Introduction to Genetic Analysis 130

Introduction to - 44200_04_p115-150 2:20 PM Page 129 4.3 Linkage maps 129 sons for mapping are to understand gene function and gene evolution and

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129 4.3 Linkage maps sons for mapping are to understand gene function and gene evolution, and to facilitate strain building. 1. Gene function. How can knowing the map position of a gene contribute to understanding its function? Essentially map position provides a way of “zeroing in” on a piece of DNA. If the genome of an organism has not been sequenced, the map position can provide a way of physically isolating the gene (this is called positional cloning , described in Chapter 11). Even if the genome has been completely sequenced, the phenotypic impact of most of the genes in the sequence is not understood, and mapping provides a way of correlating the position of an allele of known phenotypic affect with a candidate gene in the genomic sequence. Map position can be important in another way. A gene’s location is sometimes important for gene function because the location can affect the gene’s expression, a phenomenon generally called a “neighborhood effect.” Genes of related function are often clustered next to one another in bacterial chromosomes, generally because they are transcribed as one unit. In eukaryotes, the position of a gene in or near heterochromatin can affect its expression. 2.
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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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