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HUMAN SKIN COLOR

HUMAN SKIN COLOR. A POLYGENIC TRAIT. Polygenic Trait (multiple gene):. Human skin color is an example of a polygenic trait. It is known that at least three or four genes control skin color, and for each of those genes, dark pigment has incomplete dominance over light.

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HUMAN SKIN COLOR

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  1. HUMAN SKIN COLOR A POLYGENIC TRAIT Presented by Steven Agelidis Biology 108

  2. Polygenic Trait (multiple gene): • Human skin color is an example of a polygenic trait. • It is known that at least three or four genes control skin color, and for each of those genes, dark pigment has incomplete dominance over light. • Someone who is AABBCC would have very dark skin. • Someone who is aabbcc would have very light skin. • If they would get married and have children, their children would all have AaBbCcmedium dark skin. • If two of those people would get married and have children, the Punnett square would look like this:

  3. Medium dark MALE X FEMALE Medium dark AaBbCc AaBbCc

  4. AaBbCc X AaBbCc

  5. Polygenic Pigmentation

  6. Phenotype Distribution • Parental Genotypes AaBbCc X AaBbCc Dark skin = ABC = Light skin = abc = • Offspring Phenotype distribution probabilities: 1/64 very dark 6/64 15/64 20/64 medium dark 15/64 6/64 1/64 very light

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