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Unformatted text preview: 1 Next topic: Extensions of Mendelian Analysis Last lecture: • http://www.esf.edu/efb/powell/inheritance2.pdf • Or go to my homepage, click on teaching, under Genetics click on inhertance2 Extensions of Mendelian Analysis Real world - often more complex same principles, added features understand what a gene produces • enzymes • structural proteins & RNAs • regulatory proteins & RNAs Normal function • alleles > loss of function, reduction of function, or gain of new function Genes can interact Extensions of Mendelian Analysis variation on dominance multiple alleles lethal alleles multiple genes affecting the same character Variations on dominance Example: Four-o ’ clocks (¡ower) P (true breeding) Redx White f 1 all pink (blending of essences? No.) f 2 1/4 red homozygous 1/2 pink heterozygous 1/4 white homozygous 1:2:1 ratio Incomplete dominance heterozygous is intermediate Gene producing an enzyme at the rate- limiting step in a biochemical pathway four-o ’ clock • 2 copies of red allele produces a lot of the enzyme that produces the red pigment - red ¡owers • 1 copy of red allele produces less enzyme - pink ¡owers • 0 copies of red allele produces no enzyme - white ¡owers Incomplete dominance can vary on a scale • Heterozygote intermediate phenotype = 50:50 (50%), 75:25 (75%), 40:60 (40%), etc....
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This note was uploaded on 04/09/2008 for the course EFB 307 taught by Professor Powell during the Fall '07 term at Syracuse.
- Fall '07