MCAT Biochemistry Question 32: Answer and Explanation

Home > MCAT Test > MCAT biochemistry practice tests

Test Information

Question: 32

2. What is the function of sodium dodecyl sulfate (SDS) in SDS-PAGE?

  • A. SDS stabilizes the gel matrix, improving resolution during electrophoresis.
  • B. SDS solubilizes proteins to give them uniformly negative charges, so the separation is based purely on size.
  • C. SDS raises the pH of the gel, separating multiunit proteins into individual subunits.
  • D. SDS solubilizes proteins to give them uniformly positive charges, so separation is based purely on pH.

Correct Answer: B

Explanation:

Sodium dodecyl sulfate is a detergent and will digest proteins to form micelles with uniform negative charges. Because the protein is sequestered within the micelle, other factors such as charge of the protein and shape have minimal roles during separation. In essence, the protein micelles can be modeled as being spheres, dependent only on size.

Previous       Next