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Name:__________________________ Date:________________ Period:____________
Crossing Over Genetic Recombination Overview
Who Does Crossing-Over Effect?
1.
2.
What is Crossing Over?
When Does it Happen?
During Prophase I of Meiosis
Remember the differences between Mitosis and Meiosis?
Where does Crossing Over Occur?
Genetic swapping occurs between paired homologous chromosomes in our sex cells—
1.
2.
New genetic material has been acquired from the other homologue
NOTE: Genes that have a tendency to remain together during crossing over are said to be linked.
Why Does Crossing Over Occur? To provide genetic variation during meiosis
Its Why You and I Don’t Look Alike
Crossing Over ensures a ____________________ of the maternal and paternal genes we inherited
The History of Crossing Over
•Gregor Mendel, 1823-1884
•Carl Correns, 1900s •Alfred Sturtevant -
Crossing Over Basics
Occurs at One or More Points Along Adjacent Homologues during Synapsis
•Points contact each other
and DNA is Exchanged
–Gene Mapping Tracking crossing over helps determine where genes are located on the chromosome
–Genes that are far apart have a ______________chance of crossing over
–Genes that are closer have a _________________________ chance of crossing over
•Genes that stay together are said to be _____________________
•One gene can be identified as a ___________________ that can infer the presence of the other gene
–This can be used in identifying disease predisposition
http://www.dnaftb.org/dnaftb/11/concept/index.html
HS_4_Crossing_Over_Notes