BIOL 1441 1st Edition Lecture 25 Outline of Last Lecture I. The Laws of ProbabilityII. The Multiplication RuleIII. Extending Mendelian genetics for a single geneIV. The Spectrum of DominanceV. Multiple AllelesVI. PleiotropyOutline of Current Lecture I. EpistasisII. Polygenic inheritanceIII. Multifactorial traitsIV. Recessively inherited disordersV. InbreedingVI. Dominantly inherited disordersVII. Multifactorial disordersVIII. Appling mendelian genetics to human inheritanceIX. Dominant/recessive inheritanceX. Pedigree analysisCurrent LectureThese 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.I. Epistasis- 2 different genesa. Epistasis- gene at one locus alters the phenotypic expression of a different gene at a second locusb. Mice coat color depends on two genesi. Gene one- determines the type of pigment color1. B for black- dominant2. b for brown- recessiveii. Gene two- determines whether the pigment will be deposited in the hair 1. C for pigment color- dominant2. c for no pigment color- recessiveII. Polygenic Inheritancea. Quantitative traits- vary in the population along a continuumb. Usually indicates polygenic inheritance- additive effect of two or more genes on asingle phenotypei. Skin color & height are examples of polygenic inheritanceIII. Multifactorial Traitsa. Phenotype is affected by environment as well as genotypeb. Hydrangea flowers of the same genotype range from blue-violet to pink, depending on soil acidityc. Nutrition influences heightd. Exercise influences your muscle tonee. Sun influences your skin colorIV. Recessively Inherited Disordersa. Recessively inherited disorders show up only in individuals homozygous for the alleleb. Carriers- heterozygous individuals who carry one recessive allele but are phenotypically normali. Make a sufficient amount of proteinc. Parents are normal- don’t know they are carriers of a disease, baby gets the diseased. Genotypes:i. AA=healthyii. Aa=healthy phenotype (carrier)iii. aa= diseasee. Ex: Tay-Sachs/cystic fibrosis/sickle-cell V. Inbreeding:a. Matings between relatives can increase the probability of the appearance of a genetic diseaseb. Rare disease- unlikely you will meet another carrier for the disease and marry and have childrenc. If it’s a sibling or 1st cousin, very high probability that they are a carrier alsod. Consanguineous matings- inbreedinge. Popular at one time- preserve royal bloodVI. Dominantly Inherited Disordersa. More rare in populations- lethal, most will die before they pass the gene onb. Achondroplasia- form of dwarfism that is lethal when homozygous for the dominant allelec. Genotypes:i. AA=diseaseii. Aa=diseaseiii. aa=healthyd. What if the disorder doesn’t kill you until later?i. Ex. Huntington’s Disease1. Degenerative disease of the nervous system2. No obvious phenotypic effects until about 35 to 40 yrs of age3. Once deterioration of the nervous system begins- irreversible and fatalVII. Multifactorial Disordersa. Many diseases have both genetic and environment componentsb. Little is understood about the genetic contribution to most multifactorial diseases- prevention is keyc. Heart disease, cancer, diabetes, alcoholism, schizophrenia, bipolar disorderd. Exercise, diet, smokingVIII. Applying Mendelian Genetics to Human Inheritancea. We produce too few offspring for significant resultsb. Collect family history for a particular trait- make a pedigree or family treeIX. Dominant/Recessive Inheritancea. Dominant trait- if you have it, one of your parents must express iti. Both parents can have a dominant trait and you don’t, they would be heterozygous 1. Ww + Ww = wwb. Recessive trait- if you have it, neither parents have to have it- heterozygousX. Pedigree Analysisa. Pedigrees- used to make predictions about future offspringb. We can use the multiplication and addition rules to predict the probability of specific phenotypesc. Pedigree characteristics:i. Male-squareii. Female-circleiii. Shaded-if you have