BIOL239 Lecture Notes - Phenylketonuria, Globin, Y Chromosome
13 Sep 2014
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Document Summary
Many human traits run in families: most do not show a simple mendelian pattern of inheritance (ex: hair colour, height) Because most are influenced by more than one gene multifactorial. Most confirmed single-gene traits in people are relatively rare, involving abnormalities that are either disabling or life-threatening. Studying family genetic histories or pedigrees gives insight as to how mutant alleles causing abnormalities are inherited: all of the following are examples of monomorphic genes with mutant phenotypes showing pleiotropy. Monomorphic: one gene with many different alleles but there"s only one wild type allele. Ex: for humans, the wild type is the normal one. Pleiotropy: multiple effects of having that particular allele: examples of single-gene traits in humans. Sickle-cell disease: abnormal hemoglobin, sickle-shaped red cells, anemia, blocked circulation, increased resistance to malaria. Tay-sachs disease: missing enzyme; build-up of fatty deposit in brain; build-up destroys nervous development; blindness, paralysis, mental retardation. They are born normal but they go downhill.
