One role of intracellular protein degradation is to provide what for synthesis of important proteins?

• A. Provides a constant supply of amino acids for synthesis of important proteins.
• B. Increases storage of fat as energy.
• C. Synthesizes carbohydrates directly.
• D. Degrades DNA molecules.

Answer: (A)

Proteins inside cells are constantly turned over, and breaking them down recycles amino acids that become the building blocks for making new proteins. The amino acids released from degraded proteins re-enter the cellular pool and are used by ribosomes to synthesize enzymes, structural proteins, receptors, and other important proteins needed for growth, repair, and normal function. This recycling keeps a steady supply of amino acids available even when dietary intake is limited or during periods of rapid tissue turnover.

This role is distinct from storing fat as energy, directly synthesizing carbohydrates, or degrading DNA, so providing a constant supply of amino acids for protein synthesis is the best fit.