Name(s):_______________________________________________

How Do Genes Determine Skin Color?

Introduction: This case explores how skin color is inherited in humans. The presentation for this case is located at http://biol.co/genskin

Answer the questions as they are presented to you in the story of Catherine and Richard Howarth whose children are suprisingly light skinned compared to their Nigerian mother.

1.  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?

 

 

 

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

 

 

 

3. What color skin would a person with AaBbCc genotype have?

 

 

4. Examine the genotypes shown, there is a pattern that explains why polygenes are called "ADDITIVE." What is the pattern?

 

 

5. What genotypes would you assign to Jonah and Sophia?

 

 

 

6. Create five offspring by flipping your coins and record them on the table.

Child Genotype Phenotype
1    
2    
3    
4    
5    

7. What do each of the colored circles on the chart represent?

 

 

8. What genotypes and phenotypes are possible in their offspring?

 

 

9. Do you agree with this quote? Explain your reasoning using your understanding of the genetics of skin color.

 

 

 

10. Summarize key vocabulary:

a) Dominant and Recessive

 

 

b) Polygenic (Quantitative) Inheritance

 

 

c) Melanin

 

 

d) Genotype and Phenotype

 

 

e) Heterozygote