Introduction to Genetic Analysis 458

Introduction to Genetic Analysis 458 - 44200_14_p451-480...

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457 14.1 Point mutations Wild-type gene mRNA Protein Missense mutation (e.g., G ? C A ? T) Nonsense mutation (e.g., CAA TAA) Frameshift mutation (e.g., +A) Regulatory region mutation NW No mRNA No protein = Mutational site N = Northern blot (RNA) W = Western blot (protein) = Unpredictable migration Figure 14-4 Effects of common mutations. The effects of some common types of mutations at the RNA and protein levels. Mechanisms of point-mutation induction When we examine the array of mutations induced by different mutagens, we see that each mutagen is char- acterized by a distinct mutational specifcity, or “pref- erence,” both for a certain type of mutation (e.g., G·C : A · T transitions) and for certain mutational sites , called hot spots. Such mutational speciFcity was Frst noted at the rII locus of the bacteriophage T4. Mutagens act through at least three different mech- anisms. They can replace a base in the DNA, alter a base so that it speciFcally mispairs with another base, or dam- age
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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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