Answer: Doubly charged zwitterions.
- A Neutral non-polar molecules
- B Doubly charged zwitterions
- C Purely negative ions
- D Purely positive ions
Correct answer: B. Doubly charged zwitterions
Explanation: At physiological pH an amino acid carries both a positive (-NH<sub>3</sub><sup>+</sup>) and a negative (-COO<sup>-</sup>) charge - a zwitterion - so it can act as acid or base.
As substrate concentration rises, reaction rate increases steeply at first, then plateaus at Vmax once every enzyme molecule is working at full capacity; Km is the substrate concentration giving half-maximal rate, and a LOWER Km means the enzyme reaches that rate with less substrate (higher affinity).
Concept context
Carbohydrates, proteins, lipids, nucleic acids, and enzyme kinetics. Essential foundation for understanding metabolism.