Lecture 43

Question 1

Gene 1and gene 2 can interact if:

Answer 1

on different autosomes
on same autosome
on an autosome and on a sex chromosome
one same sex chromosome

Question 2

What is penetrance?

Answer 2

% individuals with mutant allele that have mutant phenotype

Question 3

What is expressivity?

Answer 3

how much the mutant phenotype varies (lots of variation is broad expressivity)

Question 4

Why are there variations in phenotypes?

Answer 4

random chance (piebald mutation Sp = white patches in beagles, complete penetrance, broad expressivity)

genetic background (other genes alter phenotype of gene of interest

environment (siamese cats, enzyme works at cool body temp only)

age (such as bell peppers)

Question 5

What is the gene responsible for fur colour in siamese cats? Where does it work?

Answer 5

tyrosinase GLY227TRP

works at cool body temperatures

extermities = pigment

warm areas = no pigment

Question 6

labradors fur coat biochem pathway

Answer 6

recessive epistasis