Name______________________________________________________________________Hour__________
Meiosis
In your book:
Chapter 9, section 9.4-end
Chapter 10, section 10.4
Looking ahead- Chapter 10 Genetics: Mendel and Beyond
Book Summaries:
- Life the Science of Biology (with quizzes, animations, key terms, etc…)
o http://bcs.whfreeman.com/thelifewire8e/
More Help:
- Bozeman Phases of Meiosis
o https://www.youtube.com/watch?v=16enC385R0w
- Bozeman Genetic Recombination & Gene mapping
o http://www.bozemanscience.com/genetic-recombination-gene-mapping/
- Crash Course Meiosis
o https://www.youtube.com/watch?v=qCLmR9-YY7o
- Meiosis! Sciencemusicvideos (Mr. W)
o https://www.youtube.com/watch?v=hOuzYLNEuA4
Alfred Sturtevant
Constructed a genetic map.
Predicted that the father apart two genes are, the higher the probability a crossover will occur between them,
and therefore the higher recombination frequency.
The mechanism that breaks the physical connection between genes from the same chromosome = CROSSING
OVER.
A linkage map is a genetic map of a chromosome based on recombination frequencies.
Gene Linkage Example Problem:
Reconstruct the order of the gene map based on the recombination frequencies listed below.
GENE CROSSOVER FREQUENCY
A-C 30%
B-C 45%
B-D 40%
A-D 25%
1. It is usually most efficient to begin with the genes that are farthest apart.
2. Next, begin overlapping genes. It is sometimes more productive to attempt to pick internal genes first.
3. Remember that crossover frequencies cannot exceed 50%
B------------------45------------------C
insert the possibilities for D
D-------------40--------------B-----------------40-------------D---C (could go either way)
blindly choose B-D-C over D-B-C
B-----------------40-------------D----C
insert A and deduce map distances to match the table
B-----15----A--------25--------D--5-C
Correct Answer: BADC
Chromosome mapping worksheet
1. There are 3 genes on a single chromosome: A, B, and C. They exhibit the following crossing over
frequencies:
a. A-B = 35%
b. B-C = 10%
c. C-D = 15%
d. C-A = 25%
e. D-B = 25 %
Determine the order of the genes on the chromosome.
2. 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%. Can you determine the linear order of these genes?
Explain.
3. 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%
4. 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%