Crossing over occurs during which phase of meiosis?
Prophase 1
The frequency of genetic recombination is inversely proportional to _________?
The distance between the genes.
That is, genes that are close in proximity rarely recombine - they tend to be inherited together.
Which two genes are closest in proximity?
recombination frequency
y - w 0.010
w - v 0.297
v - c 0.030
Genes "y" and "w" are closest in proximity since their recombination frequency is lowest (1%)
Interpretation: "y" and "w" are 1 Centimorgan apart.
Explain what is meant by the term "wild-type."
A term that describes a genotype/phenotype that occurs normally in nature.
Define a Three-point Cross study.
These study three geens, with two alleles each (ex. A & a), that are close to each other on a chromosome; they all exhibit linkage when studied in pairs.
Identify this type of cross-over:
A B C
a b c
A B c
a b C
Single cross-over.
Identify this type of cross-over:
A B C
a b c
a B C
A b c
Single cross-over.
Identify this type of cross-over:
A B C
a b c
A b C
a B c
A double cross-over (a switch in the central gene).
Which type of cross-over is the most rare? What does it determine?
A double cross-over.
It determines which gene is central in a Three-point Cross.