An Example Gel from the "Human SNP Determination" Lab Activity

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The image below shows results for a person heterozygous for the SNP. The control lanes contain PCR product for sterile water, and show no evidence of primer dimerization interfering with gel interpretation. Template A and template B are replicate PCR reactions of the same sample DNA; the 1 microliter designation refers to the amount of template DNA used in the PCR reaction (total reactiion volume of 25 microliters). The lanes with +Hpa II contain samples which were digested with that restriction enzyme after the PCR was performed. With this primer pair, the total length of DNA amplified is 311 base pairs. When cut with Hpa II, the G-SNP should be cut (between base pair 94 and base pair 95), but the A-SNP should not; the results shown are for a heterozygote, which explains the presence of three bands. Fragment sizes for the marker lane DNA are shown on the left side of the gel in base pairs. The numbers on the right side of the gel represnet the expected sizes based on the location of the SNP and the size of the uncut fragment; they seem to agree with the marker lane sizes generally.