Name __________________________________________
Period ______
Date _____________
Gene Linkage and Mapping
1. The crossover frequency between genes E and F is 6%, between E and G is 10% and between
F and G is 4%. Construct a gene map. Determine the sequence of genes on the chromosome.
2. In 1911, Thomas Morgan collected the following crossover gene frequencies while studying
Drosophila. Bar-shaped eyes are indicated by the B allele, and carnation eyes are indicated by
the allele C. Fused veins on wings (FV) and scalloped wings (S) are also located on the same
chromosome.
Gene Combinations
FV/B
FV/C
B/C
B/S
FV/S
C/S
Frequencies of Recombinations
2.5%
3.0%
5.5%
5.5%
8.0%
11.0%
Construct a gene map. Determine the sequence of genes on the chromosome.
3. Genes A, B, and C are linked genes. A testcross shows that the recombination frequencies
between A and B is 28%, and between A and C is 12%. Determine the linear order of these
genes.
4. There are 4 genes on a single chromosome: A, B, C, and D. They exhibit the following
crossing over frequencies:
a.
b.
c.
d.
e.
A-B = 35%
B-C = 10%
C-D = 15%
C-A = 25%
D-B = 25 %
Determine the order of the genes on the chromosome.
5. For a series of experiments, a linkage group composed of genes W, X, Y and Z was found to
show the following gene combinations. (All recombinations are expressed per 100 fertilized
eggs). Construct a gene map. Determine the sequence of genes on the chromosome.
Genes
W
X
Y
Z
W
–
5
7
8
X
5
–
2
3
Y
7
2
–
1
Z
8
3
1
–
6. Determine the sequence of genes along a chromosome based on the following recombination
frequencies:
a. A-B = 8%
b. A-C = 28%
c. A-D = 25%
d. B-C = 20%
e. B-D= 33%
7. Determine the sequence of genes along a chromosome based on the following recombination
frequencies:
a. A-B = 30%
b. A-C = 9%
c. A-D = 18%
d. B-C = 21%
e. B-D = 12%
f. E-D = 12%
g. E-A = 6%
h. E-C = 3%
i. E-B = 24%
8. Use the table below to map the genes found on this chromosome of a fruit fly.