Question

In mice, agouti fur is a dominant trait resulting in individual hairs having a light band of pigment on an otherwise dark hair shaft. A mouse with agouti fur isshown here, along with a mouse with solid color fur, which is the recessive phenotype (A = agouti; a = solid color).

A separate gene,which is not linked to the agouti gene, can result in either a dominant black pigment or a recessive brown pigment (B = black; b =brown).

A litter of mice from the mating of two agouti black parents includes offspring with the following fur colors:

• solid color, black
• solid color, brown (sometimes called chocolate)
• agouti black
• agouti brown (sometimes called cinnamon)

In the same mouse species, a third unlinked gene (gene C/c) also has an epistatic effect on fur color. The presence of the dominantallele C (for color), allows the A/a and B/b genes to be expressed normally. The presence of two recessivealleles (cc), on the other hand, prevents any pigment from being formed, resulting in an albino (white) mouse.

Match the phenotypes on the labels at left to the genotypes listed below. Labels can be used once, more than once, or not at all.

Label-Albino, Agouti brown, Sold color black, Agouti black, Solid color brown.

AaBbcc - ?

AaBBCC -?

Aabbcc -?

AAbbCc -?

aaBbCc -?

AABBcc-?

In the same mouse species, a fourth unlinked gene (gene P/p) also affects fur color.

• For mice that are either homozygous dominant (PP) or heterozygous (Pp), the organism’s fur color is dictated by the other three genes(A/a, B/b, andC/c).
• For mice that are homozygous recessive (pp), large patches of the organism’s fur are white. This condition is called piebaldism.

In a cross between two mice that are heterozygous for agouti, black, color, and piebaldism, what is the probability that offspring will have solid black fur alongwith large patches of white fur? (Hint: Consider each gene separately; then use the multiplication rule. For more help getting started, see Hint 1.)Express your answer as a fraction using the slash symbol and no spaces (for example, 3/16).

Answer 1

The recessive phenotype is controlled by the homozygous aa genotype. So the recessive phenotype is the solid colored mouse.

Answer 2

are you retarded

Answer 3

question