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Genetics 320 (EEB/MCB)
TEST ONE
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(1)
[15 points
]
Scientists studying pond scum at ASU have found an organism with
four sexes.
Suppose the parents are AAAa, AAaa, AAAA, and Aaaa.
(a)
What is the probability of getting an AAAA offspring?
This can only occur one way, namely all parents contribute A.
(3/4)(1/2)(1)(1/4) = 3/32
(b)
What is the probability
of getting an AAAa offspring?
Four pathways:
"a" for parent one (P1), or from P2, or from
P3 or from
P4,
A from all others in each case
P(a P1, A others) = (1/4)(1/2)(1)(1/4) =1/32
P(a P2, A others) = (3/4)(1/2)(1)(1/4) =3/32
P(a P3, A others) = 0
P(a P4, A others) = (3/4)(1/2)(1)(3/4) =9/32
hence Prob (AAAa) = (1+3+9)/16 = 13/32
(c)
Given that the offspring is AAAa, what is the chance that Parent four contributed
the a allele?
P(P4 gives a  AAAa offspring)
= ( 9/32 )/ (13/32) = 9/13
(2)
[5 points
]
Recall the ABO blood group locus.
Suppose we examine 10
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This note was uploaded on 06/16/2008 for the course ECOL 320 taught by Professor Weinert during the Spring '07 term at University of Arizona Tucson.
 Spring '07
 WEINERT

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