What is the primary use of gel electrophoresis?

Gel electrophoresis is primarily used to separate and analyze DNA fragments based on their size and charge. This technique involves applying an electrical current to a gel matrix, which causes the DNA fragments to migrate through the gel. Smaller fragments move faster and travel further than larger ones, allowing for the separation of DNA strands that can then be visualized and analyzed.

This separation is essential in numerous applications, such as genetic fingerprinting, cloning, and analyzing PCR products, which all require an understanding of the size and quantity of DNA fragments.

The other options represent different processes in molecular biology. Replicating DNA involves the action of enzymes like DNA polymerase and is not the focus of gel electrophoresis. Sequencing RNA refers to determining the exact order of nucleotides, which is a different technical procedure that does not involve gel separation as its primary method. Amplifying genetic material, particularly through techniques like PCR (Polymerase Chain Reaction), increases DNA quantities rather than analyzing their structures or sizes. Thus, separating and analyzing DNA fragments is a distinctive feature of gel electrophoresis, making it the correct answer in this context.