BLY302
FALL 2010
PRACTICE PROBLEMS FOR EXAM 2
Q1
If the recombination frequency between genes (
A
) and (
B
) is 5.3%, what is
the distance between the genes in map units on the linkage map?
Q2
Assume that the coefficient of coincidence (CC) for a map distance of 24 cM
= 0.25.
Consider the following 3factor (trihybrid) testcross:
+
+
c
(x)
abc/abc
a
b
+
10.6 cM
13.4 cM
Calculate the number of progeny in each phenotype class (parentals, SCOs, and
DCOs) resulting from this cross.
Base your calculations on a total of 1000
progeny.
Hint:
The actual frequency of
doublecrossover progeny
can be determined
by multiplying the frequencies of recombination for each single crossover
together (to calculate expected DCOs), and then multiplying that product by the
coefficient of coincidence for the known map distance between the alleles (to
calculate the actual, observed DCOs).
Q3
You are studying 3 genes X, Y, and Z that are linked (in that order) in the
Imperial Scorpion
Pandinus imperator
.
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 Fall '10
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 Genetic linkage, amino acid sequence, Mendelian Inheritance

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