Gel Electrophoresis – Section 1

1. In an SDS-PAGE

A. proteins are denatured by the SDS
B. proteins have the same charge-to-mass ratio
C. smaller proteins migrate more rapidly through the gel
D. all of the above

Correct Answer: D. all of the above

2. Proteins can be visualized directly in gels by

A. staining them with the dye
B. using electron microscope only
C. measuring their molecular weight
D. none of these

Correct Answer: A. staining them with the dye

3. In SDS-PAGE, the protein sample is first

A. treated with a reducing agent and then with anionic detergent followed by fractionation by electrophoresis
B. fractionated by electrophoresis then treated with an oxidizing agent followed by anionic detergent.
C. treated with an oxidizing agent and then with anionic detergent followed by fractionation by electrophoresis
D. none of the above

Correct Answer: A. treated with a reducing agent and then with anionic detergent followed by fractionation by electrophoresis

4. Electrophoresis of histones and myoglobin under non-denaturing conditions (pH = 7.0) results in

A. both proteins migrate to the anode
B. histones migrate to the anode and myoglobin migrates to the cathode
C. histones migrate to the cathode and myoglobin migrates to the anode
D. both proteins migrate to the cathode

Correct Answer: C. histones migrate to the cathode and myoglobin migrates to the anode

5. In isoelectric focusing, proteins are separated on the basis of their

A. relative content of positively charged residue only
B. relative content of negatively charged residue only
C. size
D. relative content of positively and negatively charged residue

Correct Answer: D. relative content of positively and negatively charged residue

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