Lec14Notes - 10/26/10 Summary: "unlinked" genetics...

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10/26/10 1 Chromosomal basis of heredity Principles of Biology Lecture 14 Prof. David Fitch Summary: "unlinked" genetics Mendelian genetics Different alleles encode different traits alleles can be dominant or recessive relative to other alleles In eukaryotes, there are two gene copies per zygote "Law of segregation" maternal and paternal alleles segregate during Meiosis I "Law of independent assortment" segregation at one locus is independent of segregation at another locus Extensions of Mendelian genetics Alleles can be codominant, incompletely dominant, and >2 Different loci can interact in producing a phenotype (epistasis) or many loci can act in the production of a trait (polygenic trait) Genes can be pleiotropic Effect of genes on trait can depend on environment Mendelian "Laws" can be violated genes on the same chromosome may be "linked" temp.-sensitive tyrosinase <33˚C >33˚C Complementation test: Are two different mutations alleles of the same gene? How can you distinguish between these hypotheses? A. If H1, then all of the F1s will be wild type. B. If H2, then all of the F1s will be wild type. C. If H2, then all of the F1s will have the mutant phenotype. D. Both A and C. E. Both B and C. m + m + + n + n H1: the genes m and n are not allelic. m m n n H2: the genes m and n are allelic. X ? X ? Complementation test from Yook, WormBook , ht p:/ www.wormbook.org/chapters/www_complementation/complementation.html Linkage test: Are two different genes linked on the same chromosome? How can you distinguish between these hypotheses? A. If H1, then 1/16 of F1 will be double mutant phenotype. B. If H1, then 1/16 of F2 will be double mutant phenotype. C. If H2, then 1/4 of F2 will be double mutant phenotype. D. Both A and C. E. Both B and C. m + m + + n + n H1: the genes m and n are not linked. m
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This note was uploaded on 11/03/2010 for the course BIOLOGY V23-0011-0 taught by Professor Fitch during the Fall '10 term at NYU.

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Lec14Notes - 10/26/10 Summary: "unlinked" genetics...

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