06BIS101S2013DomRecLect6

Normal function is indicated by a threshold for the

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Unformatted text preview: mutations (1 and 2) relative to wild type (wt). Notice that there Drosophilia is a threshold of enzyme (xanthine dehydrogenase) needed to produce red eyes (wt). Since heterozygotes of the two mutations exceed the threshold, they are recessive to the dominant wild type allele. dominant 02/12/14 BIS101­001, Spring 2013—Genes and Gene Expression, R.L. Rodriguez ©2013 BIS101­001, Spring 2013—Genes and Gene Expression, R.L. Rodriguez 21 Molecular Basis of Dominance ­ The amount of product made by an enzyme is The generally proportional to the amount of enzyme present. ­ Normal function is indicated by a threshold for the Normal level of product needed to produce a normal phenotype. ­ When there is an excess of the enzyme, however, When the amount of product made follows the law of diminishing return. As shown in the next figure, some genetic diseases can be recessive (e.g., alkaptonuria) while others can be dominant. 02/12/14 BIS101­001, Spring 2013—Genes and Gene Expression, R.L. Rodriguez ©2013 BIS101­001, Spring 2013—Genes and Gene Expression, R.L. Rodriguez 22 Effects of Gene...
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This note was uploaded on 02/12/2014 for the course BIS 101 taught by Professor Simonchan during the Spring '08 term at UC Davis.

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