Please show work: 1. Hemophilia is a blood disorder in which the blood does not
ID: 211279 • Letter: P
Question
Please show work:
1. Hemophilia is a blood disorder in which the blood does not clot properly. It is a recessive trait which is sex-linked, i.e. it is inherited along with the X-chromosome. Because men have only one X chromosome any gene present on their X chromosome will be expressed.
A normal woman who is a carrier for hemophilia marries a normal man.
a) What are the possible genotypes of their children?**
b) What are the phenotypic ratios?
c) What is the probability that a daughter will have hemophilia? The probability a son will have hemophilia?
d) What is the probability that if the parents conceive that the child (sex unknown) will have hemophilia?
**Note: In figuring this problem remember that the X and Y chromosome synapse and segregate as a pair in meiosis. Therefore, the Y chromosome should be used as the allele of the hemophiliac or normal blood clotting gene in determining the offspring.
Explanation / Answer
When a normal male XY married to a carrier female X'Y the above cross results will be there.
Put of 4 offsprings
1. 25% normal female
2. 25% normal male
3. 25% carrier female
4. 25% haemophilia in male
b. Phenotypic ratio
2 normal : 1 carrier : 1 diseased haemophilia
C. 50% ddaughter will be normal and 50 % will be carrier
. IIn mmale 50%will be normal abdominal rest 50 % will be haemophilia patient.
D. If parent conceived 1 out 4 offspring will have disease thus probability will be 25/100 = 0.25.
X X' X XX normal female XX' carrier female Y XY normal male X'Y haemophilia in male