What key feature allows DNA fragments to be separated in gel electrophoresis?

The ability to separate DNA fragments during gel electrophoresis fundamentally relies on the size of those fragments. When an electric current is applied to the gel, negatively charged DNA molecules migrate towards the positive electrode. Smaller DNA fragments can navigate through the pores of the gel more easily and therefore travel faster and further than larger fragments. This differential movement based on size allows for the effective separation of DNA fragments, enabling researchers to analyze them based on their lengths.

Factors like pH level and agarose concentration can influence the separation process, but the primary mechanism driving this separation is the size of the fragments themselves. Temperature may affect the viscosity of the gel but does not play a direct role in the fundamental separation of DNA fragments by size during the electrophoresis process.