evo: chp6, 8

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University of Toronto St. George
Jean Jiang Nash

Evolution + Adaptation 03:24 Darwins Finches El Nina -> harder seeds -> finches w bigger beaks survived better Avg beak size of surviving indivi + progeny inc El Nino -> smaller seeds ->smaller beaks survive better Prod more offspring vs. larger beaks Avg size -> lower value Capacity of pop to rsp to changes in env Evo: Traits of indivi win pop = continually adjusted to changes in env Humans = products of genes Differ in genetic makeup Indivi w particular makeup prod greater # of offspring Some variations of genes will be passed on to future generations more freq vs. others Become predominant in pop Changes appear slowly Orgs can rsp to changes in env Pop evo + indivi rsps enable species to adapt to cond of its env Phenotype = outward expression of an indivis genotype Genotype = indivis genes Set of genetic instruction Phenotype = outward expression of genotype in indivis structure + function Renderingexpression of genotype in form of an org Genetic makeup of indivi sets limits on phenotype expression Phenotypic traits have genetic basis + influenced by variations in env Effects of env conditions on indivi Behavioral + physiological rsps of indivi to exhibit diff rsps to env = phenotypic plasticity Genetic Variation Alleles = diff forms of a particular gene Create perceptible + measureable diffs in an orgs phenotype EX. ABO blood types Gene prod antigens A + B (O doesnt prod antigens) Molecules that interact w immune sys Blood type A: AA AO genotypes Blood type B: BB BO genotypes AB or OO genotypes Link bw genotype + phenotype = direct AA father + BB mother = AB geno EX. Eye colour in humans Several genes acting together Reflects influence of at least 3 genes Control pigments of diff parts of phenotype inheritance www.notesolution.comDepend on interactions among the genotypes of each gene Each indivi = 2 copies of each gene 1 from mother, 1 father (except sex-linked genes) heterozygous = 2 diff alleles of a particular gene (AB) 2 diff alleles prod intermediate phenotype codominant 1 allele masks the expression of the other dominant allele recessive allele most harmful alleles = recessive homozygous = 2 copies of a gene are the same (AA) Gene pool = all alleles of all the genes of every indivi in a pop Sexually reproducing pop contain lot of genetic variation United States: 61.3% O, 30.0% A, 8.7% B allele Asians: higher B allele, Irish = O alleles Sources of Genetic Variation Mutation From any change in sequence of nucleotides (ATCG) that make up gene Substitution DeletionInsertion Rearrangement of DNA molecules Inverted regions, duplicated, exchanges of DNA sequences bw chromosomes Cause Lethal changes in phenotype Alter appearance, physiology, beh (esp simple nucleotide substitutions) EX. Tay-Sachs disease, cystic fibrosis, albinism Silentsynonymous mutation No detectable effect Mutations have multiple effects EX. Gene: daf-2 Lengthens life span of roundworm Mutant daf-2 allele Infl expression of other genes + gene regulators Results in many diff effects on life span + physiological processes Pleiotropy = effect of single gene on multiple traits Genetic bass of continuously varying phenotypic traits EX. Body size Most pops, indivi exhibit normalbell-shaped distribution Concentration of indivi toward middle, fewer towards large + small extremes Due to diffs in env indivi exp during development Actions of genes Each have small infl www.notesolution.com
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