試題詳解

40. Which of the following statements about isoelectric point is TRUE?
(A) An isoelectric point is the pH where a molecule has equal negative and positive charges
(B) Proteins have isoelectric points but amino acids do not
(C) Positive charges of a protein increase as pH increases
(D) At the isoelectric point, a molecule moves to the anode in an electric field
(E) Since proteins carry zero charges at isoelectric points, electrophoresis cannot separate different proteins based on isoelectric points