Bios 208 1st Edition Lecture 32 Outline of Last Lecture I. Test CrossII. Mendel’s 1st Law of segregationIII. A Dihybrid CrossIV. Law of Independent Assortment: Mendel’s 2nd LawV. Extending Mendelian Genetics for a Single GeneVI. Multiple AllelesVII. EpistasisOutline of Current Lecture I. Nature and Nurture: The Environmental Impact on PhenotypeII. Pedigree AnalysisIII. Recessively Inherited DisordersIV. Dominantly Inherited DisordersV. Huntington’s Disease: A Late-Onset Lethal DiseaseVI. Multifactorial DisordersVII. Genetic Testing and CounselingVIII. Current LectureI. Nature and Nurture: The Environmental Impact on PhenotypeA. Another departure from Mendelian genetics arises when the phenotype for a character depends on environment as well as genotypeB. The norm of reaction is the phenotypic range of a genotype influenced by the environmentC. For example, hydrangea flowers of the same genotype range from blue-violet to pink, depending on soil acidityD. Many human traits follow Mendelian patterns of inheritanceE. Humans are not good subjects for genetic researchF. Generation time is too longG. Parents produce relatively few offspringH. Breeding experiments are unacceptableThese 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. However, basic Mendelian genetics endures as the foundation of human geneticsII. Pedigree AnalysisA. A pedigree is a family tree that describes the interrelationships of parents and children across generationsB. Inheritance patterns of particular traits can be traced and described using pedigreesIII. Recessively Inherited DisordersA. Many genetic disorders are inherited in a recessive mannerB. These range from relatively mild to life threateningC. Heterozygotes (said to have sickle-cell trait) are usually healthy but may suffer some symptomsD. About one out of ten African Americans has sickle cell trait, an unusually high frequency of an allele with detrimental effects in homozygotesE. Heterozygotes are less susceptible to the malaria parasite, so there is an advantage to being heterozygousIV. Dominantly Inherited DisordersA. Some human disorders are caused by dominant allelesB. Dominant alleles that cause a lethal disease are rare and arise by mutationC. Achondroplasia is a form of dwarfism caused by a rare dominant alleleV. Huntington’s Disease: A Late-Onset Lethal DiseaseA. The timing of onset of a disease significantly affects its inheritanceB. Huntington’s disease is a degenerative disease of the nervous systemC. The disease has no obvious phenotypic effects until the individual is about 35 to 40 yearsof ageD. Once the deterioration of the nervous system begins the condition is irreversible and fatalVI. Multifactorial DisordersA. Many diseases, such as heart disease, diabetes, alcoholism, mental illnesses, and cancer have both genetic and environmental componentsB. Little is understood about the genetic contribution to most multifactorial diseasesVII. Genetic Testing and CounselingA. Genetic counselors can provide information to prospective parents concerned about a family history for a specific
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