Answer 6 of the following 8 questions

2.  Briefly explain how meiosis differs from mitosis.  How does trisomy 21 (Down Syndrome) arise?  Why isn't trisomy 18 a major medical problem?
 

3.  Suppose you are studying mutations in the epinephrine receptor gene.  Explain what effect(s) each of the following mutations might have.

 a. Single base pair mutation in the coding region of the gene.

 b. Single base pair deletion in the coding region of the gene.

 c. Single base pair mutation in the promoter.

 d. Six base pair deletion in the coding region of the gene.

In the course of your studies, you identify some patients who are lacking the epinephrine receptor on the surface of their cells and some patients who have a non-functional receptor on the surface of their cells.  Explain.
 

4.  Several students at Davidson produce a mutant form of wildcatine (the enzyme you identified in the first review).  You are asked to isolate the wildcatine gene.  How would you proceed?

5.  From the following pedigree, explain how the trait in question is inherited.  Provide genotypes (or partial genotypes) for as many individuals as possible.  If person V3 marries person V9, what is the chance they will have an affected son?
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 

6.  In the following cross, AaBbEe x aabbee, you observe the following numbers of phenotypes among the offspring:

 207 A B E                 193 a b e
 199 A B e                  201 a b E
   43 a B E                    53 A b e
   49 a B e                     55 A b E

Explain.
 

7.  In the following cross, AaBb x AaBb, you observe the following numbers of phenotypes among the offspring:

 328 A B           113 A b           98 a B

Explain.

 8.  Among squirrels, albinism is caused by a recessive allele (a).  Suppose among the squirrel population at Davidson, the recessive allele (a) exists at a frequency of 0.04.  If the population is in Hardy-Weinberg equilibrium, what are the frequencies of the various phenotypes and genotypes in the squirrel population?  Suppose we enter an ice age and,because of all the white snow, the relative fitnesses of the genotypes become:

 WAA = 0.25          WAa = 0.25            Waa = 1

What will the allele frequencies be after one generation?
 

9.  The function of the protein encoded by BRCA1, a gene associated with breast cancer, was recently reported. What does this protein do?  Why would mutations in this gene be associated with cancer?  Do you think BRCA1 may be associated with other types of cancer?