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COMPLEX PATTERNS OF HEREDITY

COMPLEX PATTERNS OF HEREDITY. Polygenic Traits : traits influenced by several genes ex: human eye color, height, weight, hair color. Incomplete Dominance – a trait that is intermediate between the two parents

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COMPLEX PATTERNS OF HEREDITY

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  1. COMPLEX PATTERNS OF HEREDITY Polygenic Traits: traits influenced by several genes ex: human eye color, height, weight, hair color

  2. Incomplete Dominance – a trait that is intermediate between the two parents ex: snapdragons - red flower is crossed with a white flower and pink flowers are produced RR – red Rr – pink rr – white ex: in humans straight hair crossed with curly hair may produce wavy hair SS – straight Ss – wavy ss – curly

  3. Incomplete Dominance: Suppose a red flower is crossed with a pink flower. What are the chances the offspring will have red flowers? Pink flowers?White flowers? 50% 0% 50% R R RR R RR r Rr Rr

  4. Codominance – two dominant traits are expressed at the same time ex: a horse with a black coat is crossed with a horse that has a white coat producing a horse that has both a black and white coat BB – black BW – black & white WW - white

  5. Codominance: Suppose a horse with a black coat is crossed with a horse with a white coat. What are the chances the offspring will have a black coat? White coat? Black and white coat? 0% 0% B B 100% BW W BW W BW BW

  6. Multiple Alleles – genes with 3 or more alleles ex: 3 alleles – A, B, O 4 blood types – A, B, AB, O *Even for traits controlled by genes with multiple alleles, an individual can have only 2 of the possible alleles.

  7. Blood type inheritance is somewhat complicated, with three forms of the gene (A,B,O), 6 possible genotypes, and 4 possible phenotypes. (A, B, AB, O) • AB • AA- Homozygous A • AO- Heterozygous A • BB- Homozygous B • BO- Heterozygous B • OO

  8. Blood Types: Suppose a woman with blood type AB marries a man who is heterozygous B. What are the chances that their children will have blood type A? blood type B? blood type AB? 25% AB 50% 25% B O BB AB AO BO

  9. Traits Influenced by the Environment: • hydrangea plants:acidic soil – blue flowers basic soil – pink flowers • arctic fox:summer – produces enzymes that make pigments therefore it has a reddish brown coat winter – pigment producing genes do not function therefore the coat of the fox is white

  10. Siamese cats: fur color is influenced by body temperature cold – dark coat warm – light coat • humans:height - influenced by nutrition skin – exposure to the sun

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