BIOL 120 1st Edition Lecture 17 Outline of Last Lecture I Overview of Meiosis II Mitosis vs Meiosis III Crossing Over IV Results of Meiosis V Mendel s Experiment Outline of Current Lecture I Experiment method and Five Element model II Monohybrid crossing III Principle of Segregation IV Punnett Squares V Dihybrid crossing VI Human Blood Groups VII Environmental influence and other main ideas Current Lecture I Experiment method and Five Element model A 3 stage process 1 Produce true breeding strains for the trait being studied 2 Cross fertilize true breeding strains These notes represent a detailed interpretation of the professor s lecture GradeBuddy is best used as a supplement to your own notes not as a substitute 3 Allow hybrid offspring to self fertilize for several generations and count number of off spring showing each trait B Five Element Model 1 Parents transmit genes 2 Each individual receives one copy of a gene from each parent 3 Not all copies of a gene are identical a homozygous 2 of the same allele RR or rr b Heterozygous different alleles Rr 4 Alleles remain discrete and do not blend hypothesis when Mendel was conducting his experiment 5 Presence of allele does not guarantee expressions a dominate allele always shows over recessive b recessive only shows if both alleles are recessive genes II Monohybrid crossing A a process that studies only 2 variations of a single trait B F1 generation the offspring produced from 2 true breed strains 1 only shows dominant traits C F2 generation second filial generation offspring of F1 1 result from the self fertilization of F1 plants 2 recessive traits begin to reappear in F2 3 Phenotypic ratio of 3 dominate 1 recessive 4 Genotypic ration 1 homozygous dominant 2 heterozygous dominant 1 homozygous recessive D Genes hereditary determinants for a trait E Alleles different versions of a gene usually 2 F Genotype allelic make up of an individual G Phenotype physical manifestation of genotype in an environment III Principles of Segregation A Idea two alleles for a gene segregate during gamete formation and are rejoined at random one from each parent IV Punnett Squares A a method used to determine possible genotypes B Example of F2 generation V Dihybrid Crossing A is the examination of 2 separate traits in a single crossing event B F1 generation stills shows only dominant phenotypes C F2 generation ratio 9 dominant dominant 3 dominant recessive 3 recessive dominant 1 recessive recessive D Test Cross 1 a cross used to determine the genotype of an individual with dominant phenotype a you cross the individual with an unknown genotype P with a homozygous recessive pp in order to solve the unknown E Incomplete Dominance 1 heterozygote is intermediate in phenotype between 2 homozygotes i e a red and a white flower produce a pink flower F Codominance 1 heterozygote shows some aspects of the phenotype of both homozygotes i e blood type AB A and B are both dominant so being together makes them both appear in phenotype VI Human Blood groups A Has multiple alleles 3 1 Type A blood A is dominant 2 Type B blood B is dominant 3 Type AB A and B are codominant universal receiver 4 Type O blood has no dominant universal donor VII Environmental Influence and Other main Ideas A Environmental Influence 1 temperature affects the amount of pigment alleles allow enzymes to produce B Epistasis 1 The behavior of gene production can change the ratio expected in independent assortment not 3 1 C Polygenic inheritance 1 occurs because multiple genes are involved in controlling the phenotype of a trait phenotype is a buildup of multiple genes 2 traits show continuous variation known as quantitative traits i e human height D Pleiotropy 1 is an allele that has more than one effect on the phenotype cystic fibrosis a multiple symptoms can be tracked back to one defective allele