Introduction to Genetic Analysis 645

Introduction to Genetic Analysis 645 - CHAPTER OVERVIEW U...

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Unformatted text preview: CHAPTER OVERVIEW U ltimately, the goal of genetics is the analysis of the genotypes of organisms. But a genotype can be iden- tifiedand therefore studiedonly through its effect on the phenotype. We recognize two genotypes as differ- ent from each other because the phenotypes of their carriers are different. Basic genetic experiments, then, depend on the existence of a simple relation between genotype and phenotype. That is why studies of DNA sequences are so important, because we can read off the genotype directly. In general, we hope to find a uniquely distinguish- able phenotype for each genotype and only a simple genotype for each phenotype. At worst, when one allele is completely dominant, it may be necessary to perform a simple genetic cross to distinguish the heterozygote from the homozygote. Where possible, geneticists avoid studying genes that have only partial penetrance and in- complete expressivity (see Chapter 6) because of the difficulty of making genetic inferences from such traits.difficulty of making genetic inferences from such traits....
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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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