NAME:_____________________________            SS#:__________________________

 

L325 Worksheet 10: Due 04/29/05

REMEMBER: The ÒFor CreditÓ problems are due at the end of your learning group.  You must at least make an attempt to answer ALL of the problems Before coming to class.

Recommended Text Problems: Chap. 26: 4, 6, 9, 10; Chap. 5: 1-7, 10-12, 14-15; Hartl: Chap. 1: 1-4; Chap. 3: 5, 6; Chap. 4: 1-4, 9, 13

 

ÒFor CreditÓ Problems: .

 

  1. For each of the following examples, discuss whether it would be the result of neutral mutation or mutation that has been acted upon by natural selection, or both (2 pts.):

 

A.)   When comparing sequences of homologous genes, differences in the coding sequence are most common at the wobble base (i.e., the third base in each codon).

 

 

 

 

 

 

B.)    The frequency of the allele that causes dark coloration in moths is higher in populations found in polluted woods than it is in populations found in unpolluted woods.

 

 

 

 

 

 

 

C.)    For a structural gene, the regions that encode portions of the polypeptide that are vital for structure and function are less likely to show variation than other regions of the gene.

 

 

 

 

 

 

 

 

 

 

 

 

 

  1. A homologous DNA region, which was 20,000 bp in length, was sequenced among four different species.  The following number of nucleotide differences were obtained. 

 

 

Species A

Species B

Species C

Species D

Species A

0

443

719

465

Species B

443

0

744

423

Species C

719

744

0

723

Species D

465

423

723

0

 

Construct a phylogenetic tree that describes the evolutionary relationship among these 4 species.  Your tree should include values that show the percentage of nucleotide differences (2 pts.).

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

3.      Concordance values for bipolar affective disorder is 0.79 for MZ twins and 0.19 for DZ twins.  For depression, concordance is 0.54 among MZ twins and 0.24 for DZ twins.  Which disorder has the greater inherited component? (2 pts.).

.

 

 

 

 

 

 

 

  1. The heritability for egg weight in a group of chickens on a farm in Maine is 0.95.  Are the following statements about heritability true or false. Explain your answer.  (2 pts. Total).

 

A.   The environment has very little impact on the outcome of this trait.

 

 

 

 

B.    Nearly all of the phenotypic variation in this group of chickens is due to genetic variation.

 

 

 

 

C.    Based on this data, heritability for egg weight in a group of chickens in Montana should also be high.

 

 

 

 

 

D.   If the environment changed, the heritability would still be the same.

 

 

 

 

 

 

  1. In a strain of mice, the average 6-week body weight is 25 g.  The narrow-sense heritability for this trait is 0.21 (2 pts.).

 

A.   What would be the average weight of the offspring be if parents with a mean weight of 27g were chosen?

 

 

 

 

 

 

B.    What weight of parents would have to be selected to obtain offspring with an average weight of 26.5 g?