Lecture 8a Student

Lecture 8a Student - Announcements • Will be posted later...

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Unformatted text preview: Announcements • Will be posted later today – Quiz #3 due 2/6 11:59PM – Problem set #2 due 2/10 11:59PM 6-1 M utations ar e the sour ce of new alleles • M ultiple alleles ar ise spontaneously in natur e due to chance alter ations in genetic mater ial • M utation r ate var ies fr om 1 in 10,000 to 1 in 1,000,000 per gamete per gener ation. • Allele fr equency is the per centage of the total number of gene copies r epr esented by one allele. • Wild-type – allele whose fr equency is mor e than 1% • M utant allele – allele whose fr equency is less than 1% • M onomor phic – gene with only one wild- One gene may contr ibute to sever al visible char acter istics • Pleiotr opy – single gene deter mines mor e than one distinct and seemingly unr elated char acter istics • Some alleles may cause lethality. – Type of pleiotropy where alleles produce a visible phenotype and affect viability – Alleles that affect viability often produce deviations from a 1:2:1 genotypic and 3:1 phenotypic ratio predicted by Mendel’s Laws. Fig. 3.9 A- A y A aa Agouti Yellow Black Pleiotr opy: inher itance of coat color Fig. 3.9 Pleiotr opy: inher itance of coat color Agouti x Yellow yields 1:1 agouti:yellow – Yellow must be A Y A – A Y is dominant to A Ratio is 2:1!! Fig. 3.9 Yellow x Yellow mice do not br eed tr ue. – A Y is a recessive lethal. – A Y A Y die in utero and do not show up as progeny Ratio of Yellow is 2:1!! Pleiotr opy: inher itance of coat color Pleiotr opic effects of the mouse lethal yellow(Ay) mutation explained by deletion of a mater nally expr essed gene… Duhl et al. 1994. Development 120:1695 • A y mutation is caused by a 120 kb deletion of RNA-binding pr otein Mer c/Raly M ater nally e xpr essed hnR NP C...
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This note was uploaded on 04/05/2009 for the course BIOL 202 taught by Professor Kieber-hogan during the Spring '08 term at UNC.

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Lecture 8a Student - Announcements • Will be posted later...

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