Gel electrophoresis separates molecules based on two properties. Which two properties are involved?

Gel electrophoresis separates molecules based on two properties. Which two properties are involved?

• A. Size and charge
• B. Only size
• C. Only charge
• D. Color and brightness

Answer: (A)

Gel electrophoresis separates molecules by how they move through a gel under an electric field, and two properties govern that movement: size and charge. The gel acts as a sieve—the bigger the molecule, the more it is impeded by the pores, so it moves more slowly. At the same time, the electric field pulls charged molecules toward the opposite electrode; molecules with more charge (or higher charge density) will migrate faster. In DNA, every fragment carries a similar amount of negative charge per length, so size differences mainly determine how fast fragments move: smaller pieces travel farther in the same time. Color and brightness don’t affect migration; they’re about visualization after the run.

Gel electrophoresis separates molecules by how they move through a gel under an electric field, and two properties govern that movement: size and charge. The gel acts as a sieve—the bigger the molecule, the more it is impeded by the pores, so it moves more slowly. At the same time, the electric field pulls charged molecules toward the opposite electrode; molecules with more charge (or higher charge density) will migrate faster. In DNA, every fragment carries a similar amount of negative charge per length, so size differences mainly determine how fast fragments move: smaller pieces travel farther in the same time. Color and brightness don’t affect migration; they’re about visualization after the run.