Many traits are inherited in a Mendelian manner For example

Many traits are inherited in a Mendelian manner. For example, the fur color of cute little guinea pigs is inherited in a Mendelian manner. Two different alleles for a gene controls hair color (B to represent Black allele and b to represent white allele). In a cross between a black guinea pig and a white guinea pig, all of the F1 generation showed the black phenotype. a. If two of the F1 generation offspring (black guinea pigs) were crossed what do you hypothesize the phenotypic and genotypic ratio for fur color would be in the F2 generation? Diagram the cross to describe your answer. b. How could you determine the genotype of the Black fur color guinea pigs? c. If you mated two white guinea pigs what are the genotypes and phenotypes of the offspring?

Solution

Answer:

BB(Black) x bb (white)--------------Parents

B b -----------------------Gametes

Bb (Black)------------------------F1

Bb x Bb------------------F1 x F1

F2:

Phenotypic ratio: Black : White = 3:1

Genotypic ratio: BB : Bb : bb = 1:2:1

b) Black fur color is dominant over white color and the black color appears in both homozygous and heterozygous conditions.

c)

bb (white) x bb (white)

bb (white)

All progeny are white with bb genotype