MDCAT Chemistry MCQ #4856

At a specific pH known as the isoelectric point, an amino acid exists as a zwitterion. Which functional groups carry the charges in this state?

MDCAT Chemistry MCQ #4856

  1. Question 1

    Q1. At a specific pH known as the isoelectric point, an amino acid exists as a zwitterion. Which functional groups carry the charges in this state?

    • A) COO+ and NH3-
    • B) COO- and NH3+
    • C) COOH and NH2
    • D) COO- and NH2

    Answer: COO- and NH3+

    Explanation: The carboxyl group loses a proton and the amino group gains one; COO+ is chemically impossible and a common distractor.