BIO 325 Genetics Problem Set 3 Review Questions 2026/27 Latest - UT
Austin
1. We say that crossing over is reciprocal. What does that mean for the products of crossing over.
2. Explain how, if the chromatids of two homologous chromosomes crossover 100% of the time, it gives
a recombination frequency of 50%.
3. If, given the genotype of the individual as A—B/a—b, we get 50% crossover, what should kinds of
gametes should be produced and in what ratios?
4. Recombination frequencies = map distances meaning how far two genes on the same chromosome
are apart. Explain Recombination frequency is related to how far two genes are apart.
BIO 325 Genetics Problem Set 3
, 5. Use the crossover frequencies below to generate a map of ABCD and how far they are apart.
Gene Frequency of Crossover
A-C 30%
B-C 45%
B-D 40%
A-D 25%
6 Five Lysine-auxotrophic bacterial strains (1-5) have been identified. Each strain contains a single
mutant gene. Supplements A, B, C, E, F are intermediates in the Lysine Biosynthesis Pathway.
Supplement D is Lysine. The “+” in the table indicates that the strain will grow if given that supplement,
an “-” means lack of growth. List the order of supplements in the pathway from the first step to last
step.
BIO 325 Genetics Problem Set 3
Austin
1. We say that crossing over is reciprocal. What does that mean for the products of crossing over.
2. Explain how, if the chromatids of two homologous chromosomes crossover 100% of the time, it gives
a recombination frequency of 50%.
3. If, given the genotype of the individual as A—B/a—b, we get 50% crossover, what should kinds of
gametes should be produced and in what ratios?
4. Recombination frequencies = map distances meaning how far two genes on the same chromosome
are apart. Explain Recombination frequency is related to how far two genes are apart.
BIO 325 Genetics Problem Set 3
, 5. Use the crossover frequencies below to generate a map of ABCD and how far they are apart.
Gene Frequency of Crossover
A-C 30%
B-C 45%
B-D 40%
A-D 25%
6 Five Lysine-auxotrophic bacterial strains (1-5) have been identified. Each strain contains a single
mutant gene. Supplements A, B, C, E, F are intermediates in the Lysine Biosynthesis Pathway.
Supplement D is Lysine. The “+” in the table indicates that the strain will grow if given that supplement,
an “-” means lack of growth. List the order of supplements in the pathway from the first step to last
step.
BIO 325 Genetics Problem Set 3
