In gel electrophoresis, DNA fragments are separated primarily by size; which factor most directly influences their rate of movement through the gel?

Prepare for the Biology Marking Period 3 Test. Engage with flashcards and multiple choice questions; each with explanations. Boost your grades!

Multiple Choice

In gel electrophoresis, DNA fragments are separated primarily by size; which factor most directly influences their rate of movement through the gel?

Explanation:
DNA fragments move through a gel mainly because the gel acts as a sieve. DNA’s backbone is uniformly negatively charged, so the charge per length is roughly constant across fragments. The electric field pulls them toward the positive electrode, but the gel’s pore structure presents more friction to larger fragments. Smaller pieces slip through pores with less resistance and thus migrate faster, while larger pieces are slowed down more. That’s why the rate of movement is governed primarily by size. Sequence or GC content don’t noticeably alter mobility under standard gel conditions, and the uniform charge-to-mass ratio across fragments means size is the key factor.

DNA fragments move through a gel mainly because the gel acts as a sieve. DNA’s backbone is uniformly negatively charged, so the charge per length is roughly constant across fragments. The electric field pulls them toward the positive electrode, but the gel’s pore structure presents more friction to larger fragments. Smaller pieces slip through pores with less resistance and thus migrate faster, while larger pieces are slowed down more. That’s why the rate of movement is governed primarily by size. Sequence or GC content don’t noticeably alter mobility under standard gel conditions, and the uniform charge-to-mass ratio across fragments means size is the key factor.

More Multiple Choice Questions
Subscribe

Get the latest from Passetra

You can unsubscribe at any time. Read our privacy policy