What is the main purpose of gel electrophoresis in molecular biology?

The main purpose of gel electrophoresis in molecular biology is to separate biological molecules, such as DNA, RNA, or proteins, based on their size and charge. This technique utilizes an electric field to push molecules through a gel matrix, allowing smaller molecules to move faster and further than larger ones. The gel acts as a sieve, effectively sorting the molecules by size, while the charge enables movement toward the electrode of opposite polarity. This separation is critical for various applications, including DNA fragment analysis, sequencing, and protein characterization, as it helps researchers identify and quantify different molecules in a sample.

The other options do not accurately represent the primary function of gel electrophoresis. Amplifying DNA sequences typically relies on techniques like PCR (Polymerase Chain Reaction), while creating chemical modifications is associated with processes like methylation or labeling. Visualizing genes directly would involve techniques such as in situ hybridization or reporter assays, which serve different purposes than the separation function provided by gel electrophoresis.