## Answers

The Agouti gene determines coat colour in mice. We can call this gene "A" for Agouti, where A is dominant and a is recessive.

Heterozygous mice have yellow coats: So mice with "Aa" are Yellow.

Homozygous dominant mice have black coats: So mice with "AA" are black.

Homozygous recessive genotypes are lethal for mice: SO mice with "aa" will not survive.

In a population of 2000 mice, 1082 have Black coats (or AA genotypes).

(1082)/(2000)= proportion of .541

*Remember the Hardy Weinberg Equation (p^{2}+2pq+q^{2}=1) and p+q=1 always.

P will equal the square root of p^{2}: √p^{2}= √ (.541) = 0.74

**So the frequency of the A allele is 0.74**

Q will equal 1-p: 1-(.74)= 0.26

**So the frequency of the a allele is 0.26**

The 0.541 proportion is representative of the mouse population with Black coats, or AA population. The Homozygous dominant genotype is represented in the HW equation as p^{2}. So, we can find p by square rooting p^{2}, and q by manipulating the p+q=1 equation.