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Chapter 4 - BB (1)

Size weight and growth rate as heterosis is different

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Unformatted text preview: quantitative traits such Heterosis as size, weight and growth rate as Heterosis is different from overdominance, because it Heterosis typically involves many genes typically Multiple Alleles Multiple Many genes have multiple alleles Many multiple – Three or more different alleles that are different from each Three other. other. An interesting example is coat color in An rabbits rabbits – Four different alleles C (full coat color) cch (chinchilla pattern of coat color) color) – Partial defect in Partial pigmentation pigmentation ch (himalayan pattern of coat color) color) – Pigmentation in only certain Pigmentation parts of the body c (albino) (albino) – Lack of pigmentation The ABO blood group provides another example of multiple alleles The ABO It is determined by the type of antigen present on the surface of red blood cells – Antigens are substances that are recognized by antibodies produced by the Antigens immune system immune – Antigen A, which is controlled by allele IA Antigen – Antigen B, which is controlled by allele IB Antigen – Antigen O, which is controlled by allele i Antigen X-linked Genes males and females differ in their sex chromosome composition – Certain traits - genes on the sex chromosomes – A pedigree for an X-linked disease shows mostly males affected with pedigree their mothers as carriers their Duchenne Muscular dystrophy Sex and Traits Sex Chromosomes: X- linked XY-linked - holandric Y-linked Pseudoautosomal inheritance Pseudoautosomal The inheritance pattern of certain traits is The governed by the sex of the individual governed two main types – Sex-influenced Sex-influenced – Sex-limited Sex influenced Traits Traits where an allele is dominant in one sex but recessive in Traits the opposite sex the – Thus, sex influence is a phenomenon of heterozygotes Pattern baldness in humans – Caused by an autosomal...
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