Introduction to Genetic Analysis 524

Introduction to Genetic Analysis 524 - 44200_16p521-544...

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523 16.1 Forward genetics 16.1 Forward genetics Typically, forward genetics starts with the wild-type genome, mutates it randomly with a mutagen, and sys- tematically surveys it for mutations that share some common phenotype. This procedure is sometimes called a mutant hunt . Ideally, we will identify mutations in lit- erally all the genes in the genome that can be mutated to a state that confers that particular phenotype. Then we can say that we have saturated the genome for muta- tions of that class. In reality, it is very difFcult to achieve total saturation—for several reasons. Typically a muta- gen has a low, more or less equivalent probability of mu- tating any region of the genome. However, the sizes of genes within a species can vary considerably. The larger the size of the gene, the greater is the mutagen’s target, and the more likely it is that a mutation will be pro- duced in it. ±urthermore, because mutations are often pleiotropic (have numerous effects on the phenotype), it is possible that a mutation’s more severe effect—such as causing death during development—might mask its milder manifestations, such as altering adult hair color.
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This note was uploaded on 01/10/2011 for the course BIOL BIOL taught by Professor Johnson during the Spring '08 term at Aberystwyth University.

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