In a cross between two Labrador retrievers one parent is het

In a cross between two Labrador retrievers, one parent is heterozygous at the two genes that determine coat color in this breed, and the other is homozygous recessive for both genes What are the colors of the parents and what are their genotypes? Calculate the expected phenotypic ratios for their bizarrely large litter of puppies using a Punned square (no need to write out the genotypes or genotypic ratios unless it helps you in working the problem). You are trying to determine the mode of inheritance for a monogenic character with two phenotypes: blue or red eye color. You cross a red-eyed female to a blue-eyed male and obtain 50 blue-eyed females and 50 red-eyed males. What is the mode of inheritance for this color character? Explain the logic you used to arrive a your answer and define the genotypes of the red-eyed female and blue-eyed male you used in your cross.

Solution

6. (A) The genotypes of the parent is BbEe and bbee. The color of the parents is black and yellow.

6.(b) The cross will be BbEe * bbee. On selfing, the gametes will be BE, bE, eB, eb, eb

The ratio will be 1:1:1:1. one black, one chocolate, one yellow with black pigment, one yellow with chocolate pigment.

7. The mode of inheritance for this eye color is autosomal dominant. The genotypes are X^RX^R and X^BY. Since the blue eye color is dominant over red color so cross yields 50 red eyed male and 50 blue-eyed males. The inheritance is autosomal dominant because in this case only one set of an allele is required to show the phenotype. So only one allele for the blue color is enough for its expression.

	BE	bE	eB	eb
eb	BbEe	bbEe	eeBb	eebb