Yellow mice possess a dominant effect allele at the gene locus that controls coa
ID: 68829 • Letter: Y
Question
Yellow mice possess a dominant effect allele at the gene locus that controls coat color that is lethal when homozygous. Let Y = yellow, dominant, and y = agouti, recessive. All yellow mice have a genotype of Yy at this locus. There is also a gene "C" that controls whether the coat color gene can even be expressed. Let C = pigment production, dominant, and c = no pigment production (or albino). Thus, a yellow mouse would have to have a genotype of C_,Yy. Also, an albino mouse could be homozygous YY because the recessive cc genotype prevents the coat color locus from expressing at all.
a) An albino mouse is crossed with a pure-bred agouti mouse and all F1 offspring are yellow mice. What are the genotypes of the two parents and the F1 offspring?
b) What phenotypic ratio is expected from the cross of two F1 yellow mice?
Explanation / Answer
a). An albino mouse is crossed with a pure-bred agouti mouse and all F1 offspring are yellow mice.
PARENTS: YYcc (albino) X CCyy (agouti)
F1 GENERATION:
Genotypes of two parents are: YYcc and yyCC
Genotypes of F1 : YyCc (all yellow offspring)
b). Cross of two yellow offspring:
YyCc X YyCc
Phenotypic ratio :
6 yellow mice (YyCC and YyCc) , 2 albino ( YYcc), 3 agouti ( yyCc and yyCC), 4 lethal (YYCc and YYCC), 1 yycc
yC yC yC yC Yc YyCc YyCc YyCc YyCc Yc YyCc YyCc YyCc YyCc Yc YyCc YyCc YyCc YyCcRelated Questions
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