THE Living Environment Cheat Sheet

LIVING ENVIRONMENT REVIEW TOPICS

2012-01-17T09:33:00.000-08:00

EDUSOLUTION REVIEW SITE

INQUIRY1/SCIENTIFIC METHOD

INQUIRY2/SCIENTIFIC METHOD

CELLS ORGANELLES/HOMEOSTASIS

ORGANIZATION

ECOLOGY

HUMAN IMPACT ON THE ENVIRONMENT

MITOSIS

MEIOSIS

NATURAL SELECTION

HUMAN REPRODUCTION

MULTIPLE CHOICE TEST TAKING TIPS
REDUCING TEST TAKING ANXIETY

EVOLUTION

GENETICS

GENETIC ENGINEERING/DNA TECHNOLOGY

THE SYSTEMS AND HOMEOSTASIS

IMMUNE SYSTEM

CLASSIFICATION

DIFFUSION LAB

CELL DIVISION2

Natural Selection/Evolution

2012-01-09T11:12:00.000-08:00

EVOLUTION, what is it?

- organisms change over time.

How do organisms evolve?

- in order for the organism to evolve, it must first survive.

- Extinct organisms do NOT evolve.

How is evolution explained?
- Scientists use fossils as evidence to explain evolution.

- Fossils are evidence of past life. Example below:

What was the first organism to inhabit this planet?

- The first organism to inhabit this planet was bacteria. Example below:

According to Darwin... (His explanation of natural selection)

1. In nature, organisms produce more offspring than will survive.
2. In any population, there is always variations among species
3. Individuals with favorable variations or traits survive the environment, passing on those variations or traits to the next generation
4. Overtime, offspring with certain variations make up most of the population and may look entirely different from their ancestors.

What are the mechanisms that drive evolution?

- In order to evolve, the organism must live or be selected.

- The environment is the selecting agent

- The mechanisms that drive evolution are mutations and genetic recombination through sexual reproduction

Problem

Use Darwin's theory of natural selection to explain why some bacteria that was once susceptible to certain antibiotics are becoming resistant.

Answer:

-Populations of bacteria produced more offspring than will survive
-In any given population of bacteria there is variation, like resistance to antibiotics.
-Bacteria with favorable traits, like resistance to antibiotics survive, reproduce and pass on the traits.
-Overtime, resistant bacteria make make up most of the population because they are the ones that survived.

How does over-crowdedness lead to natural selection?
- Over-crowdedness leads to competition. During competition, organisms that have favorable traits survive, reproduce and pass on those traits.

What are traits?

- Traits are your characteristics.

- Ex, skin color, eye color and height.

VOCAB:Camouflage is when the organism blends in with the environment. This trait helps the organism survive by allowing the organism to escape predators or become less visible to its preys.

Adaptive traits are any structural or physiological characteristics that help the organism survive the environment.

BACK TO TOPICS

CELL DIVISION/MITOSIS

2010-04-21T03:26:00.000-07:00

What is mitosis?

What comes to mind when you think about mitosis?

Mitosis is a cell division

that produces two daughter cells which are identical (the same) or when the cell makes an identical copy of itself
Cells produced by mitosis are identical in chromosome number and in chromosome combination. An example is below:

Why do cells undergo mitosis?

Some cells use mitosis as a means of reproduction. For instance, single-cell organisms reproduce by mitosis. This is a form of asexual reproduction where the genes come from one parent.
There are some multicellular organisms that are able to use mitosis as a means of reproduction.
Multicellular organisms use mitosis for growth. In other words for the replacement of injured cells and for the replacement of dead cells. For example, in humans after the egg is fertilized, mitotic cell division is used to make all of the structures that are necessary for a human to function (heart, brain, legs...)

MITOSIS POWER POINT PRESENTATION

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MITOSIS Animation

Want to learn more about mitosis? Check out the links below!
MITOSIS TUTORIAL

MITOSIS IN A PLANT CELL

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What are the types of cell division?

mitosis
meiosis
binary fission.

Why do cells divide?

Cells divide for growth
Cells divide to replace injured cells, for instance when you cut yourself.
Cells divide to replace old cells that died

What about humans and other multicellular organisms?

All of the body cells found in humans and other multicellular organisms are made by mitosis.
For instance, your skin, your bones, liver, lungs, hair etc.. are all products of mitosis.
These cells do not look alike and do not have the same functions but they are identical in chromosome numbers and chromosomes combination.

How is it possible that cells with same DNA do not look identical and do not have the same function?

The DNA refers to all of the organism's genes. However, some genes are active in some cells and not active in others. For example, the bone cells have the gene for becoming a skin cell, but they do not activate this gene; instead, they focus on the gene that will allow them to become a bone cell.
This concept of becoming a task specialist is called differentiation.

How would humans be different, if we were to reproduce by mitosis?

Compare the advantage to the disadvantage of reproducing by mitosis.

How can you use this information?

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Want to learn more about mitosis? Check out the links below!
MITOSIS TUTORIAL MITOSIS IN PLANT CELL

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Make a connection:
Binary Fission is similar to mitosis, it produces two identical cells. This type of cell division only occurs in bacteria

DON'T FORGET!

Cells produced by mitosis may not look alike, but they are identical in chromosome numbers and combination.
Mitosis produces two genetically identical daughter cells.
Organisms that reproduce asexually, reproduce by mitosis

CANCER IS UNCONTROLLABLE MITOSIS
Cancer cells continuously divide and do not undergo cell death.

Why do you think that cancer usually causes people to lose weight?

To learn more, click this link. CANCER MOVIE

Use this hands on game to help deepen your understanding of mitosis

MITOSIS INTERACTIVE

BACK TO TOPICS

CELL DIVISION/MEIOSIS

2010-04-20T03:52:00.000-07:00

What is meiosis?

Meiosis is a cell division that produces the sex cells or the gametes.

Meiosis produces four daughter cells that are NOT IDENTICAL (not the same).

Sometimes meiosis is referred to as the reduction of the chromosomes because cells that are produced by meiosis have half the number of chromosomes as the parent cells.

Note: Only the sex cells are produced by meiosis

Meiosis only takes place in the testis of males and ovaries of females

For more of description, click on this:

MEIOSIS POWER POINT PRESENTATION

List three events that occur in meiosis that are responsible for diversity in sexually reproducing organisms.

Crossing-over
Independent assortment
Two consecutive cell divisions

What are sex cells?

Sex cells or gametes are the sperms and the eggs.

These cells have half the number of chromosomes as the body cells.

Additionally, each of the sperm cells or the eggs has a different combination of chromosomes.

The male sex cells or sperms are produced in the male testis, and the female sex cells or eggs are produced in the female ovaries.

-How are sperm cells different from egg cells?
-How are they similar?

LOOK AT THESE SPERM CELLS!

CHECK OUT THIS EGG CELL!

Where do you get your genes from?

You inherit (get) your genes from your parents.

You receive half of your genes from your mom and the other half from your dad.

The sperm brings the half from your dad and the egg brings the half from you mom.

If you and your siblings are receiving genes from the same parents, how come you are not identical?

HEREDITY: IS THE PASSING OF TRAITS FROM PARENTS TO OFFSPRING

NOTE: CELLS PRODUCED BY MEIOSIS EACH HAS A UNIQUE COMBINATION

For example, each time a man ejaculates, he releases 3 million to 5 million sperms and each sperm has a different combination.

Why do you think it is necessary for a man to release so many sperms?

How are cells produced by mitosis different from cells produced by meiosis?

Cells produced by mitosis have a full set of chromosomes.

Cells produced by meiosis have half the number of chromosomes as the parent cell.

Learn more here:

Mitosis vs Meiosis Animation

Learn even more here!
MITOSIS VS MEIOSIS 2

What are three types of reproduction?

Asexual reproduction

Sexual reproduction

Cloning.

How is a asexual reproduction different from sexual reproduction?

Asexual reproduction involves just one parent and the offspring are identical to the parent.

Sexual reproduction involves two parents and the offspring are similar, but not identical either parent.

What are some advantages of sexual reproduction?

What are some disadvantages of sexual reproduction?

What are some advantages of asexual reproduction?

What are some disadvantages of asexual reproduction?

What are 3 types of asexual reproduction?

fragmentation

binary fission

budding.

Fragmentation Occurs in star fish. For instance, if you step on a star fish and break in four pieces, as long as each part contains portion of the nucleus, each part of the star fish will become a new organism.

Budding Some organisms like certain plants are able to form a bud. This bud can fall to the ground and grow to become a new plant.

Binary fission A process similar to mitosis that bacteria use to reproduce

What is FERTILIZATION?

Fertilization is the union of the sperm and the egg. Zygote is the new cell that is formed by the egg and the sperm.

What is cloning?

Cloning is a technique that produces the same end result as asexual reproduction.Cloning produces organisms that are identical. This procedure involves the removal of nucleus from one cell and placing it into another cell.

Is there an advantage to sexual reproduction?
Yes, Sexual reproduction creates differences or diversity. Because sexual reproduction creates so many different combination, when the environment changes, there is a better chance that some organisms will survive.

Yes, If two members of the same family are exposed to H1N1, however, it is possible that only one of them dies from the disease and the other member is not affected. If they were identical, if one dies, the other would also die. Sexual reproduction increases the chances for survival when there is change in the environment.

Is there a disadvantage to sexual reproduction?

You cannot guaranty the expression of the desirable trait.
Undesirable recessive traits may be expressed.

REVIEW QUESTIONS

What is mitosis?

Mitosis is a cell division that produces two daughter cells that are identical.

What is meiosis?

Meiosis is a cell division that produces the sex cells or the gametes.

Where does meiosis occur?

Meiosis only occurs in the male testis and the female ovaries.

How are cells produced by mitosis different from cells produced by meiosis?

Cells produced by mitosis have a full set of chromosomes and cells produced by meiosis have half the number of chromosomes.

What comes first mitosis or meiosis?

First, we must acknowledge that meiosis only occurs in sexually reproducing organisms. Since the first life forms were asexually reproducing organisms, we must acknowledge that meiosis is an evolutionary trait. Therefore, it is logical to conclude that mitosis came first.

Where does fertilization occur?

Fertilization occurs in the fallopian tube or oviduct.

What happens after the egg is fertilized?

The new cell, the zygote moves to the uterus where the baby will grow and develop through mitotic cell division.

The order of the events are:
First, meiosis make the sperms and the eggs. Second, fertilization unites the sperm and the egg, forming the zygote. Third, after the zygote is formed, mitosis takes over and build up the organism.

The most important thing to remember about meiosis is:

It reduces the chromosome number in half.
It is one of the mechanisms responsible for the diversity or differences in organisms and that is because each sperm or egg created by meiosis is different.

THINK!
How would the world be different, if humans could only reproduce asexually?

What would be some of the social implications?

What would be some political implications?

BACK TO TOPICS

ECOLOGY (ORGANISMS AND THEIR ENVIRONMENT)

2010-04-13T10:39:00.000-07:00

What is ecology?
Ecology is the scientific study of how living things interact with the environment

Autotrophs are producers and producers are organisms that make their own food. They are the only organisms that can convert solar energy into chemical energy or food (organic compound). They carry out autotrophic nutrition. Plants and algae are autotrophs.

Auto: means self

Troph: means feeder

Autotrophs are self-feeders

PLANTS ARE AUTOTROPHS. (They make their own food)

ALGAE ARE AUTOTROPHS (They make their own food)

Scientists estimated that about 65 - 85% of the oxygen we breathe comes from algae.

Heterotrophs are consumers and consumers are organisms that eat or obtain nutrients made by autotrophs. They depend on autotrophs for food. Horses, cows, lions and humans are heterotrophs.

Herbivores are heterotrophs that eat plants only, EX. COWS .

A COW IS A HERBIVORE.

Carnivores are heterotrophs that eat meat only, ex. lions.

A LION IS A CARNIVORE.

Omnivores are heterotrophs that eat both meat and plants, ex. humans.

HUMANS ARE OMNIVORES.

Decomposers are organisms that break down dead organisms and return them to the soil. They recycle nutrients. Ex. of decomposers are fungi and bacteria.

MUSHROOMS ARE DECOMPOSERS. (mushrooms are fungi)

Predators are organism that kill other organisms for food, ex. a lion is a predator.

Prey are organisms that are killed and eaten by other organism, ex. deers are killed and eaten by lions. Deers are preys.

Scavengers are heterotrophs that eat dead organisms, Ex. vultures.

Biotic are living things.

Abiotic are nonliving.

Niche is the role that the organism play in the environment. For example, a lion's role is "predator"

Habitat is the place where organisms live.

Carrying Capacity refers to the maximum number of organism a habitat can support. Once the number of organisms reaches the carrying capacity, it levels out or stop growing.

Limiting Factors refers to any biotic or abiotic aspect of the environment that affect population growth. For example, in a desert, water and temperature are abiotic limiting factors; food, prey, and predator are biotic factors that can affect population growth.

Species Two organisms are of the same species if the can reproduce (make babies or offspring) and their babies are fertile. That is their babies can also make babies.

Population: Organisms of the same species living at the same place at the same time, for example a population of dogs, a population of cats.

Community: Different populations living at the same place and at the same time. For example, we live in a community made up of people, cats, dogs, trees, other animals and plants.

Ecosystem consist of the living and the nonliving

THINK! Provide an explanation that justifies that a person is a community.

The Food Chain And The Food Web show how energy moves through the ecosystem.

EXAMPLE OF FOOD CHAIN

Energy for this food web comes from the sun.

THINK! The arrow in the food chain or the food web represents energy. The caterpillar is receiving its energy from the flowers by eating them.

What happens to the owl population if the snake population is removed from the food chain?

How is the caterpillar population affected by the removal of the snake population?

EXAMPLE OF FOOD WEB

THINK!

How is the rabbit population affected if the deer population is removed from the food web?

INTERACTIVE FOOD WEB 1

INTERACTIVE FOOOD WEB 2

INTERACTIVE FOOD WEB 3

The first organism in the food chain or the food web is always a plant because only plants can convert sunlight into food.

In the next level in the food chain or web are the herbivores because herbivores eat plants.

Carnivores are found on the third level or higher because they eat herbivores or other carnivores.

The arrow in the food chain or food web represents energy

Energy decreases as it goes through the ecosystem because energy is used for life functions and energy is lost as heat.

- If you remove an organism from the environment, the environment becomes less stable.

- The greater the biodiversity, the more stable the environment.

Questions

Why are plants at the bottom of the food pyramid?
What happens to energy as it goes through the ecosystem?

In the food web, how come no arrow is pointed toward the plant?

What is the role of decomposers?
Identify two organisms that carry out decomposition.
What does the arrow represent in the food web?

At what level of the energy pyramid would you find the largest amount of biomass?

Answers

Plants are at the bottom of the food pyramid because they can convert sunlight into food for animals.
The decomposers recycle nutrients, or break down dead organisms and return them into the soil so that they can be used by plants.
Fungi and bacteria carry out decomposition
In the food web, the arrow represents energy.

The largest amount of biomass is found at the bottom of the energy pyramid.

Remember

Living things depend on biotic factors such as food and abiotic factors like oxygen, soil, temperature, light and water.

Ecological succession refers to the orderly changes that take place in an ecosystem, where one group or organisms is being replaced by another.

Renewable resources are resources that can recycle themselves within a short amount of time. Example: trees, animals, humans, water, oxygen are renewable resources.

Nonrenewable resources are resources that cannot recycle themselves in a short amount of time, and therefore efforts must be made to conserve them. Fossil fuel like gasoline, coal and cooking gas are nonrenewable resources.

BACK TO TOPICS

Cell Organelles/Homeostasis

2010-04-12T09:31:00.000-07:00

ALL LIVING THINGS ARE MADE OF CELLS.

The cell theory

Cell is basic unit of living things.
All organisms are made of cells.
All cells come from other cells.

IMAGE OF PLANT CELL

IMAGE OF ANIMAL CELL

There are two BASIC CELL TYPES: eukaryote and prokaryote.

INTERACTIVE ANIMATION
OF
PROKARYOTE VS EUKARYOTE

-Eukaryote cells have nucleus
-Prokaryote cells DO NOT have a nucleus. ONLY bacteria are prokaryote.

Functions of some cells in eukaryote organisms
(The roles that some of your cells play in the body)

red blood cells carry oxygen to cells and carry carbon dioxide to the lungs.
White blood cells fight germs like viruses and bacteria.
Muscle cells specialize in contraction and are used for movement.
Nerve cells carry nerve signals or nerve impulses that are used for communication.

Organelles are membrane bound structures found inside eukaryote cells. (Little organs inside the cell)
HARE ARE SOME OF THE ORGANELLES FOUND INSIDE THE CELL.

THE NUCLEUS

Nucleus: Holds the DNA and directs or controls all activities needed to maintain homeostasis. (found in both in plant and animal cells)
Nucleolus: makes ribosomes (located inside the nucleus)

THE RIBOSOMES

Ribosomes: make proteins or is involved in protein synthesis. (found in all cells) looks like dots

THE MITOCHONDRIA

Mitochondria: converts glucose and oxygen into a form of energy usable by the cell called ATP. (found in both plant and animal cells)

Cell respiration: is the process that occurs inside the mitochondria where glucose is converted into a form of energy usable by the cell called "ATP".

The formula for cell respiration is: O2 + glucose Change to: ATP + CO2 + H2O

THE CHLOROPLAST

Chloroplast: a structure found in plant cells that converts sunlight, carbon dioxide and water into glucose and oxygen. This process is called photosynthesis.
(found only in photosynthetic organisms, mostly plants)

PHOTOSYNTHESIS VIDEO

VIDEO OF PHOTOSYNTHESIS2

ANIMATION OF PHOTOSYNTHESIS3

The formula for photosynthesis is: Light + CO2 + H2O Change to: O2 + glucose

THE CELL MEMBRANE

Cell Membrane: controls what goes in and out of the cell. (found in all cells)

CHECK THIS INTERACTIVE (construction of the cell membrane)

Cell Wall: structure that makes up the outside border of plant cells, which helps the cell maintain its shape. (found in plant cells)

THE VACUOLE

Vacuole: structure found in plant cells that stores materials. (found in plant cells)

Lysosomes: have digestive enzymes that breakdown things like bacteria, viruses and old organelles.

Golgi Apparatus: Is considered the post office of the cell. It receives, stores, modifies, packages and ships newly synthesized or newly made proteins to different destinations in the cell. VIDEO OF THE GOLGI

THE ROUGH ENDOPLASMIC RETICULUM

Rough Endoplasmic Reticulum(RER): Organelle that forms a network of tubules. The RER is an extension of the nuclear envelop. It appears grainy because it is studded with ribosomes. This structure is involved in protein synthesis and export.

Smooth Endoplasmic Reticulum(SER): This structure is involved in lipid and steroid synthesis, metabolizes carbohydrates and steroids, regulates calcium concentration and is also involved in detoxification.

Receptors: are special proteins found on cell surface and they are used for communications. They interact with hormones from the endocrine glands and neurotransmitters from nerve cells.

INSIDE A CELL

CELLS ALIVE

CELL GAMES AND QUIZZES

CLICK HERE TO SEE ANIMATION OF RECEPTORS.

INTERACTIVE PARTS OF THE CELL

POWER POINT PRESENTATION OF CELL RESPIRATION & PHOTOSYNTHESIS

Enzymes: are special proteins that make it easier for chemical reactions to occur inside an organism. How well an enzyme works depends on environmental factors such as pH and temperature.

INTERACTIVE ENZYME1

ENVIRONMENTAL FACTORS ON ENZYME ACTIVITIES

pH AND ENZYME FUNCTION

WHAT PROCESSES CONTROL THE FLOW OF MATERIALS IN AND OUT OF THE CELL?

Diffusion is a process that allows materials to move in and out of the cell based on their concentration. Diffusion occurs when molecules move from an area of high concentration to an area of low concentration without using any energy. The molecules bounce against each other and spread. The molecules must be small enough to go through the holes in the cell membrane.

Active transport is process that allows molecules to move in and out of the from an area of low concentration to an area of high concentration and requires energy and the assistance of a transport protein.

To learn more, click this link. CELL ANIMATION VIDEO

Another cell animation CELL ANIMATION

BACK TO TOPICS

Organization of Living Things

2010-04-11T10:14:00.000-07:00

How are living things organized?

In order for us to discuss organization of living things, we must begin with the most basic cell, which is a prokaryote.

Prokaryotic cells are cells without organelles. The only known prokaryotes are bacteria.

Pro - means before
Karyote - means nucleus

According to fossil records, prokaryotes (bacteria) were the first living things. They existed before the evolution of nucleus.

IMAGE OF PROKARYOTE

Eu - means true
Karyote - means nucleus

The next level of organization is eukaryotic cells. Cells with organelles or membrane bound structures. These cells have distinct compartments like nucleus, mitochondria and other organelles that help them carry out their life functions.

Some eukaryotics are unicellular or organisms that are made of one cell. Some eukaryotics are multicellular or organisms that are made of many cells.

IMAGE OF A UNICELLULAR EUKARYOTIC ORGANISM

IMAGES OF MULTICELLULAR EUKARYOTIC ORGANISMS

THE ORDER OF ORGANIZATION FOR MULTICELLULAR ORGANISMS FROM THE LEAST TO THE GREATEST.

FIRST - Organelles are the small organs inside the cell, or the membrane bound structures inside the cell. Ex. nucleus, mitochondria, chloroplast.

SECOND - Cell is the basic unit of life and it is made of organelles.

THIRD - Tissue is a group of the same cells working together to perform one function. Ex. fat tissue, muscle tissue. and nerve tissue,

FOURTH - Organ is a group of different tissues working together to perform one function. Ex. the heart is an organ and it has fat tissue, nerve tissue, and muscle tissue.

FIFTH - Organ system is a group of different organs working together to perform one function. Ex. the digestive system consists of the mouth, the esophagus, the stomach, the large intestine and the small intestine.

SIXTH - Organism is any living thing. All of these structures and systems are coordinated to make a functional organism.

BACK TO TOPICS

Human Impact On The Environment

2010-03-25T10:52:00.000-07:00

Deforestation or Cutting Down Trees

What are some causes of deforestation?
-Clearing land for agriculture or farming

-To build homes, schools, shopping centers

-Harvesting wood for fuel

-To make room for livestocks

What are some consequences of deforestation?

- lost of biodiversity

- extinction

- increase in global warming

- lost of cures for diseases and medicines that control illnesses
-less oxygen

ACID RAIN
Normal rain has a pH of 5-5.6

ACID RAIN is when the pH of rain water is less than 5.

What are the causes of acid rain?

Acid rain is caused by nitrogen oxide and sulfur dioxide released by factories burning fossil fuels ( fossil fuels are fuels made by the remains of dead organisms. Ex. coal, oil, gasoline, cooking gas (methane))

What are some consequences of acid rain?

- damage of soil

- damage to buildings

- damage to plants

- kills animals that live in water (aquatic life)

DAMAGES CAUSE BY ACID RAIN

What biological molecules are affected by pH?
All proteins like: enzymes, hormones and antibodies are affected pH.

How does pH affect the activities of proteins?
Improper pH can change the shape of proteins.

All Proteins have specific shape and this shape is not maintained, the protein may not be functional.

What are some steps that you can take to minimize acid rain?

- vote for politicians who support the environment

- recycling

- start a cyber letter writing campaign

- start an internet site that addresses this problem

What is global warming?

refers to the increase of the average temperature of our planet. This problem is caused by excess carbon dioxide that is released in the environment by burning fossil fuels.

Normally, when the sun ray hits the earth, it is reflected back into space. However, excess carbon dioxide in the atmosphere acts as an insulator and traps the sun rays and thereby preventing it from reflecting back into space. As a result, the average temperature of the earth goes up.

What are some consequences of global warming?

- irregular weather patterns (severe droughts, floods, stronger hurricanes)

- increases the rate of extinction
- melting of ice caps

- loss of drinking water

DAMAGES CAUSE BY GLOBAL WARMING

What are some steps that you can take to reduce global warming?

- recycle

- take public transportation

- tune up your cars

- start a cyber letter writing campaign

- vote for politicians who support the environment

- plant more trees

- educate others about global warming

Increased Human population causes:

- increased pollution

- loss of habitat that leads to higher rate of extinction

- loss of biodiversity (possible loss of medicines and cures for diseases)

- increased global warming

Using Nuclear Power Plants

Advantages

- low carbon dioxide emissions

- the technology is readily available

- it is possible to generate high amounts of electricity within one single planet.

Disadvantages

- always a chance for accidents

- problem with waste disposal

- nuclear power plants can be targets for terrorist attacks

- waste product can be used for the production of nuclear weapons.

Questions

How can spraying pesticide on plants affect aquatic life on near by lakes?

The pesticide can be carried to nearby lakes by rain water.

How can the introduction of new species change an ecosystem?

The new species can bring diseases
May not have any predator in the new ecosystem
Can be a predator to native species

What is it that government can do to prevent the introduction of new species into an ecosystem?

Government can pass laws preventing the introduction of new species into an ecosystem.

What is ecological succession?

Ecological succession is the orderly replacement of organisms in an ecosystem.

List some environmental factors that are carcinogenic or cause cancer.

Some environmental factors that cause cancer are: ultra violet light or sun ray nuclear radiation and cigarette smoking

BACK TO TOPICS

NYS REGENT DIFFUSION LAB

2010-03-18T09:15:00.000-07:00

The word transport refers to how things are taken from one place and carry to another. In the diffusion lab, you will observe how cells can take in materials from the environment and also release materials to the environment based on concentration differences without the use of energy or ATP.

Diffusion is defined as the movement of molecules from an area of high concentration to an area of low concentration and it requires no energy.

DIFFUSION LAB IN A NUTSHELL

Part 1: In class we tested the permeability of a plastic bag (ARTIFICIAL CELL) filled with water, glucose, and starch. In this context, permeability refers to the ability of the plastic bag to allow some substances to go through it while preventing others from doing that.

First, we placed a bag filled with starch solution and glucose in a beaker containing water and iodine (Iodine is a STARCH INDICATOR). An indicator is a chemical that changes color when it comes in contact with certain substances. When starch comes in contact with iodine, it turns black.

See below.

Initial State

RESULTS: Below is the appearance of the cell a few hours later....

If the iodine diffuses through the membrane (plastic bag) and mixes with the starch solution, then it will turn BLACK!

Final State

Note: The cell membrane is selectively permeable. That is, it has holes in it. It is the size of the holes that determines what goes in and out of the cell.

Note: When starch comes in contact with iodine it turns BLACK. Iodine is a starch indicator.

Ask yourself...

Why did the content of the artificial cell or the plastic bag turned black?

The iodine molecules diffused into the artificial cell and turned black when it came in contact with starch.

How come the iodine solution in the beaker did not turn black?

The starch molecules are too large and could not diffuse out of the artificial cell or the plastic bag.

Identify the process.

The process is diffusion. (NOTE: There was a high concentration of iodine in the beaker and low concentration of iodine inside the plastic bag so the iodine moved from high concentration (in the beaker) to low concentration. (in the plastic bag)

"How would the result be different if the iodine was placed in the bag and the starch and the glucose were placed in the beaker?"
(Drawing the scenario might make it easier to answer the question)

Some substances that diffuse freely across the membrane are oxygen, carbon dioxide and water.

Part 2 OSMOSIS in Red Onion Cells:

OSMOSIS is the diffusion of water through a cell membrane. When water goes through the cell membrane, no matter what direction, in or out, it is called "osmosis".

In class we observed osmosis in plant cell by:

FIRST putting a drop of water on a slide.
Putting a piece of red onion tissue (the outer skin) on top of the water.
Placing a cover slip on top of the tissue and press firmly.

When viewed under high power in the microscope, this is what it looks like!

Then to demonstrate osmosis we:

Put a drop of salt water on one side of the cover slip
Place a piece of paper towel on the other side of the cover slip.

This is how the cells looked after the cells exposure to salt water. Water diffused out of the cell

In another example of Osmosis we reversed the process by:

Putting a drop of fresh water on one side of the cover slip.
Placing a piece of paper towel on the other side of the cover slip.

Below is a picture after the water diffused back into the cell.

Observing Osmosis in Elodea

With Fresh Water

Magnified 400 X

With Salt Water

Magnified 1000 X

Osmosis in White Onions

Fresh water

400 X

With Salt water

400 X

Vocabulary
Homeostasis: is defined as a series of processes that help maintain an organisms stable internal environment.

Diffusion: is the movement of particles from an area of greater concentration to an area of lesser concentration and it requires no energy. During diffusion, particles continue to spread until they are evenly distributed.

Osmosis: is the diffusion of water through a cell membrane.

QUICK REVIEW!

NOTE: The cell membrane also controls what goes in and out of the cell by active transport, using special transport proteins.

Active Transport is the movement of particles from an area of low concentration to an area of high concentration and it requires energy (ATP).

ANIMATION OF ACTIVE TRANSPORT

Let us review to other cellular processes, photosynthesis and cell respiration.

"An easy way to remember the formula for photosynthesis and cell respiration"

-What do plants need? (Plants need water, carbon dioxide and light)
-What do plants make? (Glucose and oxygen)

THE FORMULA FOR PHOTOSYNTHESIS
Photosynthesis: Water + CO2 + LIGHT change to glucose + O2 (photosynthesis takes place inside the chloroplast)

TO OBTAIN THE FORMULA FOR CELL RESPIRATION
-Reverse the formula FOR PHOTOSYNTHESIS and replace light with ATP

Cell Respiration: glucose + O2 change to H2O +CO2 +ATP (cell respiration takes place inside the mitochondria)

ALL CHEMICAL REACTIONS THAT TAKE PLACE IN THE BODY REQUIRES THE ASSISTANCE OF ENZYMES.

-Enzymes are biological catalyst that speed up the rate of chemical reactions without becoming part of the final product. -Enzymes have specific shape. They must fit the substrate. Each chemical reaction that takes place in the body requires a different enzyme.

-The immune system helps maintain homeostasis by attacking pathogens and other antigens that found their way into the body.

-The endocrine system helps maintain homeostasis through the action of hormones.

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SCIENTIFIC METHOD

2010-01-19T10:21:00.000-08:00

Designing an experiment

If someone says that they are going to experiment on you, right away you know that they are going to use you as a guinea pig. They are going to do something to you. You are part of the experimental group. However, in order for them to know if what they are doing to you really works, they need to compare you to someone whom they did not experiment on. This person would be the control group.

An experiment always consists of an experimental group and a control group.

The experimental group is the group receiving the treatment, or the group that something is being done to.

The control group does not receive the treatment. The control group is the standard for comparison. The control group is not experimented on.

When you are asked to design an experiment, you should write down the questions that you are trying to answer. That is the problem.

Your hypothesis is what you believe is going to happen and this statement should be generated based on some previous experience or research on this topic. The hypothesis should be carefully written to answer the questions. For example, what is the effect of increasing physical activities on pulse rate? HYPOTHESIS If you increase your physical activities, then pulse rate will increase.

NOTE: A well written hypothesis always consist of the independent and the dependent variable.

Dependent variable is what is being observed or measured. In this case, the dependent variable is the pulse rate.

The independent variable is the treatment or the only factor in an experiment that is manipulated or changed. In this case, the independent variable is increasing physical activities.

ANOTHER WAY OF LOOKING AT THINGS is cause and effect. The independent variable is the cause and the dependent variable is the effect.

NOTE The dependent variable depends on the independent variable. The independent variable you know before the experiment and the dependent variable you find out after the experiment.

OBSERVATION: Probably is the most important step in the scientific method. We observe using our five senses. (Sight, taste, smell, touch and hear).

The experiment is a test of the hypothesis.

Data is information. We collect information or data while we are doing the experiment.

We analyze data after the experiment by looking for patterns using graphs, tables and charts,

Conclusion is an explanation of the data. (after the experiment)

Inference: A conclusion based on observation or evidence.

Theory is a hypothesis that is supported by many experiments or a broad explanation of natural events that is supported by strong evidence of repeated experiments.

Characteristics of a good experiment

In an experiment, the sample size should large (test many subjects) to make up for genetic differences of other inconsistencies.
Can be repeated by anyone and get the same results.
Test only one variable.
Does not have to agree with the hypothesis.

Sample Problem
An experiment was carried out using ten plants of the same species. Growth hormones were added to the soil for the purpose of making the plants grow taller.

State the hypothesis.

Adding growth hormones to plant soil will make plants grow taller.

How will the control group be treated different from the experimental group?

The control group will not receive any hormones and the experimental group will.

Identify the independent variable.

The growth hormones

Identify the dependent variable.

Plant height

List two conditions that must be kept constant

Same amount of water and same amount of sun

What can be done to make the result more meaningful?

Use more plants
Repeat the experiment
Use different species of plants

What type of result would support your hypothesis?

If the plants in the experimental group grow taller than the control group, my hypothesis is supported.

INQUIRY QUIZ VIDEO

MEASURING TEMPERATURE VIDEO

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INQUIRY 2 SCIENTIFIC METHOD

2010-01-19T04:54:00.000-08:00

Designing a Controlled Experiment

When scientists want to find out why something happens the way it does, they conduct an experiment. Since they want the results of the experiment to be taken seriously by other scientists, they use a universal approach to solving problems called the scientific method.

The Scientific Method

Scientist generally follow three steps when they use the scientific method. First, they pose the question that they want to answer. Next, they form a hypothesis, their explanation or guess as to what the answer will be. Then they design and conduct an experiment that will either prove or disprove their hypothesis.

Step 1: Define the Problem

Begin by posing your question very carefully and specifically so you can carry out a proper investigation. If you do not have a good background of the problem, conduct a thorough research of all relevant information available to you, including books, journals, internet...

Step 2: Formulate a Hypothesis

Your hypothesis should be formulated in such a way that it answers the question that you are about to research. For example, if the question is "What is the effect of light intensity on plant growth?", then the hypothesis can be "If light intensity is increased, then plant growth will increase".

Step 3: Design and Conduct a Controlled Experiment

In order to find out whether your hypothesis is true or false, you must test it by conducting a controlled experiment. A controlled actually consist of two experiments run side by side. One is called the control group and the other is called the experimental group. The original experiment is called the control group. The second experiment duplicates the first, except for a single factor called the experimental variable, which you purposely change. If you make sure that only one factor differs between the two experiments, you can be confident that any difference in the results is due to this experimental variable.

Lets Practice Designing a Controlled Experiment

Suppose you want test the effect of light intensity on plant growth. You want to conduct a controlled experiment to find out whether your hypothesis is true or false, so you raise two sets of plants.

Write down anything else beside light intensity that influences plant growth and make sure that these factors remain the same in both groups of plants. For example, the amount of water, the type of soil, the amount of soil, the size of the pot, the temperature are factors that can contribute to plant growth. All these factors must be the same in both groups. The only thing that can be changed in the test group is the light intensity, which is also referred to as the independent variable.

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DNA/GENETICS/PROTEIN SYNTHESIS

2009-12-08T04:11:00.000-08:00

GENETICS
IS THE STUDY OF HOW TRAITS ARE PASSED ON.

HEREDITY
IS THE PASSING OF TRAITS FROM PARENTS TO OFFSPRING OR BABIES.

DNA - What is it?- (Deoxyribonucleic acid) is the master molecule that contains all the information about the organism's traits and it is found in the nucleus.
- Your traits are your proteins
- The information found on your DNA is used to make your proteins or your traits.
Traits - WHAT ARE THEY?

- your characteristics, for example your eye color, your height, the shape of your nose… Note: Most of your traits are not visible.

DNA - How is it made?
- DNA is made by linking smaller molecules called nucleotides.
DNA - What does it look like?
- is described as a double helix or twisted ladder.
- DNA is a polymer. A polymer is a large molecule that is made by linking smaller molecules.- (Examples of other biological polymers are: starch is made by linking glucose, protein is made by linking amino acids.)

DNA model

Nucleotides
- Each nucleotide is made up of a phosphate, a sugar (deoxyribose) and a base.
- It is the bases that hold together the two strands of DNA using weak hydrogen bonds.- There are four bases in DNA adenine, thymine, guanine and cytosine.
- Adenine is paired with thymine and guanine is paired with cytosine.
( A---T, G----C)

CHECK OUT THIS ILLUSTRATION OF A DOUBLE STRANDED DNA!

DNA - What is it made up of?
- The DNA is not one continuous molecule.
- It is made of pieces called chromosomes, and each chromosome has thousands of genes.

CHROMOSOME - WHAT IS IT?
- is one molecule of DNA, usually contains thousands of genes and proteins.

GENE - What is it?is a segment or piece of your DNA or your chromosome that is responsible for one of your traits. For example, you have the gene for eye color, the gene for heights.

It is estimated that the average person has about 50 to 100,000 genes!

CHECK OUT THE RELATION BETWEEN GENES AND CHROMOSOMES
GENES ARE FOUND ON THE CHROMOSOMES AND CHROMOSOMES ARE FOUND INSIDE THE NUCLEUS.

Sexually reproducing organisms

- Have a pair of chromosomes that contain genes for the same traits.

- One chromosome received from the mother and the other chromosome from the father.

- On each of your chromosomes, you have two genes for each of your traits.

REMEMBER: at interphase during the cell cycle, before (cell division) mitosis or meiosis, DNA replication occurs or the DNA copies itself.
- This event is very important in order for the CELL to have a new set of chromosomes for the new cell(s).

During DNA replication

- an enzyme breaks the hydrogen bonds between the nitrogen bases that hold the the two strands together, thus opens up the DNA molecule.

- Each side of the DNA molecule serves as a template or pattern for copying a new strand.

Let us check out this event. BUILD A DNA MOLECULE. Click the link below!!

"INTERACTIVE DNA REPLICATION 1"

CHECK OUT THIS ANIMATION

"DNA REPLICATION" (advance)

How is DNA replication initiated?

- DNA replication begins when an enzyme opens the DNA and each of the old strands is used as a template or a pattern to copy a new strand. (A----T, G----C) Replication is necessary during interphase before the cell undergo mitosis or meiosis when the cell is replicating.

Question: If information on the DNA is information on how to make your proteins, how does this information get to the protein factory or the ribosome?

Answer: This information is sent through a mRNA.

mRNA - What is it?

- The DNA makes a copy of the gene that it wants to express and this copy is called mRNA. It is the mRNA that leaves the nucleus and carries the genetic information to the ribosome for protein synthesis.

AMAZING!!! This DNA is making an RNA copy of one of its genes. (transcription)

Check this out!

The RNA has three bases in common with the DNA. Like DNA, RNA has A (adenine), G (guanine) and C (cytosine. However, the RNA does not have T (thymine), instead it has U (uracil).
DNA has deoxyribose as sugar and RNA has ribose.
DNA is double stranded and RNA is single stranded.

A FEW QUESTIONS ABOUT WHAT YOU'VE LEARNED.....
What is a mutation?

A mutation is any change in the DNA.

Are all mutations bad?

Most mutations are deadly. However, some mutations can help the organism survive changes in the environment.
According to the theory of evolution, the diversity of living things that exist today is the result of mutations and sexual reproduction.

What happens to the information on the DNA?

The information on the DNA is used to make the organism's proteins

How does the DNA get the information for protein synthesis to the protein factory or the ribosome?

The DNA makes a mRNA copy of a gene it wants to express and send this copy to the protein factory, the ribosome. (Although the DNA has the information on how to make all of your proteins, it is not making them all at the same time. The DNA is very conservative; it only makes what it needs when it needs it.)

Why doesn't the DNA itself carry the message to the protein factory or the ribosome?

The DNA contains thousands of genes it is much too big to fit through the pores or the holes of the nuclear membrane.
If the DNA migrates or moves to the cytoplasm, it can be attacked by special enzymes called nucleases.
Additionally, if the mRNA gets damaged, the master copy, the DNA simply makes another mRNA.

Most of the time, the cell is not replicating or copying its DNA. It is expressing its genes or making its genes' products. That is, the information on the DNA is being converted into proteins.

DNA to RNA to Proteins- Transcription is the copying of a DNA into mRNA and this takes place in the nucleus.- Note: RNA does not have the base thymine instead it has uracil. This is the order of the base pairing. (A------U, G------C) The RNA has ribose as sugar and is single stranded.

- Translation is converting the mRNA into an amino acid sequence or protein and this takes place at the ribosome.

- Every three bases or letters represents a CODON. Each codon codes for or represents particular amino acid. For example, UUU codes for the amino acid PHE

- Information on the DNA is information on how to make your proteins.

- Example of proteins are: enzymes, antibodies and hormones."INTERACTIVE PROTEIN SYNTHESIS"

Remember: All proteins have specific shape. An enzyme that breaks down starch will not be able to break down protein because they have different shape. An antibody against the measles will not fight chicken pox because they have different shape. The sex hormone testosterone will not interact with the receptor for the hormone insulin because they have different shape.Traits - WHAT ARE THEY?

- your characteristics, for example your eye color, your height, the shape of your nose…

- However, the expression of your traits can be modified by environmental conditions.

- EXAMPLE: two identical twins one grows up in America and the other grows up in Jamaica. With little knowledge in genetics, it is very easy to infer that these twins will not look identical. The one who grows up in Jamaica will be darker because of the sun and may be shorter and slimmer because of availability and types of food. While the one in the US will be lighter because of less exposure to the sun and may be taller and chunky because food in the states have growth hormones.
Questions:

What is DNA?

DNA is the master molecule that has all of the information about the organism's traits.

How are the bases paired in DNA?

A___T, G____C

Where do you find DNA inside the cell?

DNA is found in the nucleus.

Why is necessary for the DNA to make a RNA copy?

The DNA is too big and it cannot fit though the pores or the holes of the nuclear membrane and also this is done to prevent the DNA from being attacked by nucleases or enzymes that break down DNA.

What is the relation between genes and chromosomes?

On each chromosome, there are thousands of genes. A gene is a piece of your chromosome that codes for one of your traits.

How are the bases paired in RNA?

A___U, G____C

Explain transcription.

Transcription is the process where the DNA is being copied into RNA. This event takes place inside the nucleus.

Explain translation.

Translation is when the mRNA is being converted to an amino acid sequence or protein. This event takes place at the ribosome.

Explain differentiation.

Differentiation is when your cells become specialized. For example, your bone cells and your skin cells they both have the same DNA. However, they each focus on different genes and this allows them to become different cells.

Who do we get our genes from?

We get our genes from our parents.

List three differences between DNA and RNA.

DNA is double stranded and RNA is single stranded.
DNA has thymine as a base and RNA has uracil.
DNA has deoxyribose as a sugar and RNA has ribose.

REMEMBER Information in the DNA is information on how to make your proteins. Any
change in the DNA can lead to a change in the protein.

LET US TAKE A SLIGHT DETOUR.
-Restriction Enzymes are bacteria enzymes that are used to cut double stranded DNA at specific locations called restriction sites. The locations of restriction sites on the chromosomes are not the same for everybody. However, since we inherit our chromosomes from our parents, we also inherit our restriction sites from our parents.

Restriction enzymes are the cutting tools in genetics!What does that mean?
-If the same restriction enzyme is used to cut your DNA and your parents DNA, the size of the pieces that are generated or made will be the same or similar.

How does this information help anybody?
-This information is used to help determine relationship. It is used to determine paternity. (Who’s the baby's daddy?) It is also used in crime scene investigation. It is commonly known as the DNA test.

This is how it works.
-DNA samples are collected from both the father and the baby. Both samples are treated with the same restriction enzymes. Then they are placed in a special apparatus (machine) called gel electrophoresis, which separates the pieces of DNA based on their size and create visual pattern. If this is the father of the baby, the patterns that are created by the baby's DNA and the father's DNA will be similar.

Gel Electrophoresis separates molecules based on their sizes.

Want to learn more?

Check out this link!

"RESTRICTION ENZYMES/GEL ELECTROPHORESIS"

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IMPROVING YOUR TEST SCORES

2009-05-11T09:57:00.000-07:00

Multiple Choice Test Taking Tips

Tips on answering multiple choice questions

Read the question before you look at the answer.

Come up with the answer in your head before looking at the possible answers, this way the choices given on the test won't throw you off or trick you.

Eliminate answers you know aren't right.

Read all the choices before choosing your answer.

If there is no guessing penalty, always take an educated guess and select an answer.

Don't keep on changing your answer, usually your first choice is the right one, unless you misread the question.

In "All of the above" and "None of the above" choices, if you are certain one of the statements is true don't choose "None of the above" or one of the statements are false don't choose "All of the above".

In a question with an "All of the above" choice, if you see that at least two correct statements, then "All of the above" is probably the answer.

A positive choice is more likely to be true than a negative one.

Usually the correct answer is the choice with the most information.

CLASSIFICATION

2009-02-16T02:33:00.000-08:00

TAXONOMY

Taxonomy is the practice and science of classification, the practice of arranging living things in order.

Modern taxonomy is divided into five major categories called kingdoms. These kindoms are further branched into subcategories based on the organisms' structures.

THE MAJOR TAXONOMIC LEVELS ARE:

-Kingdom
-Phylum
-Class
-Order
-Family
-Genus
-Species

The classifications levels become more specific toward the bottom. Many organisms belong to the same kingdom, fewer belong to the same species.

INTERACTIVE CLASSIFICATION

INTERACTIVE CLASSIFICATION2

INTERACTIVE CLASIFICATION3

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REDUCING TEST TAKING ANXIETY

2008-05-11T11:44:00.000-07:00

Reducing Test Taking Anxiety

Test anxiety is when a student excessively worries about doing well on a test. This can become a major hindrance on test performance and cause extreme nervousness and memory lapses among other symptoms. The following are tips on reducing test taking anxiety.

Being well prepared for the test is the best way to reduce test taking anxiety.

Space out your studying over a few days or weeks and continually review class material. Don't try to learn everything the night before.

Try to maintain a positive attitude while preparing for the test and during the test.

Exercising for a few days before the test will help reduce stress.

Get a good night's sleep before the test.

Show up to class early so you won't have to worry about being late.

Stay relaxed, if you begin to get nervous take a few deep breaths slowly to relax yourself and then get back to work.

Read the directions slowly and carefully.

If you don't understand the directions on the test, ask the teacher to explain it to you.

Skim through the test so that you have a good idea how to pace yourself.

Write down important formulas, facts, definitions and/or keywords in the margin first so you won't worry about forgetting them.

Do the simple questions first to help build up your confidence for the harder questions.

Don't worry about how fast other people finish their test; just concentrate on your own test.

If you don't know a question skip it for the time being (come back to it later if you have time), and remember that you don't have to always get every question right to do well on the test.

Focus on the question at hand. Don't let your mind wander on other things.

If you're still experiencing extreme test anxiety after following these tips, seek help from your school counselor.

HUMAN REPRODUCTION

2008-04-15T11:07:00.001-07:00

Male Reproduction System

The purpose of the male reproductive system is to produce and deliver sperms. Sperm is the male gamete or sex cell. Sperm production is influenced by the hormone testosterone. Sperm is produced in the testis. For further explanation.

Click this link: MALE REPRODUCTIVE SYSTEM

Female Reproductive System

The purpose of the female reproductive system is to produce eggs and provide a safe nutritious place for the embryo to develop. Egg maturation and release is influenced by the hormone estrogen, and estrogen is produced by the ovaries. The egg is the female sex cell. For further explanation.

Click this link: FEMALE REPRODUCTIVE SYSTEM

Second Link: REPRODUCTIVE SYSTEM

Third Link: REPRODUCTIVE SYSTEM

HUMAN REPRODUCTION

"CHECK OUT THIS VIDEO ON OVULATION AND FERTILIZATION"

Ovaries- produce eggs.

Ovulation- is the process where the ovary releases the egg.

Fallopian tubes- also known as oviduct is the site of fertilization or is where the sperm meets the egg.

_______________________________________________________
After the sperm enters the egg, the newly formed cell or the zygote travels to the uterus for implantation.
_______________________________________________________

Uterus- is a structure in the female reproductive system that provides a safe nutritious environment for the fetus or the embryo to develop.

Fertilization- is the union of sperm and egg.

Zygote- is a fertilized egg

Placenta- is the site of exchange between the fetus and the mother. For example, nutrients and oxygen go from the mother to the fetus and waste products and CO2 go from the fetus to the mother.

Sexual reproduction requires two parents and the offspring are not identical, except in the case of identical twins.

Asexual reproduction requires only one parent and the offspring are genetically identical to the parent. ( binary fission, fragmentation and budding are other types of asexual reproduction.

How are sex cells different from body cells?

sex cells have half the number of chromosomes, while body cells have a full set of chromosomes.

What type of cell division produce sex cells?

meiosis produces the sex cells or gametes (the sperms or the eggs).

In what structure in the female reproductive system does fertilization occur?

Fertilization occurs in the fallopian tube or oviduct. Fertilization is when the sperm enters the egg.

List two substances that can harm a developing fetus.

Two substances that can harm fetus are drugs and alcohol.

What is the role of the placenta?

the placenta allows material to be exchanged between the fetus and the mother. For example: oxygen goes from the mother to the baby, while carbon dioxide goes from the baby to the mother

To learn more, click this link. HUMAN REPRODUCTION

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Genetic Engineering/DNA technology

2008-04-15T10:32:00.000-07:00

Genetic Engineering involves removing a gene from one organism or living thing and placing it into another organism. This is done so that the organisms with the new gene can make the gene's product. For example, a human insulin gene can be removed from a human chromosome and then inserted or placed into bacteria, and now because the bacteria has the gene for insulin, the bacteria can make insulin. Because bacteria do not use insulin, they pass it out as waste product and humans extract or collect the insulin and use it for people who suffers with diabetes.

Remember, a gene is information on how to make a protein. Once the organism has the gene, it can make the protein.

TRANSGENIC ORGANISMS are organisms with functional foreign genes.

If you place a human gene into bacteria, then the bacteria will make a human protein.

A gene is information on how to make a protein.

Questions and Answers
Identify two molecules that can be made using genetic engineering

Insulin and growth hormone

Identify a group of organisms that benefit from these molecules.

People who are diabetic and youngsters who are not producing growth hormones.

What role does insulin play in the body?

Insulin lowers blood sugar level (It does that by converting glucose into a storage form called glycogen and glycogen is stored in the liver.)

What organ or endocrine gland produces insulin?

Insulin is produced by the pancreas.

Another hormone called glucagon is antagonistic or works to reverse the action of insulin by raising blood sugar level. (Glucagon converts glycogen back into glucose and the glucose is release into the blood.)

Restriction Enzymes are bacteria enzymes that cut double stranded DNA at a specific locations called restriction sites. These restriction sites are found on the non-coding regions of the DNA sometimes referred to as junk DNA . The locations of the restriction sites are different for different individuals. Because we inherit our DNA and therefore our restriction sites from our parents, when using the same restriction enzymes, the cuts are made at similar locations for people who are closely related.

NOTE: In order to remove a human gene from the human chromosome, it is necessary to cut the gene out of the chromosome and this is done using a restriction enzyme.

ADDITIONALLY: In order to place a human gene into bacteria, it is also necessary to cut the bacteria's DNA using the same restriction enzyme that was used to cut the human gene. Another enzyme called ligase is used to join the human gene to the bacteria's DNA.

RESTRICTION ENZYMES are the cutting tools in genetics.

IN FORENSIC ANALYSIS:
In forensic analysis/crime scene investigation, restriction enzymes are used in conjunction or together with another technique called "gel electrophoresis".

Treating DNA with restriction enzymes results in fragments or pieces of different sizes.

GEL ELECTROPHORESIS is method that is used to separate molecules based on their sizes and charges. This technique creates a banding pattern or stains based on the size of the fragments or pieces in the sample used.

GEL ELECTROPHORESIS LAB 1

Gel Electrophoresis Virtual Lab

People who are closely related, their DNA will create similar banding pattern on the gel electrophoresis. This is because the pieces that are generated by the enzyme are of similar sizes.

ONLINE CRIME SCENE INVESTIGATION

OTHER METHODS THAT ARE USED AS MOLECULAR EVIDENCE TO DETERMINE RELATIONSHIP ARE:

Enzyme test

Paper chromatography is a technique used to separate pigment into individual colors.

Amino acid sequence
DNA sequence

Questions

List two ways that we benefit from genetic engineering
What is gel electrophoresis?
In the Biodiversity Lab, what laboratory tools were used in place of restriction enzymes?

What is the purpose of placing a human gene into bacteria?

Answers

We benefit in medicine and in agriculture.
Gel electrophoresis is a technique used to separate molecules by size.
In the biodiversity lab, scissors were used in placed of restriction enzymes.

We place human gene into bacteria so bacteria can make human protein.

List one genetic disease.
• Sickle cell

Identify a technique, which can be used to diagnose this disease
• Gel electrophoresis

List one chromosomal disease.
• Down syndrome

Identify a technique, which can be used to diagnose this disease
• Karyotype

CLICK HERE TO SEE ANIMATION OF KARYOTYPE

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The Systems and Homeostasis

2008-04-15T10:26:00.000-07:00

HOMEOSTASIS is defined as all the processes that help maintain an organism internal environment.

How does the digestive system help in maintaining homeostasis?

The digestive system breaks down food into a form that the cells can use to maintain homeostasis. (Just like in the diffusion lab, the starch was too big and could not go through the artificial membrane. If the food is too big, it will not be able to enter the cell. It will not fit in the holes in the cell membrane)

Digestion begins in the mouth. In the mouth, mechanical digestion starts with the teeth grinding food into smaller pieces. The salivary glands releases saliva, which has a digestive enzyme called amylase. Amylase breaks down starch into smaller pieces and also produce a new substance. Additionally, the saliva moistened the food while the tongue rolls it into a ball. Once the the food is push back to the pharyngeal area, swallowing is initialized automatically.

How would you feel if you were not able to digest your food?

CHECK OUT SOME OF THE ORGANS OF THE DIGESTIVE SYSTEM!

WATCH THIS VIDEO OF THE DIGESTIVE SYSTEM!

ENZYMES AT WORK

ENVIRONMENTAL FACTORS ON ENZYME ACTIVITIES

pH AND ENZYME FUNCTION

How does the respiratory system help in maintaining homeostasis?

- The respiratory system takes in oxygen needed to make ATP and removes carbon dioxide. These activities are necessary in order to maintain homeostasis.

The Human Respiratory System

CHECK THESE VIDEOS ON THE RESPIRATORY SYST. "RESPIRATORY SYSTEM"

How does the circulatory system help in maintaining homeostasis?

- The circulatory system carries oxygen, nutrients and other needed molecules to the cells, while carrying away waste product from the cells.

CHECK THESE VIDEOS ON THE CIRCULATORY SYSTEM: "CIRCULATORY SYSTEM"

How does the immune system help in maintaining homeostasis?

- The immune system is involved in destroying foreign particles and pathogens that would disrupt homeostasis. The immune system kills bacteria and viruses.

How does the endocrine system help in maintaining homeostasis?

- The endocrine system helps maintain homeostasis through the actions of its chemical messengers called hormones. Hormones interact with specific receptors found on cell surfaces or inside the cell. Hormones are produced in specialized cells called endocrine glands and they are released into the blood. The pancreas is an endocrine gland and it produces insulin and glucagon. Insulin lowers blood glucose level by converting glucose into a storage form called glycogen and glycogen is stored in the liver. Glucagon raises blood sugar level by converting glycogen back into glucose.

HORMONES AND RECEPTORS VIDEO

CHECK OUT THIS INTERACTIVE

"CONTROLLING BLOOD SUGAR LEVELS"

Check Out This Video "Endocrine System"

How does the nervous system help to maintain homeostasis?

- The nervous system controls homeostasis using nerve impulses or electrical signals.

How does the excretory system help to maintain homeostasis?

- The excretory system is a series of systems involved in removing waste from the body. For example: the digestive system removes solid waste from the body; the urinary system removes liquid waste from the body; the respiratory system removes carbon dioxide and water from the body; the skin removes nitrogenous waste and other dissolved waste substances.

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IMMNUNE SYSTEM

2008-04-15T10:18:00.000-07:00

The purpose of the immune system is protect the body from pathogens or any foreign particles that can disrupt homeostasis.

What are some ways your body can react when it is invaded by pathogens?
Some possible immune reactions that can occur when your body is invaded by pathogens or foreign particles are:

- produces mucus to trap the pathogens.

- sneezing and coughing to uproot and excrete the pathogens.

- fever to increase blood flow.

- produces white blood cells.

- produces antibodies against invading pathogens.

What are pathogens?

Pathogens are disease causing organisms. Ex. bacteria, viruses.

What are antigens?

Antigens are any foreign particle in the body that triggers an immune reaction.

What are antibodies?

Antibodies are special proteins that are made by your white blood cells to fight infections.

Note: Antibodies are proteins, that is they have specific shape. Antibodies that work against one pathogenic organism will not work against another because of the shape difference.

What are antibiotics?

Antibiotics are drugs that fight pathogens (bacteria, viruses).

What are vaccines?

Vaccinesare a weakened form of a disease used to stimulate the production of antibodies against the disease.

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CELL DIVISION

2008-04-11T11:33:00.000-07:00

Why do cells divide?

Growth
Repair
Old cells die

Mitosis is a cell division that produces two daughter cells that are identical in chromosome number and in combination, for example, a cell with 23 pairs of chromosomes will yield two daughter cells each with 23 pairs of chromosomes and have the same combination.

Cancer is uncontrollable mitosis. The cells continue to divide nonstop and are immortal.

Meiosis is a cell division that produces the gametes or sex cells.
Meiosis reduces the number of chromosomes in half. For example, if a cell has 46 chromosomes and it undergoes meiosis, it will make four daughter cells with 23 chromosomes each. Each of the cells produced by meiosis have a different combination.

When the cell is dividing, if it is producing a sperm or an egg it is meiosis, if not, mitosis.

Meiosis only occurs in the testis and the ovaries.

Fertilization is the union of the sperm and the egg. This union occurs in the fallopian tube

Fertilization restores the chromosome number of the organism.

Meiosis and fertilization are responsible for the variations in species.

Zygote is a fertilized egg.

After the zygote is formed, the cell divides by mitosis and differentiates into the new structures of the organism.

Note: The advantage of sexual reproduction is variation.

Questions

What is mitosis?
How are cell produced by mitosis different from cells produced by meiosis?
Explain fertilization.
Where does fertilization take place?
What is the significance of fertilization?
What are zygotes?

In what structures of the male/female reproductive system does meiosis occur?

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