Question

COMPUTER GENERATED GRAPHING & TYPED ONLY

1. (one point) A man who has type B blood fathers offspring with a woman who has type A blood. Their first child, a girl, has type O blood.

a) Diagram this cross and include pedigree information as well.

b) What proportion of the gametes from the mother have the IA allele?

c) What would be the probability that their SECOND child, assuming they have one, will have type O blood? Diagram this cross as well and include pedigree information if needed to explain your conclusion.

2. (one point) A man and a woman walk into a genetic counselor’s office. The man’s brother has recently been diagnosed with Duchenne muscular dystrophy. The woman has no history of the illness in her family.

a) They are concerned about having an affected child themselves. The woman is pregnant with a girl. Diagram this cross. What is the chance that the child the woman carries will have the disorder?

b) If they have additional children, would a sperm or egg donor help to decrease the chance of an affected child?

Answer 1

                                                       Possible genotypes     

Father type B Blood Group             BO                                     

Mother type A Blood group            AO                                      

	B	O
A	AB	AO
O	BO	OO

b) the mother will produce two gametes: I^A and I^O

Thus, 50% of the gametes will carry I^A

c) 1/4

2. a) Since the man and his brother will carry 1/2 similar genes, the probablity that the man is carrying the gene is 1/2. As Duchenne muscular dystrophy. shows X linked recessive inheritance, the probability that the girld child will have the diseases is 1/4. This is because 1/2 of the X chromosome will be from father and 1/2 from mother. 1/2*1/2 =1/4

b) Yes. A sperm donor would reduce the chances.