Quantitative Traits

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Quantitative Traits
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Quantitative TraitsDistribution of Corn Ear
Lengths
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Mendelian Explanation of a Quantitative Trait
Very small Small Medium Large Very
Large 1 4 6 4
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Study Question 3
How many discrete lengths would you predict to be
possible if there were four identical Height
genes?
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ComplementationMultiple Infection
Multiplicityof Infection Phage/Hosts
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ComplementationFailure to Complement
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Complementation
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Study Question 4

• 5 mutants of phage T2
• Mutants forms tiny plaques
• Complementation tests - coinfect E. coli with
  pairs
• How many genes are required for the wildtype
  phenotype?

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Study Question 5-7
Cross female 34 extra hairy x male 43 (Curly
hair) Possible genotypes of parents?Genotypes of
F1 progeny?
One gene hypothesis
34 EE x 43 CC EC
Two gene hypothesis
34 EE x 43 CC E
C
Two gene hypothesis/one X-linked
XXE CXE Y C
34 XEXE x 43 XY CC
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Recombination
Nicked strand invades other chromosome
One strand nicked
Homologous chromosomes pair
Other strands break
Recombination complete
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Recombination
No change (sequences are identical except for
sites of mutation)
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Recombination
Two novel DNAs, different from parents
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Complementation vs Recombination
Complementation
Recombination acts through protein acts
through DNA temporary
permanent efficient
rare useful to define genes
useful to map genes