sept 1 - H ERED ITY Some parental traits seem to blend in...

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1 HEREDITY You don’t have to be a scientist to see that physical traits are inherited from parents to offspring. Some parental traits seem to “blend” in the offspring. ( This is usually true for traits that are governed by a large number of genes. ) But blending is an illusion, not a biological reality. Labrador retrievers come in three colors: brown; black; and golden. These colors are determined by two genes, but the genes DO NOT blend when the dogs breed. First, a description of some terms in terms of transmission genetics , not molecular genetics Gene - the code for a particular trait, the unit of heredity that occurs at a particular chromosome locus. Gene locus - place on the chromosome for a particular gene Alleles - alternate versions of a gene that can occur at a particular gene locus; differences in alleles account for different phenotypes Genotype - the alleles present in a given individual at a locus Phenotype - the observable trait in a given individual From Campbel Mendel’s pioneer work in genetics established some important postulates: (Klug p. 42) 1. Genetic factors occur in pairs. (paired factors) 2. When two different factors are present
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This note was uploaded on 02/22/2010 for the course BIO 51980 taught by Professor Buskirk during the Fall '06 term at University of Texas at Austin.

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sept 1 - H ERED ITY Some parental traits seem to blend in...

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