This experiment examines a human Alu dimorphism at the PV92 locus. A sample of human cells is obtained by saline mouthwash (alternatively DNA may be isolated from hair sheaths). DNA is extracted by boiling with Chelex® resin, which binds contaminating metal ions. Polymerase chain reaction (PCR) is then used to amplify a chromosome region that contains the PV92 Alu dimorphism. The Alu insertion allele (+) is 300 nucleotides longer than the non-insertion allele (–), so the two alleles are readily separated by agarose gel electrophoresis. Each student scores his or her genotype, and the compiled class results are used as a case study in human population genetics. Tools.
