Materials Included In Kit

Additional Materials Required

Disposal

Items can be reproduced and, with proper care, used many times.

Teacher Tips

• Enough materials are provided for 32 students working individually and in pairs. All materials are reusable.

• Explain the various genetic combinations that are possible and the phenotypes that will result from each combination of alleles from the Bothead Inheritance Sheet.
• For added value and extended use, Gene Card and Mutation Card Sheets may be laminated. For ease in laminating, gene and mutation cards were not cut out.
• Prior to the activity:
  1. Cut apart and separate into individual sets all of the Gene and Mutation Cards for each trait.
  2. Make copies of the Parent Bothead Sketch Sheets (2/page) and cut in half. These will be distributed to each student.
  3. Make enough copies of the larger Baby Bothead Sketch Sheet for each set of “parents.”
  4. Make enough copies of the Bothead Inheritance Sheet for each student.

• Although this activity assumes students are familiar with and understand some basic concepts of genetics, you may need to explain these terms: alleles, meiosis, fertilization, genotype, phenotype, dominant and recessive traits, codominance and mutations.
• This simulation can be extended for additional generations and used to help answer questions, such as:
  1. How do mutations affect a population over time? 
  2. If most mutations are considered “bad” for organisms, how can they remain within a population?

• Although results will vary a great deal due to the randomness of card selection and rolling the die, chances are very good that few, if any, individuals in the 1st generation will look identical.
• Similar activities may be created with 3-D, manipulative objects, such as Legos^® or Mr. Potatohead^®.

Answers to Questions

1. Was the “baby” identical to either “parent”? Use parent genotypes to help explain your answer.

Answers will vary but generally should be, No! The explanation should include something like: …because each “baby” is only receiving one half of each parent’s genes and therefore, will be a mixture of the two parents.

2. Was the “baby” identical to any other “babies” created in the classroom? Why or why not?

Answers will vary but generally should be, No! The explanation should include: ...because each baby had different parents.

3. How many different types of babies were created? (Look carefully!)

Answers will vary depending on the number of students in the class.

4. Did your “baby” have any type of mutation? If yes, describe the mutation and then write a short paragraph to answer these two questions:

1. How do you think this mutation will affect its ability to survive?
2. How do you think this mutation will affect its ability to mate and/or reproduce?

Answers to the first question will vary. The answers to Questions a and b should include their ideas about what Botheads eat, how they detect prey or predators, how they might attract a mate and how changes in the environment might affect their survival.

5. Are Bothead babies clones? Explain your answer.

The answer should be something like: No, because none of the babies are 100% identical to the parents and clones are always identical to the parents.

6. Does phenotype determine genotype or vice versa? Explain your answer.

Genotype determines phenotype because the type of genes an organism has in its DNA determines the physical characteristics of the organism.

7. Based on your and your partner’s results, please answer the question posed in the Introduction: Why do I look different than my parents or my siblings? (Be as specific as possible!)

I do not look 100% like either parent because I did not inherit 100% of either parent’s genes and the mixture of genes I received is different than those received by my siblings.

8. Thought Question: If the majority of children look different than their parents, how are identical twins or even triplets produced?

Twins and triplets are produced when a single fertilized egg cell (the zygote) splits entirely in two or into threes and then each part of the egg develops into separate and distinct individuals. Normally, this separation does not occur and the zygote stays together producing a single individual.

References

Tamarin, R. H. Principles of Genetics; McGraw-Hill: New York, NY; 2002; 7th edition.

Introduction

This activity will illustrate the general principles which cause genetic variation among the offspring of organisms that reproduce sexually. It will also help in answering the problem question: Why do I look different than my parents and my siblings [brother(s) and/or sisters(s)]?

Concepts

• Alleles

• Genotype vs. phenotype
• Dominant vs. recessive
• Mutation

Background

Gregor Mendel (1822–1884) is known as the father of genetics for his work studying the inheritance patterns in garden peas. Genetics studies the transmission, expression and evolution of genes. Genes are molecules that control function, development and appearance of individuals. Mendel is responsible for first discovering the rules of transmission of genes from one generation to another.

Mendel used Pisum sativum, also known as the common pea plant, to study inheritance of characteristics over several generations. Mendel used only homogeneous plants, or true-breeding for a particular trait. He also chose to track plants that only had two alleles—form of a gene, such as tall or dwarf plants. The offspring of the parent generation is known as the F₁ generations. The F₁ generation is known as the hybrid generation because it consisted offspring from different parents. One parent was tall and the other parent was dwarf. All the F₁ plants produced were tall so Mendel realized that tall was a dominant trait. The short plants would be referred to as recessive. Different forms of a gene are known as alleles. Therefore if the height of the plant was represented by the letter H, a capitalized H would represent the dominant allele and a lower case h would represent the recessive allele.

Mendel used this information to develop the Law of Segregation. Simply stated, a gamete receives only one allele from each parent. In order to understand this law it is essential to understand some basic genetic terminology. The genotype of an organism is the gene combination it possesses. For example, when studying height three genotypes are possible—HH, Hh or hh. The phenotype describes the observable features of an organism. Plants with the genotype HH or Hh are both phenotypically tall despite the fact they are different genotypically. Genotypes have two classes homozygotes, in which both alleles are the same, such as HH or hh, and heterozygous, in which the two alleles are different, such as Hh. Therefore HH is homozygous dominant, Hh is heterozygous, and hh is homozygous recessive.

Materials

Safety Precautions

This activity is considered non-hazardous. Follow all laboratory safety guidelines.

Procedure

1. Select a set of 10 Bothead Gene Cards (two of each color), a Parent Bothead Sketch Sheet and a Bothead Inheritance Sheet.
2. Before looking at your cards carefully read the Bothead Inheritance Sheet.
3. Examine your cards and write your Bothead’s genotype on the line labelled Parent Genotype on the Parent Bothead Sketch Sheet. Hint: When writing genotypes, only letters of the same kind are written together with the capitol letter first (e.g., AA or Aa, BB, Bb).
4. Using the Bothead Inheritance Sheet identify the phenotype and then draw your Bothead’s phenotype on the Sketch Sheet.
5. Once finished, pair with another student. Each of your Botheads will represent one parent. Create a baby Bothead according to the following directions.

1. Place all 20 of each parents’ colored Gene Cards face down on a table, counter or desktop with only the label showing (e.g., Decorative Trim Gene Card).
2. Choose a specific Bothead trait, like Sound Sensors, and roll the die. If a six is rolled, get a colored Mutation Card for that trait. Next, randomly turn over two Gene Cards for that trait and set the three cards aside. (If the roll of the die does not produce a six, randomly select 2 Gene Cards for that trait and set them aside.)
3. Repeat steps a and b for the other four Bothead traits.
4. When all five traits have been selected, obtain a large Baby Bothead Sketch Sheet and write your “baby’s” genotype on the line labeled Baby Genotype.
5. Use the Bothead Inheritance Sheet to identify the phenotype and then draw the “baby,” including any mutations, on the sketch sheet.
6. Display your Bothead “baby” in the designated area so that everyone may see it.

6. Items can be reproduced and, with proper care, used many times.

1. Was the “baby” identical to either “parent”? Use parent genotypes to help explain your answer.
2. Was the “baby” identical to any other “babies” created in the classroom? Why or why not?
3. How many different types of babies were created? (Look carefully!)
4. Did your “baby” have any type of mutation? If yes, describe the mutation and then write a short paragraph to answer these two questions:

1. How do you think this mutation will affect its ability to survive?
2. How do you think this mutation will affect its ability to mate and/or reproduce?

5. Are Bothead babies clones? Explain your answer.
6. Does phenotype determine genotype or vice versa? Explain your answer.
7. Based on your and your partner’s results, please answer the question posed in the Introduction: Why do I look different than my parents or my siblings? (Be as specific as possible!)
8. Thought Question: If the majority of children look different than their parents, how are identical twins or even triplets produced?

Student Worksheet PDF

10611_Student1.pdf