What is gel electrophoresis primarily used for?

Gel electrophoresis is a powerful laboratory technique primarily used to separate macromolecules such as DNA, RNA, and proteins based on their size and charge. In this process, a gel matrix—commonly composed of agarose or polyacrylamide—is used as a medium through which the samples migrate when an electric current is applied. The negatively charged molecules, like DNA and RNA, move towards the positive electrode, and smaller fragments travel faster and further through the gel pores than larger fragments.

This separation allows researchers to analyze the size of the molecules or assess the purity of the sample. For instance, in DNA analysis, researchers can determine the size of DNA fragments that have been digested with restriction enzymes, or visualize amplified products from PCR. Understanding the mobility of proteins in relation to their size and charge is also fundamental in studies of protein expression and purification.

The other options, while related to molecular biology, do not accurately capture the primary purpose of gel electrophoresis. Amplifying RNA pertains to techniques like reverse transcription PCR, analyzing gene expression generally involves techniques like qPCR or microarrays, and enhancing protein visibility is often associated with staining techniques or Western blotting rather than the separation process itself.