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Mendelian Genetics
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Chromatin in a Normal Cell (one length from each parent)
Allele A version of a gene Dominant Allele that may mask the presence of another Recessive Allele that may be masked by another Heterozygous The 2 alleles are different Homozygous The 2 alleles are identical F Free f Attached Earlobe Gene a Albino Melanin Gene a albino P Extra Fingers Polydactyly Gene ♂ ♀
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Chromatin in a Normal Cell (one length from each parent)
Genotype The set of alleles an organism possesses Phenotype The genetic outcome resulting from the genotype F Free f attached Earlobe Gene a albino Melanin Gene a albino P Extra Fingers Polydactyly Gene ♂ ♀
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Inheritance f F f F F f F f
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Exact copies Pure bred parents PP x pp
What will the F1 offspring look like? Phenotype = 100% Purple Genotype = 100% Heterozygous P p What will the F2 offspring look like? Phenotype = 75% Purple 25% white Genotype = 100% Homo. Dominant, 50% Hetero., 25% Homo. Recessive
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Dihybrid Cross GgYy GY Gy gY gy GY PHENOTYPE G-Y- : 9 G-yy : 3
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Law of segregation: two alleles for a trait separate when gametes are formed Law of Independent assortment: Alleles of different genes separate independently of one another during gamete formation
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Codominance Both alleles are detectable in a specimen
Gene: Cattle coat color Alleles CR = red CW = White Genotypes CRCR = red coat CWCW = white coat CRCW = roan coat
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Multiple Alleles More than two alleles exist for a gene
Human Blood Type IA = Type A carbs on RBC surface IB = Type B carbs on RBC surface i = Neither type on RBC surface
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Multiple Alleles Blood Type Genotype Antibodies Universal Acceptor
Universal Donor
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Linked Genes
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Human Genetics
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Dominance Brown over Blue over Green Polygenic Chrom.15 Chrom.19
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Sex linked: traits are tied to X or Y
Xr XR Y XR Y XR XR Xr XR Y XR XR XR XR Xr Y XR Xr Xr XR Xr XR Y
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Sex linked: traits are tied to X or Y
Color blindness:males Recessive x linked Abnormal production of pigment(protein) Does not absorb red green light Y Xr XR Y XR Y XR XR Xr XR Y XR XR XR XR Xr Y XR Xr Xr XR Xr XR Y
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Sex influenced Trait not tied to sex chromosome
Autosomal chromosome produces protein which affects the production of other proteins. Testosterone affects the production and location of hair in males.
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Patterns of Inheritance
Polygenic: Eye color, skin color, height Complex characters: Skin color=sun, Multiple alleles: Blood type Incomplete Dominance: Red x White= Pink X-linked: Color blindness, fruit fly eyes Sex influenced: Male pattern baldness Single alleles: Huntington’s disease,
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