Genetic Origins http://www.geneticorigins.org/geneticorigins/pv92/aluframeset.htm 1 of 2 1/24/07 11:51 AM T H E O R Y This experiment examines PV92, a human-specific Alu insertion on chromosome 16. The PV92 genetic system has only two alleles indicating the presence (+) or absence (-) of the Alu transposable element on each of the paired chromosomes. This results in three PV92 genotypes (++, +-, or --). The + and - alleles can be separated by size using gel electrophoresis. Alu elements are classified as SINEs, or Short INterspersed Elements. All Alu s are approximately 300 bp in length and derive their name from a single recognition site for the restriction enzyme Alu I located near the middle of the Alu element. Human chromosomes contain about 1,000,000 Alu copies, which equal 10% of the total genome. Alu elements probably arose from a gene that encodes the RNA component of the signal recognition particle, which labels proteins for export from the cell. Alu
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