Introduction to Genetic Analysis 527

Introduction to Genetic Analysis 527 - ad leu , 9 must be...

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526 Chapter 16 Dissection of Gene Function but suppressors that can cancel the effects of the muta- tion. Suppressors identify genes whose proteins interact with the original mutation-carrying gene. Mutants for certain types of animal behavior are amenable to selections. An example is the light response of Drosophila. Wild-type flies migrate toward light, and mutants that lack this response can be selected by put- Figure 16-6 Testing strains of Neurospora crassa for auxotrophy and prototrophy. In this example, 20 progeny from a cross ad ± leu ² ³ ad ² ± leu are inoculated on minimal medium (Min) with either adenine (Ad, first ), leucine (Leu, second ), neither (third), or both (fourth). Growth appears as a small circular colony (white in the photograph). Any culture growing on minimal medium must be ad ² ± leu ² , one growing on adenine and no leucine must be leu ² , and one growing on leucine and no adenine must be ad ² . For example, culture 8 must be
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Unformatted text preview: ad leu , 9 must be ad leu, 10 must be ad leu , and 13 must be ad leu . [Anthony Grifths.] Light All migrate toward light Wild type Random migration Light Phototaxis mutant Figure 16-7 Selection for behavioral mutants in Drosophila. A T-maze for identifying mutants that are unable to orient and travel toward light. Wild-type ies display positive phototaxis, and all accumulate on the illuminated end of the T-maze. Phototaxis-defective mutants go to either the light or the dark end of the T-maze with equal probability. ting the ies into a T-maze in which one arm of the maze is illuminated and the other is in the dark (Figure 16-7). MESSAGE Genetic selections resolve the mutant and wild-type states by killing or inhibiting the wild types, allowing the easy recovery of a large number of mutants. 44200_16p521-544 3/17/04 9:11 AM Page 526...
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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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