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PATTERNS OF HEREDITY. CHP. 10. INCOMPLETE DOMINANCE . An individual displays a trait that is intermediate between the two parents. Neither allele is completely dominant Ex: red vs. white = pink Hair texture: straight vs. curly = wavy. CODOMINANCE. Equal expression of both alleles
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PATTERNS OF HEREDITY CHP. 10
INCOMPLETE DOMINANCE • An individual displays a trait that is intermediate between the two parents. • Neither allele is completely dominant • Ex: red vs. white = pink • Hair texture: straight vs. curly = wavy
CODOMINANCE • Equal expression of both alleles • Ex: Type AB blood
POLYGENIC INHERITANCE • Inheritance pattern of a trait that is controlled by 2 or more genes • Can be on the same chromosome or different ones • Ex: eye color, skin color, height
ENVIRONMENTAL INFLUENCES • Internal environment- age, gender can affect gene function, hormones, structural differences • External environment- temperature, nutrition, light, chemicals, infection
SELECTIVE BREEDING • Produces organisms with desired traits (dogs, horses) • Eliminate undesired traits by inbreeding (mating closely related individuals), keeps a pure line • Testcross- cross of an individual of unknown genotype with an individual of known genotype
Carrier- heterozygous, looks like a homozygous dominant individual
HYBRIDS • Mating of closely related species • The offspring are sterile • Rarely happens in nature • Ex: Liger (lion x tiger)
Wolfdog Wolphin
Zeedonkey Grolar bear