Week 4 and 5 for Intro to Evolution
Week 4 and 5 for Intro to Evolution BZ 220
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This 3 page Class Notes was uploaded by Courtney Parks on Monday February 22, 2016. The Class Notes belongs to BZ 220 at Colorado State University taught by Angeloni, Lisa Maria in Fall 2016. Since its upload, it has received 41 views. For similar materials see Introduction to Evolution in Biology at Colorado State University.
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Date Created: 02/22/16
Week 4 and 5 Introduction to Evolution Debate o Medelians Followers of Mendel and De, Vries Only discrete variation is inherited/ evolves Evolution/speciation happens rapidly by mutation o Biometricians Followers of Darwin Continuous variation is inherited/evolves Evolution/speciation happens gradually by natural selection Factors of continuous variation o Environment o Co-dominant alleles o Multiple genes affect a trait o Epistasis Interaction of 2 or more genes to control a single phenotype where one genes interferes or masks the phenotype expression of another gene o Recombination and sex Mutations Structure and coding o Nucleotides form DNA o DNA codes for proteins Triplet can only code for 1 amino acid Multiple triplets code for one amino acids o DNA repair enzymes can fix mistakes Causes o Environmental agents o DNA replication mistakes Nucleotide mutations o Substitutions Transitions Transversions Can by synonymous or nonsynonymous o Insertions and deletions- frameshift mutations o Synonymous substitution- doesn’t change amino acid o Nonsynonomous substitution Mis-sense changes single amino acid Non-sense changes to a stop codon o Gene duplication- source of new genes Chromosome inversion o Order is inverted or switched o Part of chromosome breaks off and doesn’t reattach to correct part o Suppresses recombination o Alleles within inversion are inherited together without recombination Chromosome translocation o Swapping of genetic material between 2 non-homologous chromosomes o Loses chromosome o Decreases fertility Chromosomal division errors in women o Extra copy of chromosome o Likelihood increases with age o Odd # chromosomes messes up fertility Chromosome polyploidy o Duplication of entire sets of chromosome o 2n self fertilizes or fertilizes with another 2n creates tetraploidy (4n) o Can create new species Neutral mutations o Not in coding region o In coding region but doesn’t change amino acid o Changes amino acid but not function o Only functional effect in certain environments Men vs. Women o Spermatogonal stem cells continuously replicate which increases opportunity for mistake Need to Know about Humans o 20,000-25,000 genes in haploid genome o 1.6 mutant proteins per individual o 175 nucleotide mutations per individual (mostly silent) Population Genetics Allelic Diversity- having multiple alleles for a given gene at the population level Heterozygosity o Fraction of genotypes that are heterozygous Allele frequency o Number of copies of given allele divided by total number of copies of all alleles Genotype frequency o Number of individuals of given genotype divided by total number of individuals Hardy- Weinberg Equilibrium Principle o Explains how genetic variation is maintained without and forces acting o Shows that allele and genotype frequencies remain constant across generations if no forces met in a population o Assumptions No selection If violated can No mutation No migration change in allele No genetic frequencies in drift evolution Random mating If violated can change o Testing it genotype frequency 1. Measure allele frequencies across generations to see if they change 2. Ask if the observed genotype frequencies match what we expected them to be, based on HWE from the allele frequencies o Conclusions Allele frequencies should not change across generations Allele frequencies with p and q, genotype frequencies should be p , 2pq, and q2 Genotype frequencies should not change Allele and genotype frequencies always add to 1 whether the population is in HWE or not
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