Biology 1001A Study Guide - Final Guide: Species Complex, Ordovician, Fetus
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10 Sep 2013
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Pre-lecture: strategy to distinguish between a phenotype that results from codominance relative to incomplete dominance. Incomplete dominance: the effects of recessive alleles can be detected to some extent in heterozygotes. White and red phonotypes in flowers create pink flowers. Codominance: alleles have approximately equal effects in individuals, making the two alleles equally detectable in heterozygotes. White and red phenotypes in flowers create spotted flowers with both phenotypes expressed: characteristics that identify a pleiotropic allele. Pleiotropy: when a single gene effects more than one characteristic. Example: sickle cell disease is caused by a recessive allele of a single gene that affects hemoglobin structure and function. However, the altered hemoglobin protein, the primary phenotypic change of the sickle cell mutation leads to blood vessel blockage, which can damage many tissues and organs in the body and thus affect many body functions, producing wide-ranging symptoms.