Heterozygous Cp cp chickens express a condition called creeper, in which the leg
ID: 87082 • Letter: H
Question
Heterozygous Cp cp chickens express a condition called creeper, in which the leg and wing bones are shorter than normal (cp cp). The dominant Cp allele is lethal when homozygous. Two alleles of an independently segregating gene determine white (W-) versus yellow (w w) skin color. From matings between chickens heterozygous for both of these genes, what phenotype classes will be represented among the viable progeny and what are their expected relative frequencies? Ranch mink with the dark gray coat color known as Aleutian are homozygous recessive, aa. Genotypes AA and Aa have the standard deep brown color. A mating of Aa X Aa produces 8 pups. a. What is the probability that none of them has the Aleutian coat color? b. What is the probability of a perfect 3:1 distribution of standard to Aleutian?Explanation / Answer
8. The genotype of the parents is CpcpWw. The possible gametes are CpW, Cpw, cpW and cpw. The cross would look like the following:
The displayed genotypes and their frequencies are:
Creeper, white: 6
Creeper, yellow: 2
Normal, white: 3
Normal, yellow: 1
CpW Cpw cpW cpw CpW CpCpWW (non-viable) CpCpWw (non-viable) CpcpWW CpcpWw Cpw CpCpWw (non-viable) CpCpww (non-viable) CpcpWw Cpcpww cpW CpcpWw CpcpWw cpcpWW cpcpWw cpw CpcpWw Cpcpww cpcpWw cpcpww