Question

Application Exercise 4 - Genetics and Inheritance 1. Hemophilia is a disorder that spread via X-linked inheritance pattem; thus mothers pass the allele on to their male offspring Is there a possibility of a female suffering hemophilia? Explain 2. You are informed that, Mr X, who is blood type A marries Mrs Y, a blood type B lady; they give birth to their first child Z who is blood type O. Is this possible? If so explain 3. Explain how/why each parent contributes only one (as opposed to two) allele of each geneto his/her offspring

Answer 1

1. Yes, it is possible that a female can be haemophilic but this condition is very rare. Howsoever here from cross we can understand how a female can be haemophilic. It can only be haemophilic if the male is haemophilic and mates with a carrier female. 25% chances are there that from this female can be haemophilic. 2. Yes the child Z can have blood group O. It is only possible if the Mr. X who is blood group A has alleles I^{​​​​​​A} and i. Mrs. Y has blood group B should have alleles I^{​​​​​​B} and i. Then only child will have 25% chance to get blood group O. Cross is as follows:

Ххч xxч xx x1 x1 x1 x Haemophilic)

3. This occurs according to the mendelian principle of segregation. During gamete formation( meiosis), two alleles for each gene are segregated. Thus each parent randomly contributes only one allele to the offspring.

АВ А В о