bild3midterm

bild3midterm - Mutations 1) Duplications: retrotransposons:...

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Mutations 1) Duplications: retrotransposons: carry genes and insert copies of them into genome -moths and transposons: desaturase performs last step in sex attractant molecule synthesis. The transposable element ezi was inserted into the genome into the desaturase enzyme gene. There is unequal crossing over between inserted ezi copies and copies of ezi nearby on the same chromosome have given rise to new desaturase genes. Genes duplicate and diverge and yield different desaturases. Rapid evolution of gene=speciation. -Adaptive immunity (ability to detect invading organisms/molecules when they have entered host cells; interaction between antibodies and antigens): transposable elements caused evolution of adaptive immunity; jawed/bony fish=adaptive immunity: prey would injure fish’s gut, so this could’ve triggered adaptive immunity -the antibody producing gene is broken into small fragments, the body chooses V,D,J,C fragments and their sequence for antibody mRNA to make the antibody protein -RAG 1 and RAG 2 recognize recognition signals next to D and V, cut this area, loop this DNA (deleted unneeded) region and generate recombined V and D regions Natural Selection - changes allele frequencies -disrupts Hardy-Weinberg law - acts on phenotypes, not genes: the visible, biochemical and behavioral characteristics are changed -effects generations depends on the extent to which selection results in changes in gene pool, which depends on size of genetic contribution to phenotypic differences (some mutant alleles are neutral in their effects) -phenotypic variation can be present even if there is no genetic variation (due to different environmental conditions during development) -environmentally caused pheno variation=not genetically heritable: Johannsen and his beans: artificial selection to size: picked largest or smallest and saw that size was unchanged: not linked with genetics (no genetic variation) -Daphne Major’s finches: Grant caught/tagged/released all finches on island: deep billed finches survived b/c could eat tough seeds (during drought). After drought: small billed finches matured quickly/had more offspring when small seeds became plentiful *DIRECTIONAL SELECTION* (too much directional selection=reduces genetic variability: alleles that contribute to other phenotypes are being lost) -narrow-sense heritability: some phenotypic variability must be result of genetic variation, and the variation must be selectable to change the allele frequencies of the population -heritability of character: measure heritability with gain/reach (what you got/what you wanted) PROBLEM: environmental change makes a character look heritable when it is not -SOLUTION: heritabilities estimated my measuring the correlation between parents and offspring (Mean bill depth of parental birds that survived the drought=midparent value) regression of offspring values on midparent values was calculated; genetic variation was shown to be important component of pheno. variation for bill depth
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This note was uploaded on 04/20/2008 for the course BILD 3 taught by Professor Wills during the Fall '07 term at UCSD.

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bild3midterm - Mutations 1) Duplications: retrotransposons:...

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