegars.
HARMFUL BACTERIA
Bacteria that cause diseases are called pathogenic bacteria. Some diseases you may have heard of are dental cavities, ulcers, strept throat, food poisoning, bacterial pneumonia, lyme disease, tuberculosis, leprosy, typhoid fever, and bubonic plague.
Other organisms are also affected by pathogenic bacteria. Plants, animals, protists, fungi and even certain types of bacteria can be harmed by pathogenic bacteria. Some grains, fruits, and vegetables can be damaged by pathogenic bacteria.
Wednesday:
Protist Vocabulary:
1. protist
2. protozoan
3. pseudopod
4. contractile vacuole
5. cilia
6. symbiosis
7. mutualism
8. algae
9. spore
Protist notes, graphic organizer, foldable.
ome protists are so small they must be seen with a microscope, while others can easily be seen without magnification. Some are like plants, some are like animals, and some are like neither. All protists are eukaryotic. That means they all have a nucleus in each of their cells. Most protists are single-celled, but there are some that are multi-cellular.
Some protists have chlorophyll and are producers. (RECALL: photosynthesis). Other protists are consumers; they cannot obtain their energy from the sun and must get their food from the environment. Protists are classified by the way they obtain their energy. This process groups them into fungus-like protists, plant-like protists, or animal-like protists.
FUNGUS-LIKE PROTISTS
A fungus is an organism that obtains its food from dead organic matter or from the body of another organism. The protists that obtain their food in this way are fungus-like protists. Fungus-like protists are consumers that secrete digestive juices into the food source and then absorb the digested nutrients. These protists also reproduce like fungi. We will look at slime molds and water molds.
Slime Molds
Slime molds are thin masses of living matter. They look like colorful, shapeless blobs of slime. They live in cool, moist, shady places. You can find them in woods and in freshwater. Slime molds feed on bacteria, yeasts, and small bits of decaying plant and animal matter. They surround their food and digest it. As long as it has water and food, it will grow. When conditions become unfavorable for a slime mold to grow, they form stalk like structures that are rounded on the tops. These rounded knobs contain spores and the knob like structures are called sporangia. When conditions improve, the sporangia open and release the spores and new slime molds will grow from the spores.
Water Molds
These are also fungus-like protests. They are usually small, single-celled organisms. They survive in water, moist soil, and other organisms. Some are decomposers and eat dead organic material, but many are parasites (must have a host). Parasites invade the body of another organism to obtain the nutrients they need to survive. Some parasitic water molds cause diseases. An example of a water mold causing a disease is the “late blight” with the potato serves as the host. Other water molds use fruit as their host and this almost caused the collapse of the French wine industry in the 1800’s.
Plant-Like Protists
These protists are producers and like plants have chlorophyll in their cell(s) that captures sunlight to make the sugars they need for survival (they carry out photosynthesis). The plant-like protists are known as algae. Even though they have chlorophyll for photosynthesis, some algae have other pigments that cause them to have other colors than green. There are species that will look brown, red, and reddish brown. Some of the algae are multi-cellular and are several meters in length. If you have heard of kelp and know it grows several meters in length, it is one example of algae (protist).
The single celled algae cannot be seen without a microscope (very small). They also contain chlorophyll and live near the surface of the water to capture sunlight for photosynthesis. We call these phytoplankton, and they make up the base of most aquatic food chains. They also produce most of the world’s oxygen.
Red Algae: Most of the seaweeds are red algae. They contain chlorophyll and a red pigment that gives them their red coloration. The red algae live mainly in the warm tropical seawaters of the tropics. The red pigment gives them a special property. It allows the red algae to capture light down to 260 meters below the surface. The red wavelength of light penetrates the deepest into water, so it is the last wavelength of light filtered out naturally by the water.
Brown Algae: Most of the seaweeds found in cool climates are brown algae. They attach to rocks or other algae and form large floating beds. Brown algae have chlorophyll and a yellow brown pigment. Many brown algae are very large and rapid growers (some grow up to 60 meters in one growing season). The tops of the brown algae are exposed to sunlight and the sugars made here are transported to the lower parts of the algae where light does not reach.
Green Algae: The green algae are the most diverse group of plant-like protists. They are green because of chlorophyll. The chlorophyll is the main pigment so the color is green. Most live in water or moist soil, but you can find some in melting snow, on tree trunks, and even inside other organisms. Many green algae are single celled, microscopic organisms, others are multi-cellular. The green algae have a few members that may grow up to 8 meters in length. Some of the green algae that are single celled are found living in colonies. One example of colonial algae is Volvox.
Diatoms: Diatoms are single celled organisms. They are found in both saltwater and freshwater environments. They also get their energy from photosynthesis and they make up a large percentage of phytoplankton. The diatoms are composed of cell walls made of cellulose and silica (glass like substance). The diatoms that die will settle to the floor of the body of water they are in. They are then gathered for use as abrasives in silver polish, toothpastes, filters, and insulation.
Dinoflagellates: Most dinoflagellates are single-celled algae. They are primarily in saltwater. With a few found in freshwater and snow. Dinoflagellates have two whip-like strands called flagella, which serve as a locomotion device. The flagella cause the dinoflagellates to spin through the water. Most of the dinoflagellates get their energy from the sun, but some are consumers, decomposers, or parasites. Some of the dinoflagellates are red and if the population gets very large, the water they live within will actually look red. This is known as a red tide and red tides are poisonous to shellfish. If an organism like the shrimp eats the dinoflagellates of a red tide they become toxic as the poison builds in their body. If humans and other organisms consume the poisoned shellfish, they may get sick.
Euglenoids: Euglenoids are single-celled protists that live primarily in freshwater. Most euglenoids have characteristics of both plant and animals. Like plants, they use photosynthesis, but when light is too low for photosynthesis, they become consumers like animals. Euglenoids can also move like animals. They have flagella that propel the organisms through the water. Some euglenoids do not have chloroplasts for photosynthesis. These species either consumes other small protists of absorb nutrients that are dissolved in their environment.
ANIMAL-LIKE PROTISTS: PROTOZOA
The animal-like protists are single celled consumers. These protists are also known as protozoa. /some protozoa are parasites. Many can move. Scientists are not real sure on how to group or classify protozoa, but many agree on four phyla. The four phyla are: 1). Amoeba-like protists, 2). flagellates, 3). ciliates, and 4).spore forming protists.
AMOEBA-LIKE PROTISTS
An amoeba is a jelly or slime like organism. They are found in freshwater, saltwater, in soil, or as parasites in animals. Amoebas have a structure called a contractile vacuole that pumps out excess water. Amoebas move with the aid of pseudopodia (false feet). The amoeba will extend a projection (pseudopod) and then the remainder of the Amoeba will “flow” into the area the pseudopod is located.
Amoebas feed like slime molds do; they surround their food source by engulfing it. This process forms a food vacuole. Enzymes move into the vacuole and digest the food item and the digested food moves into the cytoplasm of the amoeba. In order to rid it from the wastes, the amoeba simply reverses the process. A vacuole filled with waste is moved to the outer edge of the amoeba and then released from the amoeba.
Some amoebas are parasitic. Some species live in the human intestine and cause amebic dysentery, which is painful and often has bleeding ulcers involved along with frequent vomiting.
PROTOZOA WITH SHELLS
Some protozoa have shells and are called radiolarians. The shells are made of silica and look very glassy looking. Another example of protozoa with a shell is foraminiferans. Foraminifera have snail like shells made of calcium carbonate.
FLAGELLATES
These are protozoa that use flagella to move. The flagella wave back and forth to propel the organism forward. Some flagellates live in water. Others are parasites that cause disease. The flagellate Giardia lambia lives in the digestive tract of humans and other vertebrates. These also survive in streams. If hikers or any other outdoor enthusiast drinks from one of these streams and takes in one of the protozoa, he/she can get diarrhea and severe stomach cramps, but it usually does not kill the individual.
Some flagellates live in symbiosis. In symbiosis, one organism lives closely with another organism, and each organism helps the other survive. One example is a flagellate that lives in the gut of termites and they digest the cellulose the termites consume. Without the protozoa, the termite could not completely digest the cellulose.
CILIATES
Ciliates are the most complex protozoa. Ciliates have hundreds of tiny hair-like structures known as cilia. The cilia serve as a locomotion device; they propel the ciliate forward when they beat back and forth. Some ciliates use the cilia to push food in the water toward them. The most widely known ciliate is the paramecium. Ciliates have two kinds of nuclei, macro-nuclei, and micro-nuclei. The macronucleus controls the functions of the cell and the micro-nucleus passes genetic material to another individual during sexual reproduction.
SPORE FORMING PROTISTS
These are all parasites that absorb nutrients from their hosts. They have no cilia or flagella and they cannot move on their own. Spore forming protozoa have life cycles that involve two or more different hosts.
Plasmodium vivax is a spore-forming protist that causes malaria. Malaria is a disease that is carried by mosquitoes in tropical areas. Malaria can be treated with drugs, but even today there are over 2 million people that die form the disease each year. If a mosquito has the Plasmodium vivax and bites a human and transfers some of the protist to the human, it will infect the human’s liver and multiply inside red blood cells. The red blood cells will burst and release more of the protist and if the human gets bitten by another mosquito, the protist can be transferred to another human host.
REPRODUCTION of PROTISTS
Some protists reproduce asexually. RECALL: Asexual reproduction involves only one parent. They reproduce by dividing in half in a process called fission.
Some protists reproduce sexually. Sexual reproduction requires two parents. Example: the paramecia often reproduce sexually by a process called conjugation. During conjugation, two Paramecia join together and exchange genetic material using their micro-nuclei. Then they divide to form four organisms with new combinations of genetic material.
Some protists reproduce sexually and asexually. In some algae, asexual and sexual reproduction alternate between generations.
Thursday:
Fungi vocabulary:
1. fungi
2. hyphae
3. fruiting body
4. budding
5. lichen
Fungi notes, foldable
You are probably more aware of fungi than you were of protists. Some examples of fungi are mushrooms, bread mold, yeast, and athlete’s foot is caused by a fungus. Fungi are used to make certain cheeses, antibiotics, and soy sauce. So fungi can and are beneficial if they are of the correct species, if they are not, they may cause death in a worse case scenario.
Characteristics of Fungi
Fungi are eukaryotic consumers. They are so different from other organisms though, that scientists place them in a classification kingdom of their own. Fungi come in many shapes and colors, but they all have similar ways of obtaining food and reproducing.
How Do Fungi Get Their Food?
Fungi are consumers, but they do not eat their food or engulf it. Fungi must live near or on their food supply. They get their nutrients by secreting digestive juices onto the food source and as the food source decomposes, the fungi absorb the nutrients that have dissolved. Many fungi are decomposers and they feed on dead plant and animal matter. Some other fungi are parasites, and some are involved in symbiotic relationships with other organisms.
Some fungi grow on the roots of plants and release acid that changes minerals in the soil into forms the plants can use. The fungi also protect the plant from disease causing organisms.
Fungi are eukaryotic and have a nucleus. Some are single-celled, others are multi-cellular. Multi-cellular fungi are made up of chains of cells called hyphae. The hyphae are unique in that they have pores in the cell wall that allows cytoplasm to transfer from one cell to another. The hyphae grow in a mass that is called a mycelium. The mycelium is the major part of the fungus. The mycelium is under the surface of the soil and out of sight.
How Do Fungi Reproduce?
Reproduction of fungi can be sexual or asexual. If a hyphae breaks away from the mycelium, it can begin growing a new fungus. This is an asexual reproductive process (one parent). Another asexual reproductive process involves the production of spores. Spores are small reproductive cells protected by a thick cell wall. Spores are light and are easily dispersed by the wind. If the spore lands in a area where the growing condition is good, it will produce a new fungus.
Sexual reproduction of fungi involves forming special structures to make sex cells. The sex cells join together to produce sexual spores that grow into a new fungus.
Fungi Groups
Fungi are grouped into four forms 1). Thread-like, 2). Sac fungi, 3). Club fungi, and 4). Imperfect fungi. These are based on the shape and the way it reproduces.
Thread-like fungi: Molds are an example here, especially bread mold. Molds are shapeless fuzzy looking fungi. The thread-like fungi can reproduce asexually. Extensions of the hyphae grow into the air and have round ball looking structures on the tips. These round structures are called sporangia. When the sporangia burst open, many thousands of spores are dispersed into the air.
Thread-like fungi also reproduce sexually. Two hyphae from different individuals can join and form specialized sporangia. These sporangia can survive unfavorable conditions like heat, cold, and drought. Once the conditions improve to “growing conditions” the sporangia release the spores and new fungi grow.
Sac Fungi: This is the largest group of fungi. The sac fungi include yeasts, powdery mildews, truffles, and morels. Sexual reproduction in this group involves the formation of a sac called the ascus. These sacs give the sac fungi their name. Sexually produced spores develop in the ascus. They also reproduce asexually. Example: Yeasts produce asexually by budding. Budding involves a new cell pinching off from an existing cell. Some sac fungi are very useful to humans. Yeasts are added to flour to cause it to rise when baking breads. The yeast breaks down the sugars and gives off the carbon dioxide that causes the bread to rise.
Some sac fungi are used to make antibiotics and vitamins. Truffles and morels are sac fungi and are prized for their flavors they can add to foods.
Some sac fungi are parasites that cause damage to plants. One example id the Dutch Elm Disease that kills elm trees and the Chestnut Blight that killed the American Chestnut trees.
Club Fungi: The shape you think of as a mushroom or toadstool is characteristic of club fungi. During sexual reproduction the hyphae produce special club like structures called basidia and the sex spores develop inside the basidia.
When we see a “mushroom” we are only seeing a small portion of the fungus. The majority is under the surface of the ground and the structure “mushroom” we see is located at the ends of the hyphae. That is why it appears mushrooms often grow in halo shapes or circles.
The most well known mushrooms are the gill mushrooms. If you look under the “cap” of the mushroom you will see slits or gills that house the spores. Only touch mushrooms if you can positively identify them as a safe to handle species. Many are poisonous to the point that ingesting them can cause death.
The club fungi also include shelf fungi, which are often seen growing on the sides of trees and resemble half-moon shaped shelves. You may have stepped on a puffball and seen the spores float away in the air. The puffball is an example of club fungi. There are also club fungi that are called smuts, or rusts, which often infect crops and ruin or decrease their yield.
Imperfect Fungi: this group has all the other fungi that do not fit into the other fungi groups. The imperfect fungi do not reproduce sexually. Most of the members of this group are parasites that cause diseases in plants and animals. One common disease many humans get is athlete’s foot. Another fungus in this group produces a poison called aflatoxin, which can cause cancer.
Do not make the mistake of thinking all imperfect fungi are disease causing. The fungus Penicillium is the source for the antibiotic penicillin, which has been used for years against bacterial infections. Also, some imperfect fungi are used to make cheeses, soy sauce, and the citric acid in cola drinks.
LICHENS
A lichen is a combination of an fungus and a algae that grow intertwined in a symbiotic relationship. The lichen is different from either of the two that are in the symbiotic relationship if they were growing alone.
Lichens are producers, and get their food by carrying out photosynthesis. The lichen can withstand drying out because the walls of the fungus protect the algae from drying.
Lichens need water, air and light to grow. This is why they are most often the pioneer species in primary succession. As the lichens grow and die, they fill the cracks on the rock(s) with organic material that allows other organisms to begin growing. Lichens absorb water and minerals from the air and they can serve as a “pollution detector” because if lichens are not present in an environment they would normally be found, there may be a high level of air pollution.
Notes adapted from Robert Littlejohn
Friday:
Student half-day dismissal at Noon
Student/Faculty Basketball game
Have a wonderful Holiday!!
Posted by: Team 7.2 Science
| @ December 14, 2009 10:58:48 AM EST ( ) |
Monday: Lab Day- Alien Classification, Study Guide for Genetics and Evolution
Tuesday: Review
Wednesday: Review
Thursday: Benchmark 2 over Genetics and Evolution
Friday: 6 Kingdoms Introduction
As scientists began classifying organisms, they have arranged all living things into six kingdoms. The kingdoms are 1) Archaebacteria, 2) Eubacteria, 3) Protista, 4) Plantae, 5) Fungi, and 6) Animalia. We will look at each of these in this chapter and in later chapters we will look more closely at the phyla in the kingdoms, as well as some looking at some organisms at the species level.
Kingdom: Archaebacteria
Scientists believe this group of bacteria has been on Earth for 3 billion years. The prefix Archae comes from the Greek word meaning “ancient”. Archae bacteria live in places that most organisms cannot currently survive. One example is very hot springs coming out of the Earth like you would find in Yellowstone National Park.
Kingdom: Eubacteria
These bacteria are found in soil, water, and other living things and include most of the species of bacteria living presently. An example of a Eubacteria is Escherichia coli which can be found in the human intestines. It get the nutrients from the decomposing foods we eat and produces vitamin K that our body takes up to use. Other bacteria are used to make yogurts and cheeses. Most people only think about bacteria causing sinus infections or other illnesses, but as you have just read, there are some species humans use to benefit ourselves. Bacteria also decompose dead organisms. If this did not happen, we would have dead carcasses laying everywhere.
Kingdom: Protista
Members of this kingdom are commonly called Protists. These are single celled or simple multi-cellular organisms. The protests are eukaryotes (RECALL), which means they have membrane bound organelles. Protists are not plants or animals or fungi. Scientists think that protists evolved from ancient bacteria. Scientists also believe that much later, the protests gave rise to plants, fungi, animals, and modern protests.
Protists include protozoa, which are animal like protests; algae, which are plant like protests; and slime molds and water molds, which are fungus like protests. Most protests are single celled, but there is some multi-cellular like giant kelp.
Kingdom: Plantae
Plants are complex multi-cellular organisms that are usually green and use the sun’s energy to make sugar by a process called photosynthesis. RECALL: Photosynthesis, revisit the formula we learned during the photosynthesis chapter.
Plants are in various sizes and colors. The Giant Sequoia trees are the largest and a small plant called duckweed is about the size of an eraser tip on a pencil.
Kingdom: Fungi
Examples of fungi you may have seen before includes mushrooms and bread mold. Fungi (singular is fungus) were originally classified as plants, but fungi do not get their nutrients through photosynthesis. Fungi do not have any animal characteristics. Fungi absorb nutrients from their surroundings after breaking the organic material around them down with digestive juices.
Kingdom: Animalia
Animals are complex multi-cellular organisms that belong to the kingdom Animalia. Most animals can move from one place to another on their own and have a nervous system that helps them sense and react to their surroundings, If we looked at animal cells under a microscope, we would notice that they are different from plant cells, fungi cells and are also different from most protest cells, and bacteria cells because animals do not have a cell wall.
Posted by: Team 7.2 Science
| @ December 6, 2009 12:20:27 AM EST ( ) |
Monday: CRCT Coach Book , Evolution Review, Classification Notes
Homework: Prepare a way to remember the 8 levels of classification in order:
Domain, Kingdom, Phylum, Class, Order, Family, Genus, Species
Tuesday: Classification Activities, Dichotomous Key Examples
Wednesday: Review Game
Homework: Create ten test questions with answers about Evolution. True/False and Yes/No answers are not allowed.
Thursday: Evolution Post Test, Classification Vocabulary:
1. classification
2. taxonomy
3. binomial nomenclature
4. genus
5. species
6. prokaryote
7. nucleus
8. eukaryote
9. phylogeny
10. kingdom
11. dichotomous key
Friday: Guidance Counselors will be in the room for the duration of the class period.
Posted by: Team 7.2 Science
| @ November 30, 2009 7:28:43 AM EST ( ) |
Monday:
Read Chapter 6, section 3. Answer the section review questions
Squirrel Island: Major project. Began working on Friday. Due tomorrow.
Blending butterfly data
Tuesday:
Finish and present Squirrel Island Project. Early dismissal today.
Squirrel Island:
Purpose: To explain how adaptations help organisms survive in different environment
Background Information: Mutations are random changes in the genetic information of an organism. They cause new traits in an organism. Most are harmful, but a few are neutral or even beneficial. There are two main types of genetic mutations: a point mutation and a frame shift mutation. In a point mutation, one of the bases (chemicals) in the chain of DNA is replaced by a different base. In a frame shift mutation, one base pair is "deleted,"
so it throws off the DNA sequence, leading to different proteins that are usually useless or harmful. A beneficial or neutral mutation can quickly become harmful when the
environments change. The environment greatly affects an organism’s ability to survive, and even a small change can be harmful to some organisms.
Some examples:
• The panda’s "thumb" is actually an enlarged bone of the wrist. In the panda’s environment, bamboo is the main food source. It is difficult to handle and break the hard stalks, so an enlarged wrist bone helps to grasp the bamboo. In another environment where the food source is not plants, an extra ‘finger’ would have little benefit, perhaps even be cumbersome. The mutated hands of pandas have been beneficial only because of their need for a better grip on bamboo.
• The kokapo is a strange flightless parrot that lives in the brush on the mountains of New Zealand. Before man reached its shores, the island was almost mammal-free, with no ground predators of birds. As a result, the many ground dwelling birds lost the ability to fly, because there was no need. Their wings are small and useless. When man did come they brought mammals, such as cats and weasels. The kokapo
was easy prey for them, and is now nearly extinct. This happened to several other birds, including the kiwi. These birds inability to fly quickly caught up to them when the environment changed, showing how their mutation of bad wings was harmful in different environment.
• The penguin has a similar situation, living in the waters of Antarctica and surrounding places. They have evolved into flightless birds that are cumbersome and ineffective on land, but are masters of the water. In Antarctica, the sea is the best place to get food, so that is where the penguin has hunted. It has gradually lost its ability to fly, attained huge amounts of insulating blubber, and gained mutated legs that are great for swimming and terrible for walking. If the penguin was not in the environment it is so well suited for, it would be very vulnerable and
helpless. The mutations that have helped it survive in Antarctica would quickly become useless in a place like the grasslands or mountains. In an environment without water nearby, mutated wings and legs suited for swimming are useless.
Materials: Drawing Paper and Colored Pencils
Procedure:
1. Put your name on the back of the drawing paper.
2. Use a PENCIL
3. You will be assigned an island habitat.
4. Design a squirrel that has adapted to the environment of the island (beneficial mutations).
5. Draw the island environment and the squirrel.
6. On the back of your drawing, describe the adaptations, and why they are beneficial to the squirrel.
7. Neatness and attention to detail matters!
Posted by: Team 7.2 Science
| @ November 23, 2009 7:47:35 AM EST ( ) |
Monday:Evolution Notes
Tuesday - E.Q.: What is speciation? Introduce Chapter 6. Homework: Study Evolution Notes!
Wednesday - E.Q.: What is generation time? Introduce Darwin. Homework: Get Chapter 6 vocabulary completed and look over the information from today we covered in class.
Thursday - E.Q.: What is a fossil? Readings chapter 6, section 3. Complete the worksheet questions that correspond to today's readings. Homework: Study Chapter 6 material we have covered so far for a quiz tomorrow.
Friday - E.Q.: What is absolute and relative dating? Quizzical questions from Review material. Readings Chapter 6,section 3. complete the worksheet from the notes that corresponds to today's readings. Homework: Study the materials from Chapter 6 we have read and covered.
Posted by: Team 7.2 Science
| @ November 8, 2009 9:02:09 PM EST ( ) |
Monday: Pedigree Notes with worksheet
Tuesday: Lab Day
Wednesday: Vocabulary Quiz!! Sexual vs. Asexual Reproduction Notes
Thursday: Genetics and Heredity Review Game
Friday: Test over Genetics and Heredity
Posted by: Team 7.2 Science
| @ November 2, 2009 5:39:40 AM EST ( ) |
Chapter 6 Genes and Gene Technology
Section 1
We now know that genes can be passed on from one generation to another. Genes are located on chromosomes. Chromosomes are made of protein and DNA
eoxyribonucleic acid).
What must Genes be able to do?
Genes must be able to do two things: 1) supply instructions for cell processes and for building cell structures, and 2) must be able to be copied each time a cell divides, so that each cell contains an identical set of genes.
What are Nucleotides?
Nucleotides are the subunits that make up DNA. There are four subunits that make up these nucleotides. Each nucleotide consists of three different types of material; a sugar, a phosphate, and a base. All nucleotides are identical except for their base. The four bases are: adenine, thymine, guanine, and cytosine. Each of these has a slightly different shape. The bases are usually referred to by the first letter in their name. Example: Cytosine = C, Guanine = G, Thymine = T and Adenine = A.
Chargaff’s Rule
Erwin Chargaff discovered that the amount of adenine is always equal to thymine and the amount of guanine is always equal to that of cytosine. When Chargaff released his finding, no one knew what to think about them, but as we later learned he was correct.
Rosalind Franklin (Women in Science)
Rosalind Franklin was studying DNA molecules and used X-rays to get an “image” of what DNA looked like. She reported that DNA looked like a coil or spiral shaped (like a twisted ladder).
Watson and Crick
James Watson and Fredrick Crick were two scientists also studying DNA molecules and trying to determine what DNA also looked like. James Watson did not give much attention to Rosalind Franklin’s idea about the shape of a DNA molecule, but Fredrick Crick respected her work and continued to look into Rosalind Franklin’s findings. Guess What!? Rosalind Franklin was correct. As Watson and Crick soon found out, DNA did look like a twisted ladder. Watson and Crick called their model a double helix.
What is the Structure of DNA?
Picture in your mind a ladder. The “handrails” contain the sugar and phosphate components of the nucleotide and the “rungs” (places where you would position your feet to climb a ladder) is where the bases are located. Remember that the bases are of a specific shape and adenine and thymine always pair up and cytosine and guanine always pair up. So if we have GGATC on one side of the ladder composing half the rung, the other side must contain CCTAG to compliment or match up to the bases on the other side of the ladder.
Why is Making Copies of DNA Important?
It is important to make copies of DNA because DNA is used to make proteins. We call this coping process replication. DNA replicates by splitting down the middle (imagine cutting a ladder in half at the rungs, or a zipper being unzipped down the middle). As the DNA strand is “unzipped”, one half of the strand must be used for copying or act as a template or pattern for a new complimentary side. Try your skill: What is the complimentary copy for the bases GCGGTCCAAAT? If you chose CGCCAGGTTTA, then you are correct.
What order can the bases occur? The bases can occur in any sequence depending on the protein that needs to be produced. The order of the bases supplies the information on how to make each protein and/or trait the cell needs.
DNA has the same bases in all organisms, the difference is how the bases are arranged in their order. So, all organisms have DNA that consists of the same bases (from bacteria to dogs, snakes, alligators, fish or what ever organism you want to name). Remember though that the order makes all organisms different from each other. All organisms are similar in that they have DNA, but all are different in the order the bases occur or the sequence the bases are arranged.
Recall: Gregor Mendel conducted research that identified how genes are passed from parents to offspring or one generation to the next. We only discussed the possibility of having dominant or recessive traits, but there are always a few exceptions to the rule.
Incomplete Dominance
During Mendel’s research, he did not find any traits that “blended” together, but there are occasions where two or more genes affect the trait being looked at. In other words, one trait is not dominant over another, but they both have influences. This is known as incomplete dominance.
Example: There is a flower called the snapdragon. In the Red flower form, the alleles are R1R1. In another form the flower is white and the alleles are represented as R2R2. Try crossing R1R1 X R2R2. If you did your Punnett Square correctly, you should know that all four of the possibilities for the cross are R1R2. When you have these alleles in the snapdragon, the result is a pink flower (both the white alleles and the red alleles have an affect and the result is pink). This is a good example of incomplete dominance
Weird Gene Expression
Sometimes some genes may affect more than one trait. Our book discussed a white tiger. The gene that influences the white fur color also influences eye color and white tigers have blue eyes.
In humans, eye color is often affected by more that one gene. Different shades of blue or green eyes are two examples. With this example, the different colors are due to different amounts of pigment present.
Can the Environment have an Influence on your Traits?
Oddly enough, the environment can have an effect. Let’s find out how. Suppose you have the traits to be tall. If you do not get the proper nutrition or nutrients, you may not reach your full height potential that your genes are programmed for. Another example, you may have inherited specific genes for a talent, but if you do not practice your talent will not develop to the potential you have inherited.
Review Section One
1. What are the subunits that make up DNA?
2. What are the components that make up nucleotides?
3. What shape did Rosalind Franklin say the DNA molecule was in?
4. What did James Watson and Fredrick Crick confirm? (shape)
5. What makes all organisms have something in common?
6. I have extracted the DNA from a cell and determined there was 43 percent guanine in the DNA. What percent of cytosine must be present?
Answers to Review Section One
1. The subunits of DNA are nucleotides.
2. The compounds that make up nucleotides are phosphate, a sugar and the base (cytosine, guanine, adenine, thymine).
3. Rosalind Franklin determined the shape was a coiled or a spiral shape.
4. Watson and Crick confirmed that the shape of the DNA molecule was a double helix (looks like a twisted ladder).
5. All organisms have DNA and this makes them have something in common, but the bases are not in the same sequence and this causes them to be different.
6. There has to be 43 percent of cytosine because the amount of cytosine must equal the amount of guanine and the amount of adenine must equal the amount of thymine.
Practice, More from reading!
1. Why did scientists think that proteins instead of DNA carried genetic information? Answer: Because proteins are much more complex than DNA.
2. What is incomplete dominance? Answer: In incomplete dominance, each of the two alleles that determine a trait has it’s own degree of influence.
3. True/False: Tigers with white fur are probably going to have blue eyes. If you said true, you are correct!
4. If a person inherits a gene to be tall, that person will be tall no matter what. Is this statement true or false?
5. If we found the bases AATACGTTC, what would be the complementary base chain? If you said TTATGCAAG you are correct.
6. We can relate to the shape of DNA if we can picture a twisted ladder (True or False). True, it is also called a double helix.
7. Food for thought: If we took the entire DNA in your body and stretched it out, it would stretch from the Earth to the Sun and back two times…. Wow, that is some length!!
Funny Time: Why did the mutant chromosome go to the tailor?
Because it had a hole in its genes!
Section 2
How does DNA Work?
Scientists knew that the DNA held some sort of code that told the cell what to do, but they wanted to “break the code” in order to understand the instructions better.
Genes and Proteins
Scientists discovered that the sequences of the bases in the DNA strand read like a book. Each set of three bases made up the “word” that coded for a specific amino acid. RECALL: Amino acids are the building blocks of proteins. So DNA tells our cells what proteins to make. Let’s find out how.
The order of the bases determines the order of the amino acids in a protein. Each gene is a set of instructions for making a protein. Why are proteins so important? Because proteins are found throughout the cell and serve as chemical messengers. They also help determine how tall you will grow, what color your eyes are, if you are colored-blind or not, if your hair is curly or straight. These are a few examples of the importance of proteins.
The three bases that code for a particular protein is called a codon. A messenger carries the DNA half of strand with the codons out into the cytoplasm from the nucleus and into a ribosome. At the ribosome site the ribosome attaches the amino acids into the proper sequence to form the appropriate protein. Essentially, the ribosome is the “factory” where the proteins are made.
Changes in Genes
Genes are specific in the proteins they produce and the codons must occur in the proper order or a problem may result. Sometimes extra bases can be added, subtracted, or substituted and problems may occur. These problems are called mutations.
Mutation Types
If a base is left out, the mutation is called a deletion mutation. If a base is added (where we now have an extra base) it is called an insertion mutation. If there is a base substituted for another base we call it a substitution mutation.
Example:
Normal Base Pair Sequence: AACCTTGGA
TTGGAACCT
Base has been removed: ACCTTGGAA
TGGAACCTT
Base is added: AAACCTTGGA
TTTGGAACCT
Base is substituted: AACATTGGA
TTGTAACCT
If any of the changes occur, a mutation results. The mutation may not have any affect on the organism, or it could cause harm to the organism to the point that death results. Mutations do happen, but we are very fortunate that many of these mistakes are repaired in the cell, but sometimes the mistakes may not be repairable or they are not 100% repaired. A third situation that can occur if a mutation happens in sex cells is the mutation can be passed on to the next generation.
What can damage DNA?
Anything that can damage DNA is called a mutagen (capable of causing a mutation). Some examples that you may have heard of before are high energy radiation, ultraviolet radiation, chemicals (asbestos and benzene are two), and cigarette smoke to name some common mutagens. Can you think of others?
Specific example of a substitution Mutation
The bases GAA are the code for an amino acid called glutamic acid. If GTA occurs, it codes for an amino acid called valine. When valine is substituted in the wrong place for glutamic acid it can cause a blood disease known as sickle cell anemia. This effects the red blood cells. Normally the red blood cells are round and have a concave side on each side. When an individual has sickle cell anemia, the red blood cell is the shape of a crescent moon (or a sickle used to harvest grain). This causes trouble for the red blood cell to pass through the blood vessels. The sickle shape can cause the vessels to become blocked and is very painful.
What is a Pedigree?
A pedigree is a tool that can be used to map out a family’s genetic traits and determine the probability of the trait being passed on through generations. If a dangerous mutation has occurred in a family, the scientists and doctors may want to see if the mutation has occurred before and determine the probability of it occurring again if the couple wants to have more offspring.
Selecting Genes for Specific Reasons
Some genes may be selected for during crossing some plants or breeding some organisms. Scientists may want a type of agricultural grain to be resistant to certain fungi and if they can cross specific resistant grains, they can create a variety that will withstand becoming infected with the fungus.
Creating Specific Traits by Inserting Genes on Purpose
Scientists have also learned how to insert specific traits into a DNA strand. This can be controversial. Do we want to allow scientists to create organisms with specific traits that normally would not occur in nature? An example we read about in the book included scientists inserting a tobacco plant with some DNA from a lightening bug (firefly) and the result is a tobacco plant that grows.
This is known as genetic engineering. Do you think genetic engineering is okay to carry out? Why or why not?
What is we can identify a gene that will cure certain diseases if we allow scientists insert the gene into a strand of human DNA. Is this morally correct? Is it humanities duty to carry this type of research out?
Review Section 2
1. List and explain all three types of mutations.
2. What type of mutation did we discuss that causes a disease in the blood of humans, what is the disease called?
3. How is genetic engineering different from selective breeding?
4. What is the function of ribosomes (this should be a review)?
5. What are some examples from the environment that can cause mutations?
Answers:
1. Insertion – an extra base is added, Deletion – a base is deleted, Substitution – a base is substituted for another base.
2. Substitution mutation is responsible for sickle cell anemia.
3. Selective breeding involves selecting specific traits and breeding organisms that have those traits. Genetic engineering involves changing the DNA in the DNA strand of an organism.
4. Ribosomes are the “factories” to make proteins.
5. Ultra-violet radiation can cause skin cancer and this is because the cells DNA become mutated and the cell begins to divide faster than it normally would. Cigarette smoke is another example. The chemicals, asbestos and benzene can cause certain types of cancers due to the mutations they cause.
Study/Review Sheet for Chapter 6 Section 1
1. Chromosomes are made up of proteins and __________.
A. DNA C. Ribosomes
B. Nucleus E. Lipids
2. DNA is made up of units called ________________.
A. Genetic Tablets C. Nucleotides
B. Identical Partners D. Double Nitrogens
3. Adenine, Thymine, Cytosine, and Guanine are found on ________________.
A. The surface of our cells.
B. The nucleus cells in the nervous system
C. The nucleotides that make up our genes.
D. There are not such things as adenine, thymine, cytosine, and guanine.
4. Each nucleotide consists of three different types of material. What are they?
_________________, ________________, and _________________.
5. There are four possible bases in a nucleotide, what are the names of each of the bases?
____________________, _________________, __________________ and _______________________________.
6. The bases found in nucleotides are always paired up. Adenine is always paired with _____________________ in DNA and Cytosine is always paired up with _____________________________.
7. Our textbook gives an artists rendition of the shapes the nucleotides may occur. Draw the examples given from page 128. Do you notice how these could fit together?
8. ____________________ _____________________ is the lady who used X-rays to create images of DNA molecules.
9. James ________________ and Francis _______________ modeled DNA and determined the shape must be a _________________ _________________.
10. Describe and draw a double helix DNA molecule.
11. Draw the DNA molecule with at least 10 base pairs correctly matched (your drawing on this portion can be as if the DNA molecule appeared exactly like a ladder).
11. Make sure you understand that one side of the DNA molecule is complimentary to the other side regarding the bases that pair up.
12. When a DNA molecule makes a copy of itself it “unzips” resembling a zipper or an upside down Y. When DNA makes a copy of itself we say it ________________ or has undergone replication.
13. The DNA molecule splits down the middle where the _______________ meet when it replicates. One side is used as a template or pattern to form a new complimentary side.
14. When DNA replicates itself and no mutations have occurred, the two new DNA molecules are _________________ to each other.
15. Remember: DNA functions in the same way for all organisms. The same bases are found in all organisms, but it is the __________________ in which the bases occur that makes all organisms different from each other.
16. Sometimes one allele may not be completely dominant over another allele and the result is that both alleles play a role in the phenotype (recall phenotype: what the organism looks like or the appearance of an organism). When two or more alleles have their own degree of influence, we say the alleles exhibit ____________________ dominance.
17. What are two examples given to demonstrate incomplete dominance in organisms that we read and discussed? Explain this concept in terms of the white tiger and snapdragon flower.
18. We have discussed how alleles/genes can influence your development. Explain how our environment can influence our development.
Chapter 6 Section 2 Review/Study Questions
1. The bases adenine, thymine, cytosine, and guanine make up the _________________ of the code in DNA.
2. Each __________ bases code for a specific amino acid.
3. __________________ are made up of amino acids linked together (we have had this before).
4. The ____________ of the bases determines the order of the amino acids in a protein.
5. Scientists thought or DNA was found in proteins at one time because proteins are so ________________.
6. The first step in making a protein is copying the _______ strand that contains the code for the gene (protein) wanting to be made.
7. The “factory” where proteins are assembled is the _______________ (this is a review from cell organelles).
8. Sometimes there are mistakes that occur during the gene making process. These mistakes are known as ________________________.
9. The cause for a mutation is a change in the sequence of _________________ in the DNA.
10. If a base has been mistakenly left out, this type of mutation is known as a _______________.
11. If an extra base has been included into the code, this mutation is called a ________________ mutation.
12. If a base has been replaced by a different base in the code, this type of mutation is known as a _________________.
13. There are three possible outcomes to a mutation. One is it has no effect at all on the organism. The second possible outcome could result in a harmful change, and the last possibility is the mutation occurs in the sex cells and is passed from one ____________________ to the next generation.
14. DNA can be damaged by several means. Anything that can damage DNA is known as a _______________.
15. High-energy radiation, X-rays, and ultraviolet radiation can all cause ______________ and are classified as _____________________.
16. Notes to know: Many chemicals are mutagens and have been placed on lists giving specific warning to avoid direct contact with these chemicals. It is very important to read the manufacturers labels on chemicals because you will find the important directions and warnings located here.
17. A specific example of a substitution mutation is when valine is substituted for glutamic acid. The resulting substitution results in a red blood cell problem called _________________ cell anemia. Draw what a sickle cell would look like and explain some of the problems associated with sickle cell anemia.
18. A tool used for tracing a trait through generations of a family is called a _________________.
19. Most disorders resulting from mutations are recessive, therefore they only show up when both alleles for the trait are _________________.
20. The process that scientist use to transfer genes from one organism to another is called __________________ engineering.
21. When scientists breed (mate) organisms for desirable characteristics or to create a new breed, they often use ________________ breeding.
Adapted from Robert Littlejohn
Posted by: Team 7.2 Science
| @ October 27, 2009 11:32:18 AM EST ( ) |
Monday: Meiosis drawings, review worksheet
Homework: Finish worksheet/drawing if not completed in class
Tuesday: Spongebob Genetics, Review Game
Homework: Finish Worksheet if not completed in class
Wednesday: Spongebob Genetics 2, Ch. 5 vocabulary
Homework: Finish worksheet if not completed in class
Thursday: Spongebob Genetics Quiz, DNA Notes
Halloween Dance
Friday: Brainpops, Renaissance Party
Heredity Notes
Introduction:
For many years we have been breeding dogs, cats, horses and other animals and plants to produce offspring with desired traits. (Example: horses that can run fast, flowers that are prettier than others, dogs that have better mannerisms, etc.) We also try to breed plants that produce offspring that will produce a greater harvest, or resistant to specific diseases.
Can you think of other plants and animals that are bred or crossed for specific traits? Write a few down.
Mendel and his pea plants
If you look at yourself and try to compare yourself to others, most likely there is no one person exactly like you. Even if you have a twin, you are not exactly alike. You may resemble each other or your parents, but there is no one else exactly like you. That is what makes us all special and unique.
We will find out in this chapter, why we are not all exactly alike and how we get the traits we have that cause us to look, act, and behave different from other humans. We will focus on plants and animal traits to study this.
Gregor Mendel also wanted to know why organisms differed and what caused the differences to show up in offspring.
Why Don’t You Look Like A (Rhinoceros or any other Organism?)
Well, what do you think the answer to this topic is? If you said because your parents are not a rhinoceros or some other organism, then you are correct! You are who and what you are due to your parents. Heredity is the passing of traits, also called genes, from parents to offspring.
The person given credit for discovering this was Gregor Mendel. He worked with pea plants and bred pea plants to determine how traits are passed from one generation to another (parents to offspring). Mendel noticed some pea plants were always tall, some always short, and some always produced purple flowers, while others always produced white. Mendel questioned why this happened.
Mendel lived in a monastery during the time he studied the pea plant characteristics. Pea plants are self-pollinators. In other words, one pea plant flower has both male and female parts. The male parts produce pollen and the female part produces the egg. In this situation, pollen from one flower can fertilize the eggs of the same flower or the eggs of another flower on the same plant. With the help of an insect, wind, or other organism, the pollen can also be carried to a totally different pea plant where fertilization can occur.
When genes or traits are passed from the parent to the offspring, we say the offspring has inherited the genes from the parents. Mendel noticed, from his breeding of pea plants, that sometimes a trait from one generation would not show up in the second, but if he crossed (bred or mated) pea plants of the second generation, the traits would show back up in the third generation. Mendel noticed the same occurrences in other plants and animals also. To simplify all of his observations and try to learn what was occurring, he decided to work exclusively with the garden pea plant.
To make his research easier, he decided to study one trait at a time. He worked with one group of pea plants regarding the height of the plant from one generation to the next and in a separate experiment with different pea plants he worked with the color of flower the plants produced.
Recall from Chapter 1 (Scientific Method): When doing experiments it is best to test one variable at a time. This was what Mendel was doing by looking at height in one group of peas and flower color in a different group.
True-Breeding Plants
When a true-breeding plant pollinates itself, it always produces offspring with the same trait as the parent plant. Example: a true-breeding plant for the tall characteristic always produces tall offspring, a true-breeding plant for purple flowers always produces offspring with purple flowers.
Traits Mendel Looked at with the Pea Plants
Mendel noticed some of the pea plants produced wrinkled peas and some produced round peas. Mendel crossed a plant that produced wrinkled peas with a plant that produced round peas (these are the parent generation). The offspring from this cross is called the first generation. Mendel noticed the first generation plants produced all round peas. So Mendel concluded that the round trait must hide the wrinkled trait. Mendel called the trait that appeared; the dominant trait and the one that did not show up he called the recessive trait. Mendel then allowed the first generation to self-pollinate and the second-generation plants produced round and wrinkled seed, but he noticed for every round seed there was only one wrinkled seed.
In other words, the recessive trait showed up again in the second generation.
Mendel tested seven traits he found the pea plants to have and the following shows his results.
Characteristic Dominant Recessive
Flower color purple white
Seed color yellow green
Seed shape round wrinkled
Pod color green yellow
Pod shape smooth bumpy
Flower position along stem tip of stem
Plant Height tall short
Out of all of these traits Mendel conducted research on he noticed the result of the second-generation always had the dominant trait about three times more often than the recessive trait. So for every time a dominant trait showed up, the recessive trait showed up one time. This produces a “ratio” of 3:1.
Mendel’s Brilliant Idea
Mendel realized that the only way this could happen, was if each plant had two sets of instructions (now known as genes) for each characteristic. Mendel reasoned that each parent must contribute one gene each and the offspring would end up with two. The offspring therefore would have two forms of instruction (genes) for the same trait. Each individual form of a gene is known as alleles.
Proving His Idea was up to the Punnett Square
Mendel did not invent the Punnett Square, it was invented by a man with the last name of Punnett. A Punnett Square is a visual tool to see all the possible combinations of alleles that offspring can receive from their parents. When using a Punnett Square the dominant alleles are given a capital letter and the recessive alleles are assigned a lower case letter. Example: For flower color, Mendel noted that purple was dominant over the white recessive gene, therefore in a Punnett square purple would be assigned a “P” and white would be assigned a “p”.
How is a Punnett Square Set Up?
First, you draw a square that is large enough to divide into equal quarters and the quarters should be large enough to write the letter of the alleles into.
Try to follow this example on your own paper. We want to breed or cross a true-breeding purple pea plant “PP” with a true-breeding white pea plant “pp”. So, we would write “PP x pp”. Now for the square:
Draw a square large enough, maybe 2 inches by 2 inches and the divide it into equal units of four 1 inch by 1 inch squares.
Now we place our parents alleles on the outside of the square. One parent’s alleles will go across the top and the other will go down the side. Remember we are crossing PP x pp.
Next we bring one parents alleles down and place them into the square and bring the other parents alleles across and place then into the square.
Now we have all the possible genotypes of the offspring. In this situation all of the offspring will have Pp which is one alleles for the dominant purple and one allele for the recessive white. All of the pea plants will produce purple flowers, but carry the recessive gene for the white flower. This situation is called heterozygous (one allele for a different form of the same characteristic). This is the same type of work Mendel completed.
Now let’s see what happens if we take these offspring (first generation) and cross them together (Pp x Pp).
Now, we see the genotype possibilities are PP, Pp, Pp, and pp. For the genotypes, one is homozygous dominant “PP”, two are heterozygous “Pp”, and one has the possibility of being homozygous recessive “pp”. for the phenotypes, three have the possibility of being purple and one has a possibility of being white. So now we have Mendel’s 3:1 ratio. So in this cross, there is a 75% probability that the pea will produce purple flowers and 25% probability the offspring plant will be white flowered.
All of these probabilities are random, in other words it is entirely random as to which alleles the offspring gets and each time we breed organisms with this possibility, there is the same chance to get the same outcome. Each fertilization or cross we conduct is independently random each time. Just because we cross a pea plant three times and get offspring that has purple flowers, does not guarantee we will get a white flowered pea plant on the fourth cross we complete.
What is probability? Probability is the mathematical chance that an event will happen or occur. Probability is usually expressed as a fraction or percentage (3/4 or 75%) or a ratio can be used sometimes (3:1).
Gregor Mendel published his findings in 1865, but his ideas were not given much attention until after his death about 30 years later. We now often referr to him as the “father of modern genetics”. Genetics is the study of passing of traits from one generation to another.
Cross the Following:
1. A true- breeding purple flowered pea plant with a heterozygous pea plant. You should have visualized or determined the true-breeding plant as “PP” and the heterozygous as “Pp”, so you have PP x Pp.
2. Cross a heterozygous purple pea plant with a white pea plant.
3. Use “T” for the tall trait, and “t” for the short trait. Cross a homozygous tall plant with a homozygous short plant.
4. Cross a heterozygous tall pea plant with a homozygous tall pea plant.
5. “R” is dominant for seed shape in peas, it means round. Wrinkled is the recessive trait. Cross a homozygous round pea plant with a homozygous wrinkled pea plant.
6. Cross a heterozygous round pea plant with a homozygous round pea plant.
7. Cross a heterozygous round pea plant with a homozygous wrinkled pea plant.
8. Cross a homozygous smooth pod (smooth is dominant, bumpy is recessive) pea plant with a heterozygous smooth pod pea plant.
9. Cross a homozygous smooth pod pea plant with a homozygous bumpy pea plant, then cross the first generation and show your second generation results. Tell me what the original parents (parent generation) genotype is in this scenario.
10. Now, brown hair is dominant over blonde hair in humans. What would the genotype of a homozygous brown haired person be? What about a heterozygous brown? What about a homozygous recessive blonde? Now cross a homozygous brown haired individual with a blonde haired individual. Cross two heterozygous brown haired individuals. Make sure you show all of your work clearly.
With this information you should be able to cross organisms with different forms of the same gene at this time. This is referred to a mono-cross. Mono means one. We will learn how to cross organisms with different forms of the same gene for two different genes, which are called a di-hybrid cross. Di meaning two.
Chapter 5 Section 2 Notes
Meiosis
Recall: there are two kinds of reproduction, 1) asexual and 2) sexual reproduction.
In asexual reproduction, only one parent is needed for reproduction to occur. This is how bacteria or prokaryotic cells reproduce. They copy their genetic information and then divide (binary fission).
In sexual reproduction, you must have two parent cells known as sex cells. In males, the sex cell is the sperm. In females, the sex cell is the egg. Remember that humans have 23 pairs of chromosomes. When we look at sex cells, each one will have only 23 chromosomes so when an egg and sperm unite, we end up with 23 pairs of chromosomes again (one from the mother and one from the father). In other words, human sex cells have half the usual number of chromosomes.
For sex cells to have 23 chromosomes, they must go through a process called meiosis. Meiosis produces new cells with half the usual number of chromosomes. Simply put, when sex cells are made, the chromosomes are copied and then the nucleus divides two times. The resulting cells (egg and sperm) have half the number of chromosomes found in a normal body cell.
Location, Location, Location
What does location have to do with genes? Well, a man by the name of Walter Sutton discovered that genes are located on chromosomes. Scientists have actually located specific genes and their locations on the chromosomes.
RECALL, RECALL, RECALL the steps of mitosis because meiosis is very similar. Review mitosis for a better understanding (Interphase, Prophase, Metaphase, Anaphase, and Telophase) know what happens in each phase that we have discussed in the past.
The Process of Meiosis (remember: meiosis is for sex cells).
The following is the phases of meiosis and the major event that happens in each phase.
Interphase: during this phase the chromosomes copy themselves.
Prophase 1: the nuclear membrane disappears and the chromosomes begin to pool into the center of the cell.
Metaphase 1: the chromosomes line up on the equator or middle of the cell.
Anaphase 1: the copied pairs of chromosomes pull away from each other toward the “poles” of the cell.
Telophase 1: the nuclear membrane reforms and the cell divide taking one complete pair of chromosomes into each new cell. (Now we have two cells with 23 pairs of chromosomes).
Prophase 2: the nuclear membrane disappears and the pairs of chromosomes in each cell pool in the cell.
Metaphase 2: the pair of chromosomes line up on the equator of each cell.
Anaphase 2: the pairs of chromosomes pull apart and move to the poles of each cell. (23 chromosomes move one direction and 23 move the other direction).
Telophase 2: the two cells form cleavage furrows, nuclear membranes reform and each cell divides to end up with four cells total and each cell has 23 chromosomes. Each new cell has half the number of chromosomes present in the original cell.
QUESTION: Does this process resemble anything we studied before? What does it resemble?
Meiosis review:
1. In a human, how many chromosomes are in the original single cell before meiosis?
2. In a human, how many times do chromosomes make copies of themselves in meiosis?
3. In a human, how many times do cells divide in meiosis?
4. In a human, how many chromosomes are in the cells at the end of meiosis?
5. In a human, how many chromosomes are in the cells at the end of mitosis?
Meiosis Review Answers
1. In a human, there are 23 pairs of chromosomes or 46 chromosomes in the original single cell before Interphase begins. At the end of Interphase, there are 46 pairs of chromosomes or 92 chromosomes. At the end of Telophase 1 there are 23 pairs or 46 chromosomes in each cell. At the end of Telophase 2, there are 23 chromosomes in each cell and we have four cells total.
2. In a human, chromosomes copy themselves only one time in meiosis.
3. In a human, cells divide in meiosis two times. (Once in Telophase 1 and once in Telophase 2).
4. In a human, there are 23 chromosomes in each of the four cells after the completion of meiosis.
5. In a human, there are 23 pairs (46 chromosomes) in each cell at the end of mitosis.
Male or Female?
In humans we have 23 pairs of chromosomes. Twenty-two of those pairs are called autosomes, but one pair is called sex chromosomes. The reason they are called sex chromosomes is because these chromosomes determine if you are a male or female.
The sex chromosomes resemble an “X” or a “Y”. Remember we get one from our father and one from our mother, so we have two sex chromosomes. If a person has two X’s (XX), then the person is a female. If the person has an X and a Y (XY), then the person is a male.
In simple terms, the female can contribute an X sex chromosome and the male may contribute an X or a Y to the offspring. Experiment: Cross a male and female in a Punnett square to see the probability of having a male or female offspring. What did you get? Remember, it is random as to which sex chromosomes become fertilized together so we can only give probabilities that an offspring will be male or female by using Punnett squares.
We have become so technologically advanced that we can remove some of the cells from an embryo prior to birth and look at the sex chromosomes to determine if a male or female has been conceived. We also have ultrasound tests that can give us a picture of the fetus and knowing what to look for, we can tell if the child will be a male or female.
Posted by: Team 7.2 Science
| @ October 18, 2009 10:32:13 PM EDT ( ) |
Monday: Fall Break
Tuesday: Fall Break
Wednesday: Human Body Systems games/ CRCT Coach book Review
Thursday: Computer Lab: Study Island/ Human Body Vocab
Friday: Human Body Systems quiz
For 10 points off, students can turn their body systems books in on Wed.
***For each of the 12 systems
1)Draw a diagram of each system and label
2)Describe the functions and organs of each system
3)Explain how each system works with other organ systems
4)List 4 facts about each system
Section 1: Body Organization
Recall: The maintenance of a stable internal environment is called homeostasis. If homeostasis is not maintained, cells are often damaged and can die from the damage. These cells make up tissues, so in effect the tissues can die and as the organization levels occur, the organism can ultimately die.
Tissue Types
There are four types of tissue: 1) Epithelial Tissue – this tissue covers and protects underlying tissue 2) Nervous Tissue – this tissue sends electrical signals from the point of a stimulus to the brain in order to react to the stimulus if necessary 3) Skeletal Muscle Tissue – this tissue is made of cells capable of contracting and relaxing that can produce movement within or of our body 4) Connective Tissue – this tissue joins, supports, protects, insulates, nourishes, and cushions organs and keeps organs from falling apart.
Recall that two or more tissues working together will form an organ. Our stomach has all four types of tissues that make it up (the stomach therefore is an organ). The stomach has blood vessels which is connective tissue, it contains epithelial tissue to cover the lining, it has nervous tissue (tell us when we are hungry or full), and it contains muscle tissue that expands and contracts to break up the food we ingest (eat).
Recall organs make up organ systems. When any organ fails, the body’s organ systems can fail. We have 11 organ systems.
The 11 Organ Systems (We will look at these in great detail)
1: Integumentary System – made up of our skin, hair and nails. This system helps protect underlying tissue(s).
2: Muscular System – Your skeletal muscles move your bones and this allows us to move from one place to another if our body is functioning properly.
3: Skeletal System – this is made up of your bones. Our bones provide support. If we didn’t have bones we would be one ugly blob with no shape.
4: Cardiovascular System – composed of our heart, and blood vessels (arteries and veins). Transports blood with nutrients and wastes.
5: Nervous System – this system sends electrical impulses throughout our body (nerves, spinal cord, and brain).
6: Lymphatic System – this system includes lymph nodes and lymph vessels and helps us with immunity and getting rid of germs.
7: Digestive System – Breaks down food we eat into nutrients that our body can use.
8: Endocrine System – Composed of glands that secrete hormones (chemical messages) for specific actions in our body (pituitary gland, thyroid gland and testies for males, and ovaries for females to name a few of the glands in our body).
9: Respiratory System – our lungs absorb oxygen and release carbon dioxide.
10: Urinary System – removes wastes from our blood and regulates fluids in our body.
11: Reproductive System: In males it produces and releases sperm. In females it produces eggs and provides a development site for an unborn baby.
Review
1. Explain the organization level and relationship between cells, tissues, organs, and organ systems.
2. Compare the four types of tissues and their function.
3. Without looking at your notes, make yourself a chart listing all of the major organ systems and their function.
Answers to Review
1. Cells make up tissues, tissues make up organs, organs make up organ systems and organ systems is what make up an organism. Cells work together to make tissues. Tissues work together to make organs. Organs work together to make organ systems. Organ systems make up organisms.
2. Nervous Tissue – sends electrical signals (impulses) for stimuli, Epithelial – covers and lines in order to protect underlying tissue, Muscle – cells contract and expand to produce movement, Connective Tissue – joins, supports, protects, insulates, nourishes, cushions, and keeps organs from falling apart.
3. Compare your chart to the notes you have learned.
Applying what you learned
Think of a time when homeostasis in your body was disrupted. Which body system(s) were affected? Explain your reasoning.
IMPORTANT: As we learn details about each system always make yourself learn the NAME, LOCATION, and FUNCTION. Example: Name: nervous system, Location: spinal cord, nerves, brain, Function: to send electrical impulses for reactions to stimuli or other needed reactions (walking, talking, etc.).
Section 2
The Skeletal System
Our bones and cartilage and the special structures that connect them make up our skeletal system. If we did not have our skeleton for support we would be a mass or blob so to speak. Our skeleton or bones are living cells. They must be nourished because they are made up of cells. These special cells are called osteocytes and they mage up our bone tissue.
Functions of Our Bones
1) Protection - the vital organs in our chest (heart and lungs) are protected with our ribs, our spinal cord is protected by our vertebrae, and our brain is protected by our skull.
2) Storage - bones store minerals that help the nerves and muscles function properly. Your arm and leg bones store fat that can be used for energy.
3) Movement – Muscles pull on the skeleton in specific locations to produce movement. Without the bones we also could not sit, stand, walk, or run.
4) Blood Cell Formation – Some of our bones are filled with marrow that produces blood cells.
Bone is composed of connective tissue and minerals that are deposited by living cells called osteoblasts. If we looked at a section of our longest bone (the femur) in our thigh, we would find spongy bone and compact bone. These are found in all of our long bones. Compact bone is dense and has no visible openings. Spongy bone appears to look like a real fine sponge with air spaces. Spongy bone is where we get most of the strength for our bones. The “spongy” configuration acts as a truss structure analogous to what we would see in a building made of steel.
Marrow
The soft tissue in the bone is called marrow and red marrow produces red blood cells.Yellow marrow found in the center of the bone (central canal) of long bones stores fat. The canals in the compact bone contain small blood vessels.
Bone Information
Most bones start out as soft, flexible tissue called cartilage. As a new born baby, we had very little bone. We were mostly cartilage. As we became older, the cartilage was replaced by bone.
The location where two or more bones connect is called a joint. These joints have unique designs that will allow movement from some joints and little or no movement from others. Joints that are freely moving are more susceptible to injury than those that are less flexible.
Joints are held together by ligaments that are connecting bone to bone. A strained ligament will heal if given time, but a torn ligament must be repaired surgically. Most bones also have cartilage on the ends to help cushion the area where two bones meet. When this cartilage is worn away, the joint becomes arthritic. This can create discomfort for the individual with arthritis.
Types of Joints
1. Sliding Joint – this type of joint allows some movement of flexibility. The bones in this type of joint glide over each other. Example: the bones in your wrist.
2. Ball and Socket – this operates like a joystick on a computer game, the joint is free to move in all directions. Example: your shoulder joint.
3. Hinge Joint – this operates like a hinge on a door. Example: Knee joint, knuckles, toes, jaw and elbow joint.
How Bones Function to Help Movement
Bones function like a simple machine called a lever. The lever has three parts: fulcrum, effort, and the load. The effort is the force applied to the lever, the fulcrum is the pivot point and the load is the resistance.
Review
1. What are the important functions of bones?
2. Draw a long bone like a femur that has a section removed and label the parts (spongy bone, compact bone, areas for blood vessels, marrow cavity, and cartilage).
3. List three hinge joints in your body.
4. Are bones living? What do bones begin as? What do we call the cells that deposit bones? Where are red blood cells produced? Some bones store fat, what is it used for?
5. What is a function of cartilage on the ends of bones?
Answers
1. Bones provide support, store and release minerals, enables us to move our bodies, and make blood cells.
2. Compare your drawing to the bone on page 527 in our classroom text.
3. Hinge joints can include the elbow, knee, jaw, knuckles and toes.
4. Bones are living, they require nourishment like other tissues in our body. Bones start out as cartilage. The cells that deposit bones are called osteoblasts. Red blood cells are produced in the red marrow. The fat can be used as a source for energy.
5. Cartilage can serve as a cushioning source when it is located at the end of long bones.
Section 3
The Muscular System
Muscles attach to bones and the connective tissue that attaches them make up the muscular system. Remember: Muscles ALWAYS contract to do work. In other words, for muscles to do work, the muscle fiber must contract (get shorter).
Types of Muscle Tissues
1) Smooth Muscle – this is found in the digestive tract and your blood vessels. 2) Cardiac Muscle – this is heart muscle (found only in the muscle tissues of your heart). 3) Skeletal Muscles – these are the muscles attached to your bones for movement and protecting inner organs.
Voluntary or Involuntary Muscle
Muscles that are under your control are voluntary muscles. The muscles used to pick up a pencil when you want to write are voluntary muscles (you are controlling their actions). Muscles that digest food, move food through your digestive system (smooth) and cardiac muscles are examples of involuntary muscles (you do not have to think about making these muscles take action).
Some may fall into voluntary and involuntary (example: eyelids – sometimes you control your blinking, other times you blink and do not realize you have blinked).
Working Muscles
When you want your muscles to contract and make you walk you must have electrical signals traveling from your brain to your muscle cells. The muscle cells respond by contracting (shortening). Remember, muscles only do work when their fibers are contracting.
Muscles to Bones
Your skeletal muscles are attached to your bones by a connective tissue called tendons. When the muscles contract, they get shorter and bring the bones closer to each other, hence producing movement.
Muscles always work in Pairs
Muscles work in pairs, resulting in smooth controlled movements. Example: Your Biceps (upper arm muscle in the front) can contract and cause our arm to bend at our elbow. The triceps (back of upper arm) can contract to straighten our arm back out. The muscle that is causing the bending movement is called the flexor, and the muscle that straightens out a part of the body is called the extensor. So in the above example, the biceps is the flexor and the triceps is the extensor.
Use It or Lose It
If you do not use your muscles, the muscle tissue will deteriorate. We must use our muscles in order to keep them “tone” and in order to build them up and become stronger. If you know someone with a broken bone and they wear a cast, the muscles not being used will become weaker and will have to be strengthened when the cast is removed.
Muscles also aid in the circulation of blood and lymphatic fluid. When muscles contract, the action constricts the vessels and “pushes” blood and lymph in their respected vessels. This helps blood flow without extra effort from the heart.
Exercise
In order to maintain muscle or build muscle, we have to be active and exercise. The most effective exercise is resistance exercise. This is where the muscle contracts to move an object and the object offers resistance. The process of lifting our bodies vertically offers one method of resistance. An example of this type of exercise would include climbing steps, push-ups, sit-ups, pull-ups and other motions that use our own weight as the resistance weight. Resistance exercises are often hard to maintain long periods of time, but they offer one of the best methods of building muscle.
Aerobic Exercise
Aerobic – with oxygen. Aerobic exercise is great for our cardiovascular system. This strengthens the heart muscle and will increase the lung capacity and the effectiveness of our lungs. Aerobic exercises do not necessarily strengthen skeletal muscles, but increases our endurance.
Damaging Muscle Tissue
Before taking part in any physical exercise program, our muscles need to be warmed and stretched. Stretching can do this. Taking in deep breaths while stretching also increases the oxygen content in our bodies. After stretching and giving our muscles a warm-up reduces the chance for a muscle injury. When we “pull a muscle” we may be straining it or the muscle fibers can actually tear. We can also damage tendons. The tendons can become inflamed (irritated) and the area may feel warmer than the surrounding tissue. This type of tendon injury is called tendonitis.
Anabolic Steroid Use
This has become all too common in the area of sports. Taking the anabolic steroids can make our muscles larger and stronger and gives many athletes an unfair advantage. We are now seeing the effects of using anabolic steroids. Many athletes have died from having an enlarged heart as well as other complications from using anabolic steroids. If a person has not fully developed it may also cause bones to stop growing, high blood pressure, kidney failure and liver and heart problems. Anyone taking these steroids are at risk for an early death or a very unhealthy life due to the negative affects.
Review
1: What are the three types of muscle tissue and give a few locations you can find each type. Give the main functions of each type of muscle tissue.
2: What are the differences and similarities between resistance and aerobic exercising and give a few examples of each. Can they both be the same in certain instances?
3: Describe or explain how the muscles in your arm allow you to pick up a glass from a table to your mouth for a drink.
Answers:
1: Smooth muscle tissue helps move materials through the digestive tract and blood vessels; cardiac muscles cause the heart to beat; and skeletal muscles enables bones to move.
2: Resistance exercises increase our strength of skeletal muscles. Resistance exercises involve overcoming weight of some type. Aerobic exercises improve the condition of heart muscle and increase our endurance.
3: Our biceps contract in order for our arm to bend and bring the glass up to our mouth to drink. Our triceps contract in order to straighten our arm back out and set the drink back onto the table.
Section 4
The Integumentary System
The integumentary system is for protection and includes our hair, nails, and skin. Our skin is the largest organ of all the organs our bodies have. Integumentary means covering. The integumentary system also helps your body to maintain homeostasis. Remember from chapter 1: homeostasis is a stable internal environment.
Functions of the Skin
1) Protects our bodies from evaporation and helps keep foreign particles out of the body.
2) Keeps us in “touch” with our environment. The nerve endings in our skin allow us to fell what is around us.
3) Our skin helps to maintain our body temperature. We have sweat glands in our skin that will sweat and when the sweat evaporates, it cools our body.
4) Our skin also helps rid our bodies of waste products from the blood stream by way of the sweat.
Skin Color
A pigment in our skin called melanin determines the color of our skin. If we have a lot of melanin, our skin is very dark. If a small amount of melanin is produced, our skin will be very light. Melanin in the upper layer of the skin protects us by absorbing much of the ultraviolet radiation from the sun, which reduces the DNA damage that can lead to cancer. All of our skin is susceptible to cancer so protection should be taken when we spend time outside. Proper skin suntan lotion should be used and the lotion should contain a SPF protection of at least 30.
Layers of Skin
The skin is the largest organ of our body and it has two layers. The epidermis is the upper layer and is thinner than the second layer. “Epi” means above or top. The deeper layer is called the dermis. It is thicker than the epidermis.
Epidermis
Composed of epithelial tissue. It is about as thick as two pieces of notebook paper over the most of our body. Our palms of our hands and soles of our feet have thicker layers of epidermal cells. Most epidermal cells are dead and filled with keratin which helps the skin be tough and water-proof.
Dermis
Found beneath the epidermis. It contains many connective tissue fibers called collagen. This provides strength and allows the skin to bend without tearing.
Hair and Nails
Hair is grown from the hair follicle and the portion we see is actually dead cells. As hair grows from the follicle, cells are pushed up and form the portion we see.
Hair protects us from ultraviolet radiation and also helps keep dust and other particles out of our eyes and nose. Hair also helps maintain internal body temperature. Many mammals rely on their hair to keep them warm in very cold climates. Humans form “goose bumps” on our skin when we get cold. This occurs when a muscle connected close to the hair follicle contracts and the hair stands up in an erect position. The erected hairs act like a sweater to trap heat which warms the body.
Our nails protect the ends of our toes and fingers so they can remain sensitive to touch. Our nails grow from nail roots. The nails we see are dead cells. As cells grow from the root, the nail gets longer.
Skin Cancer and other Problems
Sometimes skin cells become damaged and the cells rapidly multiply out of control. When cells go through the cell cycle at a rate faster than normal we call that cancer. This can also invade other tissues and result in cancer spreading.
A common problem many individuals face is having hormones cause too much oil being produced by the skin cell oil glands and creating a situation for infections. The oil may cause skin cells and bacteria to clog up the follicle and when the bacteria multiply you have an infection. Washing our skin well each day can usually prevent this type of infection.
REVIEW
1: Why does skin color vary from person to person?
2: List as many structures as you can that are found in the skin and give the function of each one.
ANSWERS
1: The amount of melanin produced regulated the skin color.
2: Hair follicle, blood vessels, nerves, oil glands, sweat glands, keratin for water proofing and flexibility, fat cells to help conserve temperature and can be used as energy sources if needed.
Posted by: Team 7.2 Science
| @ October 5, 2009 12:40:46 AM EDT ( ) |
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