Biotechnology

A researcher used polymerase chain reaction (PCR) to test four individual diploid nematodes for the presence of a mutation in Gene Y. The researcher designed the reaction so that the DNA fragments amplified from wild type and mutant alleles are 350 and 250 base pairs long, respectively.

To identify the genotypes of the individual nematodes, the researcher visualized each PCR result by gel electrophoresis (Figure 1).

Figure 1. Gel electrophoresis of Gene Y PCRs in nematodes. The first four lanes contain the PCR product from individual nematodes A-D. Lane 5 contains a DNA ladder for size comparison. The size of each band in the ladder is labeled (bp = base pairs).