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Incomplete Dominance

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Incomplete Dominance. Neither allele is dominant over the other Heterozygous offspring have a phenotype that is somewhere between the two. Incomplete Dominance. Incomplete Dominance. Homozygous red parent: RR crossed with Homozygous white parent: WW RR x WW - PowerPoint PPT Presentation
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  • Incomplete DominanceNeither allele is dominant over the otherHeterozygous offspring have a phenotype that is somewhere between the two.

  • Incomplete Dominance

  • Incomplete DominanceHomozygous red parent: RRcrossed withHomozygous white parent: WW RR x WW yields heterozygous offspring RW that are pink

  • Incomplete Dominance

  • CodominanceBoth alleles contribute to the phenotype

    Heterozygous offspring express both alleles

  • CodominanceX

  • Codominance: A black chicken crossed with a white chicken results in a speckled chicken

  • CODOMINANCE: ABO BLOOD TYPESBlood type depends on the presence or absence of certain carbohydrates on the surface of red blood cells3 alleles are possible:IAIBi

  • ABO BLOOD TYPESIA and IB are codominant to each other when they are paired.

    i allele is recessive to both IA and IB

  • ABO Blood Groups

  • ABO Blood Groups

  • ABO Blood TypesBlood typing is actually far more complicated than A, B, and OABO are the MAJOR antigensThere are also MINOR antigensRh factor: + or -

  • ABO Blood Types

  • ABO Blood Types

  • ABO Blood Types

  • ABO Blood TypesWhy is it important to get the right blood type when getting a transfusion?Transfusion ReactionsImmune system (antibodies) will attack cells that have an antigen that the body doesnt recognize as self

  • Transfusion Reaction

  • Multiple Alleles

    More than 2 possible alleles exist in a population

  • Multiple AllelesCoat color in rabbits: there are at least 4 different allelesC = full color (dominant to all other alleles)c (ch) = chinchillac (h) = himalayanc = albino (recessive to all other alleles)

  • Full color rabbit

  • Chinchilla rabbit: partial defect in pigmentation

  • Himalayan rabbit: color in only certain parts of body

  • Albino rabbit: no color; recessive to all other alleles

  • Polygenic Traits

    Traits that are produced by the interaction of more than one different genes

  • Polygenic InheritanceFor example: coat color in Labrador retrievers is a result of interaction of 2 different genes.

  • Polygenic InheritanceExample: comb shape in chickens is a result of interaction between 2 different genes.

  • X-Linked InheritanceEarly 1900sThomas Morgans fruit fly studies

  • X-Linked Inheritance

  • X-Linked InheritanceMore than 300 human traits are X-linked.Most common X-linked recessive disorders:HemophiliaRed-green colorblindnessDuchenne muscular dystrophyAdrenoleukodystrophy (seen in the movie Lorenzos Oil)

  • BARR BODIESBarr body is found only in femalesIt is a darkly staining area in the nucleus of a cell that represents an inactivated X chromosomeOne X chromosome is randomly inactivated

  • Barr Body

  • Barr BodyDo you see the Barr body?

  • Barr Body: X inactivationCalico catGenerally all femalesHave one X chromosome coding for for gold color, and one X chromosome coding for black colorColor pattern shows how one X chromosome in each cell is randomly inactivated

  • Calico CatThere have been instances of male Calico cats foundHow could this happen?

  • Male Calico cat?HINT: Male calico cats are sterile

  • Male Calico cat?Answer: Male Calico cats have XXY chromosome configurationA Klinefelters cat? Yup, it happens.

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