III. BACKGROUND KNOWLEDGE A. For Teachers

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1 Genetics: The Code of Life Grade Level and Subject: Seventh Grade Science Presented By: Ashlyn Southerland, Miller Core Knowledge Magnet School, Macon, GA Length of Unit: 3 to 4 weeks I. ABSTRACT The answers to the mystery of heredity can be traced easily through the science of genetics. From the beginnings of Gregor Mendel to the fabulous discoveries of Crick and Watson, students are fascinated to uncover the patterns and secret codes illustrated in this unit. These easy to follow lessons are designed to take the headache out of teaching what is often believed to be advanced level material. II. OVERVIEW A. Concept Objectives 1. Develop an awareness of the importance of Gregor Mendel s research. 2. Develop a modern understanding of chromosomes and genes. 3. Appreciate the contributions of modern researchers in genetics. B. Core Knowledge Sequence Content 1. Cell Division C. Skills To Be Taught 1. Describe the process of mitosis and meiosis 2. Outline the events that occur in mitosis and meiosis 3. Describe the structure of a chromosome 4. Understand DNA replication 5. Understand the structure of DNA and RNA 6. Identify the principles of heredity 7. Analyze the findings of early and modern genetic researchers 8. Identify dominant and recessive genes (genotype and phenotype) 9. Predict the results of a genetic cross using a Punnet Square 10. Describe how human traits are determined 11. Summarize common genetic disorders and how they can be inherited 12. Locate examples of modern genetic engineering III. BACKGROUND KNOWLEDGE A. For Teachers B. For Students 1. Core Knowledge Sequence - Grade 5 Cell Structures 2. Core Knowledge Sequence - Grade 5 Cell Processes IV. RESOURCES A. Hopkins, J. (1994) Heredity: The Code of Life, Prentice Hall Science: Englewood Cliffs, NJ. ISBN # B. Laboratory Manual (1993) Heredity: The Code of Life, Prentice Hall Science: Englewood Cliffs, NJ. ISBN # C. Activity Book (1994) Heredity: The Code of Life, Prentice Hall Science: Englewood Cliffs, NJ. ISBN #

2 D. Review and Reinforcement Guide (1993) Heredity: The Code of Life, Prentice Hall Science: Englewood Cliffs, NJ. ISBN # E. Hirsch, E.D. (1994) What Your Seventh Grader Needs to Know, Doubleday Dell: NY. ISBN # V. LESSONS The Beginning Gregor Mendel (10 days) Lesson One: (1 day) 1. Lesson Content: Historical Background of Mendel s research 2. Concept Objective: Develop an awareness of the importance of Gregor Mendel s research. 3. Skill Objectives: Analyze the findings of early genetic researchers and identify dominant and recessive genes (genotype and phenotype) 2. Wall Map of Europe 3. 2 Silk Plants with small flowers 4. Yellow Construction Paper 5. Poster with the 6 Genetic Principles Written Clearly 6. Paper and pencil 7. Pictures of a Persian cat, a Himalayan cat, and a Siamese cat 1. Trait 3. Gene 4. Dominant 5. Recessive 6. Hybrid 7. Incomplete Dominance 8. Phenotype 9. Genotype 1. Begin the unit by asking the students if they have ever been told that they have another relative s features that are different from their parents. Allow some time for story sharing before explaining that the science of genetics determines how traits are inherited. Brainstorm with the students to determine the extent of prior knowledge they have about genetics or heredity. 2. Provide the students with the vocabulary words for defining in their notebook. Discuss each word briefly. 3. Pages of Heredity are excellent summaries of Mendel s work. Remember to locate Austria on the wall map. 4. HOMEWORK: (Due Friday) Using research skills, assign a 1-2 page essay detailing the biographical information and genetic research contributions of one of the following: Rosalind Franklin, James D. Watson, Martha Chase, Jacques Monod, or Barbara McClintock. Papers will be briefly presented individually or grouped by scientist. Encourage students to have visual aids. 1. In class review questions 2. Homework assignment

3 Lesson Two: (1 day) 1. Lesson Content: Historical Background of Mendel s research 2. Concept Objective: Develop an awareness of the importance of Gregor Mendel s research. 3. Skill Objectives: Analyze the findings of early genetic researchers and identify dominant and recessive genes (genotype and phenotype) 2. Wall Map of Europe 3. 2 Silk Plants with small flowers 4. Yellow Construction Paper 5. Poster with the 6 Genetic Principles Written Clearly 8. Paper and pencil 9. Pictures of a Persian cat, a Himalayan cat, and a Siamese cat 1. Trait 3. Gene 4. Dominant 5. Recessive 6. Hybrid 7. Incomplete Dominance 8. Phenotype 9. Genotype 1. Review the biographical info about Mendel and his pea plants. 2. Using the silk plants, demonstrate the concepts of self-pollination and crosspollination. Role-play each by moving appropriately placed bits of yellow construction paper from flower to flower and plant to plant. Discuss natural methods of cross-pollination and how these methods cause growth in new areas. 3. Begin to explain the parent and filial generation discoveries of Mendel. Lead the students through predicting why the shortness (t) trait appeared to disappear to set up the dominant and recessive lesson. 4. HOMEWORK: Continue research 1. In class review questions 2. Homework assignment Lesson Three: (1 day) 1. Lesson Content: Historical Background of Mendel s research 2. Concept Objective: Develop an awareness of the importance of Gregor Mendel s research. 3. Skill Objectives: Analyze the findings of early genetic researchers and identify dominant and recessive genes (genotype and phenotype) 2. Wall Map of Europe 3. 2 Silk Plants with small flowers

4 4. Yellow Construction Paper 5. Poster with the 6 Genetic Principles Written Clearly 6. Paper and pencil 7. Pictures of a Persian cat, a Himalayan cat, and a Siamese cat 1. Trait 3. Gene 4. Dominant 5. Recessive 6. Hybrid 7. Incomplete Dominance 8. Phenotype 9. Genotype 1. Using the pea plant experiments, discuss and illustrate how traits can be dominant or recessive. 2. In class summary questions APPENDIX A. 3. Review answers for understanding. 4. HOMEWORK: Continue research 1. In class review questions 2. Homework assignment Lesson Four: (1 day) 1. Lesson Content: Historical Background of Mendel s research 2. Concept Objective: Develop an awareness of the importance of Gregor Mendel s research. 3. Skill Objectives: Analyze the findings of early genetic researchers and identify dominant and recessive genes (genotype and phenotype) 2. Wall Map of Europe 3. 2 Silk Plants with small flowers 4. Yellow Construction Paper 5. Poster with the 6 Genetic Principles Written Clearly 6. Paper and pencil 7. Pictures of a Persian cat, a Himalayan cat, and a Siamese cat 1. Trait 3. Gene 4. Dominant 5. Recessive 6. Hybrid 7. Incomplete Dominance 8. Phenotype 9. Genotype

5 1. Share the cat pictures around while reading APPENDIX B to the students. Discuss the cross and its results in terms of shared traits and hybrid or purebred breeding. 2. Use the poster of genetic principles to teach them. 3. In class summary questions APPENDIX C. 4. Review answers for understanding. 5. HOMEWORK: Finalize essay for presentation. 1. In class review questions 2. Homework assignment Lesson Five: (1 day) 1. Lesson Content: Historical Background of Mendel s research 2. Concept Objective: Develop an awareness of the importance of Gregor Mendel s research. 3. Skill Objectives: Analyze the findings of early genetic researchers and identify dominant and recessive genes (genotype and phenotype) 2. Wall Map of Europe 3. 2 Silk Plants with small flowers 4. Yellow Construction Paper 5. Poster with the 6 Genetic Principles Written Clearly 6. Paper and pencil 7. Pictures of a Persian cat, a Himalayan cat, and a Siamese cat 1. Trait 3. Gene 4. Dominant 5. Recessive 6. Hybrid 7. Incomplete Dominance 8. Phenotype 9. Genotype 1. Genetic Scientist Essay presentations 1. In class review questions 2. Homework assignment Lesson Six: (1 day) 1. Lesson Content: Historical Background of Mendel s research 2. Concept Objective: Develop an awareness of the importance of Gregor Mendel s research. 3. Skill Objectives: Analyze the findings of early genetic researchers and identify dominant and recessive genes (genotype and phenotype)

6 2. Wall Map of Europe 3. 2 Silk Plants with small flowers 4. Yellow Construction Paper 5. Poster with the 6 Genetic Principles Written Clearly 6. Paper and pencil 7. Pictures of a Persian cat, a Himalayan cat, and a Siamese cat 1. Trait 3. Gene 4. Dominant 5. Recessive 6. Hybrid 7. Incomplete Dominance 8. Phenotype 9. Genotype 1. Introduce the concept of probability by explaining that probability is expressed in fractions or percentages. Ask the students, If a family has 5 daughters, what is the probability that the next child will be a girl? Discuss the 50% probability until the students understand. 2. Use pages to explain and illustrate the use of Punnet squares to determine simple traits in offspring. 3. Have several blank Punnet squares for the children to practice using. 4. HOMEWORK: More fun with Punnet squares (teacher generated) 1. In class review questions 2. Homework assignment Lesson Seven: (1 day) 1. Lesson Content: Historical Background of Mendel s research 2. Concept Objective: Develop an awareness of the importance of Gregor Mendel s research. 3. Skill Objectives: Analyze the findings of early genetic researchers and identify dominant and recessive genes (genotype and phenotype) 2. Wall Map of Europe 3. 2 Silk Plants with small flowers 4. Yellow Construction Paper 5. Poster with the 6 Genetic Principles Written Clearly 6. Paper and pencil 7. Pictures of a Persian cat, a Himalayan cat, and a Siamese cat 1. Trait 3. Gene 4. Dominant

7 5. Recessive 6. Hybrid 7. Incomplete Dominance 8. Phenotype 9. Genotype 1. In class summary questions APPENDIX D 2. Review answers for understanding. 3. Problem Solving Activity p. 27 of Heredity: The Code of Life 4. Complete for Homework 1. In class review questions 2. Homework assignment Lesson Eight: (1 day) 1. Lesson Content: Historical Background of Mendel s research 2. Concept Objective: Develop an awareness of the importance of Gregor Mendel s research. 3. Skill Objectives: Analyze the findings of early genetic researchers and identify dominant and recessive genes (genotype and phenotype) 2. Wall Map of Europe 3. 2 Silk Plants with small flowers 4. Yellow Construction Paper 5. Poster with the 6 Genetic Principles Written Clearly 6. Paper and pencil 7. Pictures of a Persian cat, a Himalayan cat, and a Siamese cat 1. Trait 3. Gene 4. Dominant 5. Recessive 6. Hybrid 7. Incomplete Dominance 8. Phenotype 9. Genotype 1. Prepare students for the test/quiz by allowing them today to complete the sheet called APPENDIX E. 2. Finish for homework 1. In class review questions 2. Homework assignment Lesson Nine: (1 day) 1. Lesson Content: Historical Background of Mendel s research

8 2. Concept Objective: Develop an awareness of the importance of Gregor Mendel s research. 3. Skill Objectives: Analyze the findings of early genetic researchers and identify dominant and recessive genes (genotype and phenotype) 2. Wall Map of Europe 3. 2 Silk Plants with small flowers 4. Yellow Construction Paper 5. Poster with the 6 Genetic Principles Written Clearly 6. Paper and pencil 7. Pictures of a Persian cat, a Himalayan cat, and a Siamese cat 1. Trait 3. Gene 4. Dominant 5. Recessive 6. Hybrid 7. Incomplete Dominance 8. Phenotype 9. Genotype 1. Content review from p. 30 of the text is an excellent summary of the material. 2. Remind the students to study for the test/quiz. 1. In class review questions 2. Homework assignment Lesson Ten: (1 day) 1. Lesson Content: Historical Background of Mendel s research 2. Concept Objective: Develop an awareness of the importance of Gregor Mendel s research. 3. Skill Objectives: Analyze the findings of early genetic researchers and identify dominant and recessive genes (genotype and phenotype) 2. Wall Map of Europe 3. 2 Silk Plants with small flowers 4. Yellow Construction Paper 5. Poster with the 6 Genetic Principles Written Clearly 6. Paper and pencil 7. Pictures of a Persian cat, a Himalayan cat, and a Siamese cat 1. Trait 3. Gene 4. Dominant 5. Recessive 6. Hybrid

9 7. Incomplete Dominance 8. Phenotype 9. Genotype 1. Test/Quiz 1. In class review questions 2. Essay 3. Teacher generated test/quiz The Middle (for there is no end ) Genes and Chromosomes Lesson Eleven: (1 day) 1. Lesson Content: Structure and function of genes, chromosomes, and DNA 2. Concept Objective: Develop a modern understanding of chromosomes and genes. 3. Skill Objectives: a. Describe the structure of a chromosome b. Understand DNA replication c. Understand the structure of DNA 2. Individual squares of paper labeled with the nitrogen base letters 3. Popsicle sticks 4. Paper Towels 5. A lot of 4 different colored gum drops 6. Mini marshmallows 7. Styrofoam Bases 1. Chromosome 2. Deoxyribonucleic Acid 3. Replication 4. Helix 5. Protein 6. Meiosis 7. Mitosis 1. After reviewing the previous material about Mendel and his discoveries, continue using the text Heredity: The Code of Life to explain the Chromosome Theory (genes are carried from parents to offspring on chromosomes) Pages are very helpful. Continue doing Punnet squares with the students to increase their ability. 2. Provide the students with the vocabulary words for defining in their notebook. Discuss each word briefly. 3. HOMEWORK: Ask the students to bring in some clay and yarn for tomorrow s class project. 1. Review questions 2. Replication Activity Participation 3. DNA Molecule Project

10 Lesson Twelve: (1 day) 1. Lesson Content: Structure and function of genes, chromosomes, and DNA 2. Concept Objective: Develop a modern understanding of chromosomes and genes. 3. Skill Objectives: a. Describe the structure of a chromosome b. Understand DNA replication c. Understand the structure of DNA 2. Individual squares of paper labeled with the nitrogen base letters 3. Popsicle sticks 4. Paper Towels 5. A lot of 4 different colored gum drops 6. Mini marshmallows 7. Styrofoam Bases 1. Chromosome 2. Deoxyribonucleic Acid 3. Replication 4. Helix 8. Protein 9. Meiosis 10. Mitosis 1. Using the clay and yarn, ask the students to make a model of the structure of a chromosome. The clay can represent the protein and the yarn can represent the DNA. 2. Have students use their models to describe the structure and function of the chromosome. 3. Collect several of the models to use in a hands on illustration of the process of meiosis (Chromosomes doubling within cells, then dividing into other cells, eventually resulting in the formation of sex cells sperm and egg containing the sex chromosomes X and Y). 4. HOMEWORK: Summary questions APPENDIX F 1. Review questions 2. Replication Activity Participation 3. DNA Molecule Project Lesson Thirteen: (1 day) 1. Lesson Content: Structure and function of genes, chromosomes, and DNA 2. Concept Objective: Develop a modern understanding of chromosomes and genes. 3. Skill Objectives: a. Describe the structure of a chromosome b. Understand DNA replication c. Understand the structure of DNA

11 2. Individual squares of paper labeled with the nitrogen base letters 3. Popsicle sticks 4. Paper Towels 5. A lot of 4 different colored gum drops 6. Mini marshmallows 7. Styrofoam Bases 1. Chromosome 2. Deoxyribonucleic Acid 3. Replication 4. Helix 5. Protein 6. Meiosis 7. Mitosis 1. Review the homework for understanding before beginning to explore the DNA molecule. 2. Treat this part of the lesson as a James Bondian mystery. The DNA is the container of the genetic code; the reason we look and sometimes, as research is discovering, act. Use pages of Heredity: The Code of Life to aid you in your lecture and board illustrations. 3. Explain that the helix (twisted ladder) structure of DNA has phosphate groups and sugar molecules as side supports, while the center rungs are made up of Adenine, which always pairs with Thymine, and Guanine, which always pairs with Cytosine (and vice versa). 4. Ask the students to determine the other strand of the following DNA molecule for practice in class AACGTTT. (Answer: TTGCAAA) 5. HOMEWORK: Make up at least 10 different strands of DNA for the students to figure out the other half. 1. Review questions 2. Replication Activity Participation 3. DNA Molecule Project Lesson Fourteen: (1 day) 1. Lesson Content: Structure and function of genes, chromosomes, and DNA 2. Concept Objective: Develop a modern understanding of chromosomes and genes. 3. Skill Objectives: a. Describe the structure of a chromosome b. Understand DNA replication c. Understand the structure of DNA 2. Individual squares of paper labeled with the nitrogen base letters 3. Popsicle sticks 4. Paper Towels 5. A lot of 4 different colored gum drops

12 6. Mini marshmallows 7. Styrofoam Bases 1. Chromosome 2. Deoxyribonucleic Acid 3. Replication 4. Helix 5. Protein 6. Meiosis 7. Mitosis 1. Check homework. 2. Explain the total process of DNA replication (DNA unzips and free nitrogen bases floating in the nucleus attach to the strand appropriately forming two DNA molecules. 3. To further illustrate replication, figure out ahead of time the number of students necessary to act out the process. The following is the formula for 24 students: 6 students are one strand of a DNA molecule and 6 are the other side (based on nitrogen pairings). Give the DNA molecule students a slip of paper with their nitrogen base code. Ask them to pair up correctly and join hands (or wrists). Check the pairings. The remaining 12 students represent the free nitrogen bases in the nucleus. Give them their appropriate slip of paper and ask them to begin floating around the classroom. Go to the DNA molecule students and walk right up the middle, causing them to drop hands. The right side of the separated molecule should go and line up exactly as they are somewhere else. When this happens, the free nitrogen base students should begin to join up with their partner nitrogen base, thus resulting in 24 students becoming two identical strands of DNA. 4. HOMEWORK: Summary questions APPENDIX G 1. Review questions 2. Replication Activity Participation 3. DNA Molecule Project Lesson Fifteen: (1 day) 1. Lesson Content: Structure and function of genes, chromosomes, and DNA 2. Concept Objective: Develop a modern understanding of chromosomes and genes. 3. Skill Objectives: a. Describe the structure of a chromosome b. Understand DNA replication c. Understand the structure of DNA 2. Individual squares of paper labeled with the nitrogen base letters 3. Popsicle sticks 4. Paper Towels 5. A lot of 4 different colored gum drops 6. Mini marshmallows 7. Styrofoam Bases

13 1. Chromosome 2. Deoxyribonucleic Acid 3. Replication 4. Helix 5. Protein 6. Meiosis 7. Mitosis 1. (You may provide some or all of the materials on your own, but it is preferable to ask the students to secure them individually.) Have each student make up their own DNA molecule with no less than 6 nitrogen bases on one side (any less is too small more than 10 gets too heavy and the model falls). Check their combinations to insure the pairs are matched correctly. Ask them to label the color of gumdrop that represents each nitrogen base in a key. (Example: Red = Adenine, Green = Thymine, Purple = Guanine, Yellow = Cytosine) 2. Pass out paper towels, 2 Popsicle sticks, one Styrofoam base, and a handful or so of mini marshmallows to each student. Ask them to lay their gumdrops out on the paper towel as they intend them to be assembled. When they are done, tell them to assemble their project by securing the Popsicle sticks in to base, use the mini marshmallows as anchors and representatives of the phosphate groups and sugar molecules down the sides, and use the gumdrops as the nitrogen bases in the middle. 3. They usually want to eat their creation (gross hands and all) so evaluate the project as it progresses. You know your students. 1. Review questions 2. Replication Activity Participation 3. DNA Molecule Project 4. Teacher generated test/quiz VI. CULMINATING ACTIVITY VII. WORKSHEETS/HANDOUTS See attached Appendices A, B, C, D, E, F, G, VIII. BIBLIOGRAPHY See Resources

14 APPENDIX A: Genetics: The Code of Life 1. What is genetics? 2. What organisms did Gregor Mendel study? 3. What is a dominant trait? 4. What is a recessive trait? 5. How are dominant traits represented in the genetic code? 6. How are recessive traits represented in the genetic code? 7. Explain why recessive traits seem to disappear and then reappear in future generations. 8. What do we call the process of pollen from the flower of one plant falling on the pistil of a flower on the same plant? 9. Explain cross-pollination. 10. What genetic scientist are you researching?

15 APPENDIX B: Genetics: The Code of Life Breeding the Purr-fect Cat Did you know that cats are now more popular than dogs as pets in the United States? Many people adopt homeless cats from animal shelters, and others prefer to buy purebred cats from cat breeders. Two of the most popular kinds of purebred cats are Siamese cats and Persian cats. Both of these breeds are very old. Siamese cats have long, thin bodies. They are short-haired, with dark markings on the face, feet, and tail. Persian cats are longhaired, with short, stocky bodies. In the 1930 s, these two breeds were combined in a series of genetics experiments carried out by scientists at Harvard Medical School. The scientists were trying to find out how certain traits in cats are inherited. The result of their work was a new, artificial breed of cat called the Himalayan. The first Himalayan cat was born in The kitten had long hair like a Persian and the markings of a Siamese. After the birth of the first Himalayan kitten, professional cat breeders took over. In the 1960 s, Himalayans were recognized by groups, such as the Cat Fanciers Association (CFA), that sponsor major cat shows in the United States. Owners of Himalayan cats can thank Gregor Mendel for their pets. Without the science of genetics, these beautiful cats might never have existed. Can you think of any other crosses in the animal kingdom?

16 APPENDIX C: Genetics: The Code of Life 1. List the six basic principles of genetics. 2. What is a hybrid organism? 3. What is a purebred organism? 4. Explain why a short-stemmed pea plant can never be hybrid. 5. Which stem length is dominant in pea plants? 6. Why do organisms resemble their parents and other relatives? (paragraph answer)

17 APPENDIX D: Genetics: The Code of Life 1. What is probability? 2. What is a phenotype? 3. What is a genotype? 4. How can two organisms have the same phenotype (for example: black), but different genotypes (for example: BB and Bb)? 5. List 3 examples of any phenotype. 6. List 3 examples of any genotype. 7. Use a Punnet square to predict the outcome of a cross between a hybrid black (Bb) guinea pig and a white (bb) guinea pig. 8. From your Punnet square, what are all of the possible genotypes for the offspring? 9. From your Punnet square, what are all of the possible phenotypes for the offspring? 10. Use a Punnet square to predict the outcome of a cross between a hybrid black (Bb) guinea pig and another hybrid black (Bb) guinea pig. 11. From your Punnet square, what are all of the possible genotypes for the offspring? 12. From your Punnet square, what are all of the possible phenotypes for the offspring? 13. A family has four daughters. What is the probability that a fifth child will be a girl? Does the fact that there are already four daughters in the family increase the probability of having another girl? Use a law of genetics to explain.

18 APPENDIX E: Genetics: The Code of Life 1. Create a Punnet square for the following cross: A hybrid black rabbit (Bb) and a purebred brown rabbit (bb). (Bb, Bb, bb, bb) 2. In pea plants, short stems (t) are recessive and tall stems (T) are dominant. Two hybrid pea plants (Tt x Tt) are crossed. One hundred seeds from the two plants are collected and planted. How many plants in the next generation would you expect to have tall stems? (75) 3. Imagine that you are a student in the 1860 s visiting Gregor Mendel in his garden. Write a personal letter to a friend describing Mendel s experiments with pea plants.

19 APPENDIX F: Genetics: The Code of Life 1. State the chromosome theory of heredity. 2. What is mitosis? 3. What is meiosis? 4. Explain the process of meiosis in detail. 5. Why are the X and Y chromosomes called the sex chromosomes? 6. What are the sex cells for male and female? 7. How does the process of meiosis explain Mendel s law of segregation? 8. Humans have 46 chromosomes in their body cells. How many pairs are in these same cells? 9. Explain how the male in most species determines the gender of the offspring. 10. Where are chromosomes found in a cell? 11. Specifically, where are genes found in a cell?

20 APPENDIX G: Genetics: The Code of Life 1. What is the job of DNA in heredity? 2. Specifically, where can DNA be found in a cell? 3. Fully describe the structure of DNA. (Include the sides, middle, and shape) 4. What is replication? 5. List the steps in the process of DNA replication. 6. The nitrogen bases on one strand of a DNA molecule are in the following order: AGTTCTCCAGCG. What is the order of the nitrogen bases on the other half of the molecule?