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CSU ANTH 120 - Genetic Traits

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ANTH 120 1st Edition Lecture 6Outline of Last Lecture II. Cell DivisionIII. Mitosis And MeiosisIV. Genetic TerminologyV. Mendelian Laws of Inheritancea. Law of Segregationb. Law of Independent AssortmentOutline of Current Lecture VI. Non-Mendelian TraitsVII. Forces of Evolution Current LectureMendelian Traits: each gene has a distinct biological effectEx: widows peak, hitchhikers thumb, etc.Non-Mendelian Inheritance any pattern of inheritance in which traits do not segregate in accordance with Mendel’s laws. 1) Incomplete Dominancea. Heterozygote phenotype is intermediate between the dominant and the recessiveb. Ex: Snapdragon flowers, Hair type (curly hair vs. straight hair, one parent with curly and one with straight the child will have 100% chance of getting curly hair)2) Co-dominancea. Both alleles expressed in the phenotypeb. Ex: Alleles for ABO blood types what antigens you have in your red blood cell, 4 possible phenotypes, 3 alleles A, B, O, both A& B alleles are co-dominant)c. Heterozygous (AB) expresses both A & B antigensd. Ex: Sickle-Cell Gene / Sickle-Cell Anemiai. 2 alleles HbA (normal hemoglobin) and HbS (sickle cell hemoglobin)ii. Sickle-cell trait: HbAHbS of hemoglobiniii. Usually symptom free3) Polygenic Inheritancea. Many genes one phenotyleb. Multiple genes with on particular phenotype (effect)c. Ex: Height: range of variation associated with height that are controlled by many different genes and variablesd. Range of variation= Bell Curve 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.e. Ex: Skin Color4) Pleiotrophya. Single gene multiple effectsb. Ex: PKU Allele 5) Sex-Linked Traitsa. X & Y chromosomes i. 23rd pair of chromosomesii. Not homologous (they do not carry the same set of genes)1. X & Y carry different genesiii. Males: XYiv. Females: XXv. Sperm determines the sex of offspringb. X-linked inheritancei. Passed to sons by mothersii. More males expressiii. Example: red-green color blindness1. Hemophelia bleeding disorderExpanded Definition of Evolution:Inherited change in allele frequencies in a population’s gene pool through time.Forces of Evolution1) Natural Selection a. Reproduction of the fittesti. The Peppered Moth2) Mutation a. Spontaneous change in existing genesb. Only source of NEW alleles and genes3) Genetic Drifa. Random change in gene frequency from one generation to the nextb. Greater effect in small populations 4) Gene Flowa. Spread of genetic material between populationsMutation: spontaneous change in existing genes1) Chromosomal 2) Molecular (DNA)- it can happen at any point of cell division - During transcription / translation / replication- From Chemicals or toxins- In gametes can be passed to offspringo Can be good, bad, or neutralo In somatic cells can inhibit functionExamples: 1) INDEL: Insertion / Deletion Eventa. 1 nucleotide has been replaced, deleted or added  “frame shif sequence”b. NON-Synonymous Substitution = change in allele frequencies2) Substitution: same amino acid and same proteinGenetic Drif: random change in gene frequency over timeChange in allele frequency due to CHANCE1) Traits lost or fixed2) Variability in the genetic code is reducedMay occur in endogamous (isolation) groupsTypes: 1) Bottle Neck Effect a. Even reproduces the population to a really small size2) Founder’s Effecta. A few individuals colonize a new areab. Gene variability is reducedc. Example: Amish migrate to Pennsylvania (1744)  Ellis-van-Creveld SyndromeGene Flow (admixture): spread of genetic material between populations1) Migration: influenced by culture and social structure2) Increases genetic variation over timea. Example: blood type distribution across


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