You discover a gene that results in a complete lack of hair in rats, and you name the gene "chromedome." A cross of homozygous normal and homozygous bald rats results in all bald rats. You conclude that the baldness allele is dominant, but when you repeat the cross with different rats none of the offspring are bald. Extremely puzzled you study your records and discover that in the first cross the bald rat was female, while in the second cross the bald rat was male. What do you conclude from this information?

Question

Quizplus · Accepted Answer

Chromedome is imprinted in females.In the first cross, the bald rat was female, and all the offspring were bald. This suggests that the baldness allele is dominant in females. In the second cross, the bald rat was male, and none of the offspring were bald. This suggests that the baldness allele is recessive in males. This is consistent with the phenomenon of genomic imprinting, in which a gene is expressed differently depending on whether it is inherited from the mother or the father.

You Discover a Gene That Results in a Complete Lack