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GeneticsGenetics

  • Subject:
  • |
  • Grade(s): 6-8
  • |
  • Duration: Two class periods

Lesson Plan Sections

Objectives


Students will understand the following:
1. Many human characteristics—all physical traits and possibly many personality traits—are determined by our genetic makeup.
2. Whereas all physical traits are genetically determined, some evidence shows that certain personality traits are determined by conditions and events that occur after a person's birth.
3. Because of their identical genetic makeup, identical twins who have been raised separately are ideal subjects for experiments that evaluate the effects of genes versus the effects of environment on human personality development.

Materials


No special materials needed

Procedures


1. Begin a conversation with your students by asking, "Which is a more important factor in how your personality develops—nature or nurture?" Explain that by nature you mean hereditary genetic makeup and that by nurture you mean the things that happen to a person after birth, including treatment by parents, peers, community, and society. Let students know that another name for the nature-nurture controversy is the heredity-versus-environment controversy. Then encourage students to express their views on the issue and give reasons for their views.
2. Ask students if they can think of a way to construct an experiment, in a scientifically valid way, that will shed light on the controversy they have been discussing. Guide the discussion toward twin studies, or the study of pairs of identical twins that have been raised apart.
3. Ask students to explain why identical twins raised apart would be ideal subjects for an experiment. Make sure students understand that identical twins have exactly the same genetic makeup, so any inherited traits, including all physical traits, would be exactly the same, but if raised separately, the twins would grow up with different environmental influences.
4. Divide the class into groups, and assign each group to come up with a design for an experiment that would cast light on the nature-nurture controversy. All experimental designs should involve a pair of twins raised apart from each other.
5. Before groups meet, go over the scientific method with the class, explaining to students the requirements for a scientifically valid experiment:
  1. The experiment should begin with a question to be answered (e.g., "Is musical ability determined by nature or nurture?").
  2. The experimenters should form a hypothesis, or educated guess, based on knowledge and/or experience (e.g., "Musical ability is determined by nature.").
  3. The experiment should be set up so that there is only one variable; that is, all conditions must be the same except for the one the experiment is designed to test. (In the case of twins, we know that each twin has the exact same genetic makeup, or "nature"; therefore, the only variable is environment, or "nurture.")
  4. The experiment should have a control. (In the case of a twin study, the "experiment" might be a musically talented twin who was raised by musically talented parents; the "control" might be the other twin, raised by parents who are not musically talented.)
You should also mention to the class that the results of just one experiment are rarely considered sufficient. An experiment must be repeated many times before the results can be taken seriously.
6. Allow time for groups to design their experiments.
7. Have each group present its experimental design to the class.
8. Invite class members to critique each experiment with regard to the validity of its design and use of scientific method.

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Adaptations


Have students research actual twin studies that have been performed.

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Discussion Questions


1. What evidence is presented to indicate that memory is a biological process that can be controlled?
2. Under what circumstances might it be appropriate to manipulate human memory?
3. It is easy to imagine the influence of genes in the expression of traits such as height and weight. Discuss how much genes influence non-biological traits such as habits, gestures and personalities.
4. Explain how your DNA is like that of flies, paramecia or flowers.
5. How do genetic research and our further understanding of DNA bring us closer to solving the "riddle" of life?
6. Debate whether or not genetic research should be regulated. If so, how?

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Evaluation


You can evaluate groups on their experimental designs using the following three-point rubric:

 

  • Three points: meets all the requirements of a scientifically valid experiment; description of experiment clearly written, well organized, and error-free

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  • Two points: meets most of the requirements of a scientifically valid experiment; description of experiment adequately written and organized, with several errors in grammar, usage, and mechanics

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  • One point: lacks a question and/or a hypothesis; description poorly written, disorganized, with numerous errors

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Extensions


3-D Model
Have groups of students build three-dimensional models of DNA to demonstrate and explain the molecules, structure and mechanism for replication. They will need to work from pictures obtained from research.

Code of Life
Explain to students that a code is a system of symbols used to store information. The 26 letters in the English alphabet are symbols that when combined form an unlimited number of words that can be used to store written information. Explain further that DNA is a type of code. The DNA alphabet consists of only four letters (A, C, T, and G) which stand for the four nucleotides that make up the DNA molecule. "DNAese" is made up of three-letter "words" to code for the 20 amino acids that are used to construct the structural and functional proteins in the cell. Challenge your students to create their own dictionary of three-letter code words using only the letters A, C, T, and G. Then they can send coded messages to friends.

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Suggested Readings


The Thread of Life
Susan Aldridge, Cambridge University Press, 1996
For the serious student, a full exploration of DNA and its manipulation to address new life forms, altered plants, and environmental solutions.

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Links


The Gene Letter
For geneticists' thoughts on whether or not Jurassic Park is possible or cloning humans is ethical, see these essays. "The Gene Letter" is a product of The Shriver Center, which was awarded a U.S. Department of Energy grant to create an electronic newsletter about the ethical, legal, and social issues pertaining to genetics and genetic engineering.

The Johann Gregor Mendel Page
Historical information about the beginnings of genetics and biographical information on the founder of modern genetics, Gregor Mendel.

The Bioethics Internet Project
Help your students prepare for the ethical challenges of their genetically engineered futures.

Welcome to Morgan: A Genetics Tutorial
A multimedia tutorial that covers the basic principles of genetics suitable for a high school biology class.

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Vocabulary


Click on any of the vocabulary words below to hear them pronounced and used in a sentence.
speaker    gene
Definition: A specific sequence of nucleotides in DNA or RNA that is located in the germ plasm usually on a chromosome and that is the functional unit of inheritance controlling the transmission and expression of one or more traits.
Context: The gene that can give a fly photographic memory may one day provide a therapy for Alzheimer's disease.
speaker    genetic
Definition: Relating to or determined by the origin, development, or causal antecedents of something.
Context: The same basic genetic program has been used over and over again.
speaker    homeosis
Definition: Relating to a gene producing a major shift in structural development in which one part of the body is replaced with another.
Context: He named these transformations homeosis, a replacement of one part of the body with another.
speaker    identical twins
Definition: Two persons closely resembling each other who were produced from the same fertilized egg.
Context: Identical twins are produced from a single fertilized egg.
speaker    genetic engineering
Definition: The directed alteration of genetic material by intervention in genetic processes.
Context: Davis could employ modern genetic engineering.

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Standards


This lesson plan may be used to address the academic standards listed below. These standards are drawn from Content Knowledge: A Compendium of Standards and Benchmarks for K-12 Education: 2nd Edition and have been provided courtesy of theMid-continent Research for Education and Learningin Aurora, Colorado.
 
Grade level: 6-8
Subject area: life science
Standard:
Knows about the diversity and unity that characterize life.
Benchmarks:
Knows that although different species look very different, the unity among organisms becomes apparent from an analysis of internal structures, observation of the similarity of their chemical processes and the evidence of common ancestry.

Grade level: 9-12
Subject area: life science
Standard:
Understands the genetic basis for the transfer of biological characteristics from one generation to the next.
Benchmarks:
Knows that in all organisms, the instructions for specifying the characteristics of the organism are carried in DNA; the chemical and structural properties of DNA explain how the genetic information that underlies heredity is both encoded in genes (as a string of molecular "letters") and replicated (by a templating mechanism).

Grade level: 9-12
Subject area: life science
Standard:
Understands the genetic basis for the transfer of biological characteristics from one generation to the next.
Benchmarks:
Knows that genes are segments of DNA molecules, and that inserting, deleting or substituting portions of the DNA can alter genes; changes in DNA (mutations) can also occur when a cell is exposed to certain kinds of radiation or chemical substances.

Grade level: 9-12
Subject area: life science
Standard:
Knows the general structure and functions of cells in organisms.
Benchmarks:
Knows that cells store and use information to guide their functions; the genetic information stored in DNA is used to direct the synthesis of the thousands of proteins that each cell requires.

Grade level: 9-12
Subject area: life science
Standard:
Understands the basic concepts of the evolution of species.
Benchmarks:
Knows that heritable characteristics, which can be biochemical and anatomical, largely determine what capabilities an organism will have, how it will behave and, hence, how likely it is to survive and reproduce.

Grade level: 9-12
Subject area: technology
Standard:
Understands the scientific enterprise.
Benchmarks:
Knows that scientists in different disciplines ask different questions, use different methods of investigation, and accept different types of evidence to support their explanations; many scientific investigations require the contributions of individuals from different disciplines (including engineering) and new disciplines of science often emerge at the interface of two older disciplines (e.g., geophysics, biochemistry).

Grade level: 9-12
Subject area: technology
Standard:
Understands the interactions of science, technology and society.
Benchmarks:
Knows that individuals and society must decide on proposals involving new research and technologies; decisions involve assessment of alternatives, risks, costs and benefits, and consideration of who benefits and who suffers, who pays and gains and what are the risks and who bears them.

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Credit


Summer Productions, Inc.

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