Molecular Biology of the Gene 7th Edition by Richard Losick, James Watson, Michael Levine, Tamara Baker, Alexander Gann

تمرين 8

You are studying a new species of bird. You know the species has sex chromosomes similar to chicken. Males carry two Z chromosomes, whereas females carry one Z chromosome and one W chromosome. Because the genome has not been sequenced yet, you will perform crosses to gain more genetic information. You are interested in the eye color of the birds. You obtain true-breeding birds with black or green eyes. You cross a black-eyed male to a green-eyed female. Assume the trait is determined by one gene.
A. Considering a dominant/recessive relationship, you want to determine if black is recessive to green or if green is recessive to black. How could you use the phenotypes for the F 1 and F 2 progeny to help you answer this question?
B. If the trait is sex-linked, refine your answer to part A with respect to the dominant/recessive relationship of a sex-linked trait on the Z chromosome for the F 1 generation.
C. Assume that black is dominant to green. You cross a black-eyed male from the F 1 generation to a black-eyed female from the F 1 generation. If the trait is sex-linked, predict the genotypic and phenotypic ratios for the F 2 generation.