BIOLOGY 211 Spring 2010
Suggested Problems
Name
KEY
2. An autosome in the four o’clock plant has the normal sequence of ABCD*EFGH (* is the centromere).
Consider a heterozygote between this normal chromosome and an inversion chromosome that is
AE*DCBFGH. A three-strand double crossover event occurs where one crossing over event occurs
between C and D and the other crossing over event occurs between G and H. First, provide the
chromosome sequence of the four meiotic products. Second, indicate whether each meiotic product is most
likely viable (V) or not viable (N).
First, correctly align the 2 homologues. Second, choose 3
chromatids (in this example, red, yellow, and blue) for the 3 strand
double crossover. Third, trace the chromosomal segments by
starting at one end of a chromatid.
Normal ABCD*EFGH Inversion AE*DCBFGH
D
D
D
D
1
2
3
1
1
3
2
4
CC
C C
BB
B B
A
A
A
A
A BC D*E A
AE *DCBF G H
ABCD*EF GH
HGF BC D*EFG H
1
3
2
4
E E
E E
FG
H
FG
FG
H
H
FG
H
3
2
4
4
Dupli cation/ Deletio n (N) No t Vi abl e
Inversion
Viabl e (V)
Normal
Viabl e (V)
Dupli cation/ Deletio n (N) No t Vi abl e