1. For the following genetics problems, please show your work – I have given you a document on how to solve genetics problems. Do each step! If you need to attach pictures of the Punnett squares, you can attach them. You may also use the “table” function in MS Word and save it that way. Correct answers that do not show your work will be counted wrong.

a. In guinea pigs, smooth coat is dominant over rough coat. Cross a homozygous dominant guinea pig with a homozygous recessive guinea pig. What are the expected genotypes and phenotypes of the offspring?

b. Cross two offspring from the question above (F1 generation). What are the expected genotypes and phenotypes of this offspring (F2 generation)?

c. In guinea pigs black coat is dominant over white coat. Cross two guinea pigs heterozygous for both traits (coat texture and coat color). Predict the genotypes and phenotypes of their offspring.

d. You have a pea plant with yellow seeds and you know that yellow is a dominant trait. However, you do not know if it is true breeding or not. Explain how you would find this out with a test cross, including the different possible results. (Please review the information on test crosses in your book on Figure 11.7 and in the text, so you will know exactly what a test cross is.)

2. Three babies born in a hospital at almost the same time were accidently mixed up. The blood types of the parents are known, as are the blood types of the babies. Using this information, match the correct baby with the correct parents and explain HOW you arrived at this conclusion.

Parents Mother blood type Father blood type
Mendel Type A Type B
Darwin Type O Type AB
Franklin Type B Type O

Baby Baby blood type
Boy 1 Type AB
Boy 2 Type A
Boy 3 Type O
 

3. Polygenetic Inheritance – How do genes determine skin color?

Go to the HHMI: How Do We Get Our Skin Color, watch the short video and answer the following questions:

a. Name 3 factors that determine skin color as presented in the video.

Go to the How Genes Determine Skin Color presentation site to answer the following questions. Note: You will have to continuously refer back to this presentation to answer these questions.

b. If skin color were inherited in a simple dominant or recessive pattern, like seed color in pea plants. What would be the genotypes of dark- skinned parents that could produce fair-skinned children?

c. What other traits are likely to be controlled by multiple genes?

d. What color skin would a person with AaBbCc genotype have?
(Note: Both alleles contribute to the phenotype, so that neither is actually dominant or recessive. See page 230 of your textbook.)

e. Examine the genotypes shown, there is a pattern that explains why polygenes are also called “ADDITIVE.” What is the pattern?

f. What genotypes would you assign to Jonah and Sophia in the simulation?

g. Create five offspring by flipping your coins and record them on a table.
Polygenic Inheritance Data Table (Skin Pigmentation)
Child Genotype Phenotype
1
2
3
4
5

h. What do each of the colored circles on the chart represent? (This is found on the next page in the presentation.)

i. What genotypes and phenotypes are possible in Richard and Catherine’s offspring? Please use the genotypes referenced in the presentation.

j. On the next page of the presentation, read the quote from Catherine regarding her light skinned babies. Do you agree with this quote? Explain your reasoning using your understanding of the genetics of skin color.

k. Based on the information presented in the lecture slide; do you think that the genes for human skin color display codominance or incomplete dominance? Explain your answer.