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67
Problems
winged male is crossed with a homozygous wild
type female, what ratio of normal to smallwinged
Fies can be expected in each sex in the ±
1
? If ±
1
Fies
are intercrossed, what ±
2
progeny ratios are ex
pected? What progeny ratios are predicted if ±
1
fe
males are backcrossed with their father?
26.
An Xlinked dominant allele causes hypophospha
temia in humans. A man with hypophosphatemia
marries a normal woman. What proportion of their
sons will have hypophosphatemia?
27.
Duchenne muscular dystrophy is sexlinked and
usually affects only males. Victims of the disease be
come progressively weaker, starting early in life.
a.
What is the probability that a woman whose
brother has Duchenne’s disease will have an af
fected child?
b.
If your mother’s brother (your uncle) had
Duchenne’s disease, what is the probability that you
have received the allele?
c.
If your father’s brother had the disease, what is
the probability that you have received the allele?
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This note was uploaded on 01/10/2011 for the course BIOL BIOL taught by Professor Johnson during the Spring '08 term at Aberystwyth University.
 Spring '08
 JOHNSON
 Biology

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