BIO207H5 Lecture Notes - Lecture 8: Reginald Punnett, Synteny, Genetic Linkage

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5 Aug 2016
School
Department
Course
Professor
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May or may not be better to read chapter 5 to understand this topic
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Tutorial 5 is based on this lecture, but not test 2.
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Recap from last lecture
alleles assort independently
final allele distribution is random
Parental chromosomes = 100% in the gamete pool
So Parental gametes 100%
Parental chromosome combination 100% for each gamete (non-parental gametes)
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Genes on different chromosomes
No Genetic Linkage
Syntenic genes : Genes on the same chromosome
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Crossing over (frequency) αto distance
Crossing over occurs between homologs
Alleles do NOT assort independently
Final allele distribution is NOT random
Parental >> recombinant chromosomes because crossing over does not happen
too often
Recombinants α to crossing over
Parental chromosomes have not been altered (no crossing over)
Parental chromosomes 100%
Recombination frequency, expressed as r, is calculated as R = number of recombinants /
total number of progeny
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When syntenic genes 'fairly' close to one another in distance (will be explained in later lecture)
Incomplete Genetic Linkage
Syntenic genes
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Crossing over αto distance -> cannot occur
Alleles cannot assort independently
Final allele distribution is NOT random
Parental chromosomes = 100%
because of non-parental gametes
Whenever we have >1 chromosome pairs (homolog pairs)
Parental chromosome combination 100%
Parental gametes = 100%
When syntenic genes are 'very' close
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Complete Genetic Linkage
Syntenic genes
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Crossing over occurs very frequently
When syntenic genes are 'very' far
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No Genetic Linkage
Lecture 8
Monday, August 8, 2016
4:00 PM
Lecture Page 1
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