Which technique separates proteins according to size?

A. Treatment with restriction endonucleases
B. PCR
C. Gel electrophoresis
D. DNA profiling

C

Despite some complaints, this question was well answered by good candidates. In general, proteins are separated using a polyacrylamide gel. The SDS-page method is one of the most popular in molecular biology procedures. In this case, proteins are previously denatured. SDS molecules bind to unfolded proteins in large excess, providing extra negative charges to the molecules. Therefore, upon SDS-treatment, the specific charge (the charge-to-mass ratio) of different proteins will become roughly identical.