Chapter 3: Basic principles of Hereditary, Chapter 5:Extensions of Mendel’s Principles, Chapter 6: Pedigree Analysis, Application, and genetic testing, Chapter 25: Population Genetics, Chapters 6b, 9, 11a: The Structure of Chromosomes, Chapter 22: Developmental Genetics and Immunogenetics, Chapter 24: Quantitative GeneticsHeterozygous cross:1:2:1 genotypic ratio, 3:1 Phenotypic RatioGenotype- the set of genes possessed by an individual organismPhenotype- appearance or manifestation of a characteristic in an organismGene- genetic factor that helps determine a trait; DNA sequence that is transcribed into an RNA moleculeAllele- one of two or more alternate forms of a geneLocus- position on a chromosome where a specific gene is locatedHeterozygote- an individual organism that possesses two different alleles at a single locusHomozygote- an individual organism that possesses two identical alleles at a single locusDominance- an allele of phenotype that is expressed in heterozygotes and homozygotes of the allele; the only allele expressed in heterozygotesMendel’s Laws:First Law of Segregation of alleles- Each individual has two alleles coding for a trait- The two alleles separate when gametes are formed- Alleles separate in equal proportionsSecond Law of Independent Assortment- Genes encoding different characteristics segregate independently of each other when gametes are formed- EXCEPTION: Sex linked characteristicsDihybrid Cross- crossing of two traits of two individualsMultiple Gene Crosses- Small punnett squares for each trait- Multiply probabilitiesChi-Squared testMeiosis- Crossing over occurs in prophase I- Crossing over is between homologous chromosomesStages of Meiosis1. Prophase I2. Metaphase I3. Anaphase I4. Telophase I5. Prophase II6. Metaphase II7. Anaphase II8. Telophase IISex Determination and Sex-Linked CharacteristicsSigns of being sex linked- Results in reciprocal crosses not the same- Different phenotypic ratios in the two sexesSex- Determination in Drosophila- Even though they have X and Y chromosomes, Their sex determination system is based on ratio of autosomes to X chromosomeso Females have a 1.0 X:A ratioo Males have a 0.5 X:A ratioo Metafemales have a >1.0 X:A ratioo Metamales have a <0.5 X:A ratioo Intersex flies have a 0.5-1.0 X:A ratioSex ChromosomesHaploid Sets of Autosomes X:A Ratio Sexual PhenotypeXX AA 1.0 FemaleXY AA 0.5 MaleXO AA 0.5 MaleXXY AA 1.0 FemaleXXX AA 1.5 MetafemaleXXXY AA 1.5 MetafemaleXX AAA 0.67 IntersexXO AAA 0.33 MetamaleXXXX AAA 1.3 Metafemale- In mammals sex determination XY SRY gene necessary and sufficient to produce malesX-inactivation- Why did X-inactivation evolve and provide an example of a phenotype associated with X-inactivationSex Determination in Other Species (ESSAY)- Hymenoptera- Haploid/diploid system results in sex specific splicing of Hem- Slipper limpets- position in the stack of limpets determines the sex of the limpet- Bluehead Wrasse- can begin life male or femal, but females can change into males later in life- Temperature dependent- Turtles and alligators hav temperature of eggs determinethe sex of offspring- Polygenic inheritance- multiple sex determination systems occurring at once – tilapia have XY and WZIncomplete dominance- phenotype of the heterozygote is intermediated between to two phenotypes of the two homozygotes (flower coloring)Codominance- The phenotype of the heterozygote includes the phenotype of both homozygotes (blood type)Temperature sensitivity- certain gene products may only function at an optimal temperature, causing expression to be different at different temperaturesPenetrance- not all individuals with the genotype will express the traitMaternal effects- the genotype of the mother influences phenotypes of the offspringSex-influenced traits- expression of the phenotype is different based on what sex is being expressed inABO Blood types- Compound H- No compound H makes you O- Sugars Present:o A-galactosamineo B- Glucosamineo O- none- Genotypes: AO, AB, AA, BB, BO, OO- Antigens indicative of genotype, Antibodies opposite to genotypeLethal genes- homozygote is lethal in utero, so you never observe those offspring, alters ratios that are observed (dominant or recessive)Epistasis- expression of one gene is dependent on the expression of anotherComplementation test- crossing two mutants that have mutation at the same locus, you expect mutation in offspring too. If you cross two mutants and they have mutations at different loci than you expect some normal offspringPedigree AnalysisPre-natal Testing- Aneuploidies of autosomal chromosomes in humans often produce offspring that don’t survive, aneuploidies in sex chromosomes can surviveHardy-Weinberg Equation- p^2+2pq+q^2=1- Chi-squared test to determine whether a population is in hardy-weinberg equilibrium1. Find Allele frequencies2. Determine genotypic ratios3. Perform chi-squared testCauses of deviations from hardy-weinberg:- Inbreeding (no change in allele frequency)o Loss of heterozygosity over timeo Heterozygote crossing leads to more homozygotes over time- The 4 forces (changes in allele frequency)o Random genetic drift- random fluctuations in allele frequency due to sampling small numbers of gametes each generation, genetic drift causes allelic frequencies in populations to diverge and often become fixed for one allele or the othero Mutation- change allele frequency slowly, millions of generations to cause a substitution, ultimate force in evolutionary changeo Migration- only very high levels of migration, from a population with a very different allele frequency will be detected as a deviation from hardy-weinberg expectationso Selection- many ways for natural selection to act Against ressesive alleles Against dominant alleles Against incompletely dominant allele Overdominance UnderdominanceGenetically effective population size- individuals that contribute to the next generationGenetic drift equation:€ s2p=pq2N€ Δq = m(qI− qII)The structure of chromosomes- Organisms may not be more complex based on number of chromosomes- CoT CurvesChromosome packing in eukaryotes- H1, H2A, H2B, H3, and H4 histone proteins- Nucleosomes/ Chromatosome- Soleniod- Scaffolding proteinsChromosome packing in prokaryotes- Tightly wound circular DNACentromeres-Telomeres-Telomerase-Chromosome mutationsDeletion-Duplication-Inversion-- Pericentric inversion-- Paracentric inversion-Translocation-Mutation affect on metaphase lining