Reebop Genetics

Reebop Genetics

Purpose: To demonstrate the process of how genes are passed from parents to offspring, the concept of dominant and recessive traits, and the difference between genotype and phenotype.

Background:

Heredity is the passing of physical characteristics, or traits, from parents to offspring. Traits, such as stem height or hair color, vary between individuals and are determined by genetic material inherited from each parent. Scientists use the term "gene" for the unit of genetic material that controls a specific trait. Alleles are the different forms of a gene.An organism inherits one allele from each parent, so every gene is controlled by a combination of two alleles. A dominant allele is one whose trait always shows up in the organism when that allele is present. A recessive allele is hidden or masked whenever the dominant allele is present. The allele combination or genetic makeup of an organism is called its genotype, while its physical appearance is called its phenotype. Genotypes are represented by 2 letters, one for each allele (i.e. AA, Aa, or aa). The dominant allele is usually a capital letter (i.e. A) and the recessive allele is usually a lower-case letter (i.e. a). A genotype may be homozygous for a trait if an organism has two identical alleles, or heterozygous for a trait if an organism has two different alleles.

Materials:Styrofoam balls, toothpicks, pipe cleaner, thumb tacks, paper clips, push pins, paper chromosomes

Procedures:

You will work with a partner for this activity. One of you will be the MOM Reebop and one of you will be the DAD Reebop.

1. Take your chromosomes out of the envelope (Mom = pink, Dad = blue), and match like letters together. Keep Mom and Dad chromosomes separate.

2. These chromosomes are the parent genotypes. Record these genotypes in Table 1.

3. Arrange the chromosomes on the table so that they are face down in height order (biggest to smallest).

4. Take turns picking one allele from each set of chromosomes and set them aside. These will be the alleles that your Baby Reebop will inherit.

***Double check that you have 16 alleles total: 8 pink and 8 blue!

5. Match up the alleles for each letter (1 pink with 1 blue). These are the genotypes that your Baby Reebop will inherit. Record these genotypes in Table 2.

6. Determine your Baby’s phenotypes from the genotypes that you recorded.

***You must get approval before building your Baby Reebop!

7. Using the phenotypes you determined, build your Baby Reebop with the appropriate materials. Name your Baby Reebop and record who the parents are.

Data:

TABLE 1: Parent Genotypes

TABLE 2: Baby Genotypes and Phenotypes

Analysis Question:

1. In humans, the allele for free earlobes (F) is dominant over the allele for attached ear lobes (f).

a. What possible genotypes could a person with the free earlobe phenotype have?

______

b. What possible genotypes could a person withattached earlobes have?

______

Table 3: Rebops - Genotypes to Phenotypes*

*All traits are completely dominant

Standards Addressed:

Genetics

2.b. Students know that sexual reproduction produces offspring that inherit half their genes from each parent.

2.d. Students know plant and animal cells contain many thousands of different genes and typically have two copies of every gene. The two copies (or alleles) of the gene may or may not be identical, and one may be dominant in determining the phenotype while the other is recessive.

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