MCDB Christoffersen Lecture #5

MCDB Christoffersen Lecture #5 - MCDB Christoffersen...

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MCDB Christoffersen Lecture #5 Epistasis Two or more genes interact to influence a single phenotype Modified 9:3:3:1 ratio in dihybrid cross 9:3:4 phenotypic ratio is one example of epistatic gene interaction Linkage and Fruit Flies T.H. Morgan and colleagues studied Drosophilia melanogaster (fruit fly) Reason was that it has a large # of progeny in a small space, and a 12 day life cycle. Linkage: o Two genes on the same chromosome that tend to be inherited together. o Linked genes do not assort independently o Dihybrid cross of two linked genes will not give 9:3:3:1 in F 2 progeny o Dihybrid testcross of two linked genes will not give 1:1:1:1 ratio of phenotypes o Two genes are near each other, is when linkage occurs. It doesn’t obey Mendel’s second law. A hypothesis was purposed that alleles for different characteristics always assort independently. The conclusion showed that genes do not assort independently, but are linked on the same chromosome.
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This note was uploaded on 01/19/2012 for the course MCDB 1a taught by Professor Feinstein during the Fall '08 term at UCSB.

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MCDB Christoffersen Lecture #5 - MCDB Christoffersen...

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