Question

1.) Two linked genes, A and B, are separated by 20cM. A man with genotype AB/ab marries a woman who is ab/ab. What is the probability that their first child will be Ab/ab?

2.) An individual has genotype Ab/aB. Gene loci A and B are 20cM apart. What is the proportion of expected progeny Ab/ab if a testcross is performed on this individual?

Answer #1

1) The recombination frequency between these gene loci is 20%. The man is expected to produce a total of 20% recombinant gametes, which includes two reciprocal products (10%A/b+ 10%a/B).The mother produces only one kind of gamete (ab). For the first child to be Ab/ab, he/she must inherit a specific recombinant gamete (A/b) from the father (probability = 0.1), and any gamete (a/b) from the mother (probability = 1). So, the final probability of the first child being Ab/ab = (0.1)(1) = 0.1 or this is 10%.

2) Ab= 40%

aB= 40%

AB= 10%

ab= 10%

So, the expected progeny of Ab/ab is

(0.4)(0.1) = 0.04 = 4%.

A and B genes are linked at 20 cM apart. A
genotype with known linkage phase AB/ab is
testcrossed to aa bb. What proportion of the offspring is
expected to be dominant for both genes?
Select one:
A. 80%
B. 40%
C. 10%
D. 20%
E. 0%

A, B, and C genes are linked with
B in the middle. AB are 8 cM and BC are
14 cM apart. If ABc/abC is testcrossed to
abc/abc, what is the number of double crossovers
you would expect to observe if 1000 progeny result from this
testcross with a coefficient of coincidence (C) of
0.36.
Select one:
A. about 11
B. about 4
C. about 14
D. about 8

1. A woman with blood type AB marries
a man with blood type O. What will be the expected blood
types of the children. What would be the genotypes?
2. A woman who has blood type AB
marries a man with blood type A whose mother was type O. What is
the chance that their first child will have as its blood
type: A, B, AB, or O?

Genes a and b are linked with 4% recombination. True breeding AB is
crossed with true breeding ab, and F1 is testcrossed. What is the
frequency of getting Aabb progeny? What about AaBb?

A dihybrid AB/ab was testcrossed to a tester of genotype aabb.
What will be the expected segregation ratio of testcrossed progeny
if the A and B genes were 2% recombination apart on the
chromosome?
Please explain how you got to the answer (don't just give the
answer), I'm struggling to understand my teacher and would like to
know the logic behind it. Thanks

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The cross EEFF X eeff is made, and a testcross is then performed
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