Introduction to Genetic Analysis 620

Introduction to Genetic Analysis 620 - 44200_19_p611-642...

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fragments will migrate at different rates in an elec- trophoretic gel. The individual copies of the repeated se- quence elements are too short to allow distinguishing between, say, 64 and 68 repeats, but size classes that in- clude several repeat numbers ( bins ) can be established, and a population can be assayed for the frequencies of the different classes. Table 19-5 shows the data for two different VNTRs sampled in two American Indian groups from Brazil. In one case, D14S1, the Karitiana are nearly homozygous, whereas the Surui are very variable; in the other case, D14S13, both populations are variable but with different frequency patterns. COMPLETE SEQUENCE VARIATION A ubiquitous form of genetic variation is variation in the nucleotide at a sin- gle position, called a single-nucleotide polymorphism ( SNP ). Studies of variation at the level of single base pairs by DNA sequencing can provide information of two kinds. First, DNA sequence variation can be studied in the protein-coding regions of genes. The sequences of
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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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