4. Lethal yellow (Ay) is a mutation at the mouse agouti (Ag) locus that is associated with an all-yellow coat color, obesity, diabetes, tumors in heterozygotes, and preimplantation embryonic lethality in homozygotes. The Yellow coat colour allele is a recessive lethal in mice. When mice are heterozygous (Ag/Ay) the mice have yellow fur (2 marks).
a. If two yellow mice are crossed together, what will be the proportion of agouti and yellow mice in the offspring?
b. A geneticist examined a number of litters from agouti x agouti mice and compared them to litters of yellow x yellow mice. She observed 200 pups in the agouti x agouti litters. How many pups would you expect to find in the yellow x yellow litters?
a. If two yellow mice are crossed together, what will be the proportion of agouti and yellow mice in the offspring?
b. A geneticist examined a number of litters from agouti x agouti mice and compared them to litters of yellow x yellow mice. She observed 200 pups in the agouti x agouti litters. How many pups would you expect to find in the yellow x yellow litters?
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a. AgAy x AgAy = AgAg, AgAy, AgAy, AyAy (lethal)
2:1 ration of yellow:agouti. so Agouti: 1/3 and yellow: 2/3
B. AgAy x AgAy= again 2:1 ratio of yellow:agouti
Since the AyAy genotype is lethal, we would expect 25% lower progeny when compared to the agouti x agouti cross. So .25(200)= 50 and 200-50(lethal genotypes)= 150. We would expected 150 progeny from this cross
2:1 ration of yellow:agouti. so Agouti: 1/3 and yellow: 2/3
B. AgAy x AgAy= again 2:1 ratio of yellow:agouti
Since the AyAy genotype is lethal, we would expect 25% lower progeny when compared to the agouti x agouti cross. So .25(200)= 50 and 200-50(lethal genotypes)= 150. We would expected 150 progeny from this cross