What technique is often used to amplify DNA before gel electrophoresis?

The technique commonly used to amplify DNA prior to gel electrophoresis is polymerase chain reaction, known as PCR. This method involves the enzymatic replication of a specific DNA segment, resulting in an exponential increase of that target DNA sequence. By cycling through a series of temperature changes that allow for denaturation, annealing of primers, and extension of new DNA strands, PCR makes it possible to generate millions of copies of a particular DNA fragment quickly and efficiently.

This amplification is critical for gel electrophoresis because it ensures that there is an adequate amount of DNA available to visualize on the gel. The amplified DNA can then be separated based on size, allowing for the analysis of genetic material, detection of mutations, or identification of specific genes.

In contrast, restriction digestion involves cutting DNA at specific sequences, which is not an amplification technique; SDS-PAGE is used for separating proteins, and ELISA tests for proteins or antibodies rather than DNA.