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67 Cards in this Set
- Front
- Back
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Genetics
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analysis of inheritance patterns to identify and characterize genes
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Genes
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biological factors that induce specific traits
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Alleles
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Alternate forms of a given gene inherited from different parents
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Locus
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location of chomosome often used to refer to gene at that site
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Independent Assortment
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inheritance of alleles at one locus do not influence inheritance at other loci
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Autosomal
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any gene not located on C, not associated with X
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F1 gametes
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independent assortment
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Genotype of F1 gametes
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1:2:1:2:4:2:1:2:1
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Phenotype of F1 gametes
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9:3:3:1
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9/16
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Dominant for both loci
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3/16
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Dominant for 1st loci recessive for 2nd
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1/16
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recessive for both loci
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Cross a hetero/homo Dominant with _________ to figure out genotype
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homozygous recessive
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Complementation asks
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2 mutants w same phenotype made by mutations on same gene or seperate genes
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Mutations in dif genes are complmentary bc
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F1 are wild type heterozygous
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non-Mendelian inheritance
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semidominance, codominance, polygenic inheritance, epistasis, X-linkage, sex-influences inhertiance, linkage
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Semidominance
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partial or incomplete dominance, different alleles for a particular gene have equal effects...heterozygotes= intermed phenotype
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Heterozygouse snapdragon flowers
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pink
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Phenotype and genotype ratios in semiodominant
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the same 1:2:1
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Codominance
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different alleles for a gene that impart independent effects on phenotype (blood types) but A/B codom neither is dom to each other
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Polygenic Inheritance
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multiple genes influencing same trait
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Epistasis
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gene to mask phenotype of another gene at another locus, gene supressing the phenotype of a totally diff gene
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Gene masking phenotype
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Supressor
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Supressed gene
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hypostatic
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More males than females affects think
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colorblind!
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Xinactivation
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inactive one X chromosome in each blastomere, inactivated X become condensed known as Barr bodies
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Barr body creation called
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dosage compensation
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X chromosome inactivation happens in
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64 cell stage early in embryogenesis
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Women are
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genetic mosaics
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LInkage
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2 genes so close they segragate together during inheritance
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Linkage goes against
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independent assortment
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If alleles for 2 genes on same homolog are both dominant or both recessive they are in
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cis conformation
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If dom and recessive on one homology and recessive dom on another homolog they are in
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trans conformation
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If loci are farther apart then
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greater chance for crossing over
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Recombinant frequency is proportional to
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distance between loci
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Genes are linked if
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the numbers are different for genotypes
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Recombinant type progeny
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infrequenct crossovers between linked genes
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Non-recombinant progeny is referred to as
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parental type progeny resemble same conformation
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Map units
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percent recombination between 2 loci
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Max number of map units between genes
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50
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If distance is greater than 50
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equal chance for having an equal or odd number of crossovers between loci...so can same change to produce parental genotype or recombinants
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Genes 50 MU apart or greater are not
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linked
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Monozygotic twins
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develop from same zygot 100%
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Dizygotic
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2 diff zygotes..50%
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Multifactorial traits
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multiple factors both genetic and environmental (body weight)
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Polygenic inheritance
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for a trait to be controlled by multiple genes
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polymorphism
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multiple alleles in a populartion for a gene
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heritability
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estimate how much genetics contributes to a given trait
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quantitiative multifactorial traits
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can be assigned a numerical value
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qualititative multifactorial traits
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cannot be assigned a numerical value either occur or not at all, all or NONE
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Cases at extreme tails of bel curve happen to be influences by
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high proportion of factors (inherited genes and environmental conditions) pushing them to extreme
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qualititative examples
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heart attack, stroke, cancer, schizo, manic-depression, cleft palate, neural tube defcts, pyloric stenosis
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qualitiative traits are plotted as
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chance of manifesting the trait
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threshold point
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where chances for developing cancer are so high it will occur during the persons life
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Hardy Weinberg Equilibrium
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genes and alleles are distributed through a population, model assumes that the distribution, frequency of each allele, is a steady state
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p
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frequency of most abundant allele in populatoin
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q
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lower allelic frequency
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p^2
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frequency of nomral individuals usualy homozygous dominant
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2pq
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heterozygous frequency, carrier frequency
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q^2
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affected frequency, homozygous recessive= incidence
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p and q are
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allelic frequencies
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p^2, q^2, 2pq are
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genotypic frequencies
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primary assumption in hardy-weinberg
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population at equilibrium means gene frequencies are constant
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4 mechanisms for changing gene frequencies (secondary assumptions)
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mutatoin, genetic drift, migratoin, selection
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Fitness
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ability to pass geens onto next generation NOT the ability to survive
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CF recessive allele (q) frequency is
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.045 or 1/22
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Chance child is homozygous for mutates allel (.045) ^2
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.002
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