Question

Hemophilia is a recessive trait carried on the X chromosome. What are the genotype and phenotype ratios of a cross between a normal woman who is a carrier for hemophilia and a man who is normal?

P——X——

Genotypic ratio?
Phenotypic Ratio?

Answer 1

Step-by-step explanation:

Hemophilia is a sex- linked recessive trait which means that the disease is carried on the sex chromosomes. Females are always represented as, XX. Males are always represented as XY. In this problem you had to cross a carrier female and a normal male. A carrier is a person who carries he disease but doesn't have the disease as it has another dominant allele to mask the recessive allele. Hemophilia is represented as x^r. Down below I have linked the Punnet square to represent the cross.

Genotype Ratio: 1:1:1:1

All the genotypes (actual genes present) are different in all the possible offspring.

Phenotypic Ratio: 3:1

75% of the offspring will NOT have hemophilia, however there is a 25% chance that an offspring can have hemophilia. (3 represents the offspring with hemophilia, and 1 represents the offspring with hemophilia.)

Also none of the females in this situation can have hemophilia, however, one of the females can be a carrier for the disease. One of the males, however, can inherit the disease.