What does gel electrophoresis primarily separate?

Gel electrophoresis is a laboratory technique primarily used to separate nucleic acids, such as DNA and RNA, as well as proteins based on their size and charge. When it comes to DNA, the method effectively sorts DNA fragments. The gel acts as a molecular sieve, allowing smaller fragments to move faster through the gel matrix than larger ones.

In the context of DNA, the process involves applying an electric current to the gel, which causes the negatively charged DNA fragments to migrate towards the positive electrode. Because smaller fragments can navigate through the gel more easily than larger ones, they travel further in a given amount of time. This size-based separation enables researchers to analyze, compare, and quantify DNA fragments, making it invaluable in various applications such as genetic testing, forensics, and molecular biology research.

While the technique can also be utilized for RNA and proteins, the specific emphasis in the context of this question is on DNA fragments, solidifying the rationale for selecting the option related to DNA size separation.