Which statement best explains why correct protein folding is critical for protein function and cellular health?

• A. A protein’s three-dimensional fold positions key side chains to form specific binding and catalytic sites; misfolding can cause loss of function and aggregation that damages cells.
• B. Correct folding is critical because only folded proteins can be translated by ribosomes; unfolded polypeptides cannot be synthesized.
• C. Correct folding is critical because it prevents peptide bond hydrolysis; misfolded proteins rapidly break down into free amino acids without enzymes.
• D. Correct folding is critical because it determines the amino acid sequence of the protein; misfolding changes the primary structure and therefore the gene’s coding sequence.

Answer: (A)

Verified step by step guidance

1. Understand that protein function is highly dependent on its three-dimensional structure, which is determined by the folding of the polypeptide chain.
2. Recognize that the folding process positions specific amino acid side chains in precise locations, enabling the formation of active sites for binding substrates or catalyzing reactions.
3. Consider that misfolded proteins often lose their functional shape, leading to loss of biological activity and sometimes forming aggregates that can be toxic to cells.
4. Evaluate the incorrect options by recalling that protein folding does not affect the amino acid sequence (primary structure), nor does it influence the process of translation or directly prevent peptide bond hydrolysis.
5. Conclude that the best explanation is that correct folding is essential because it creates the functional three-dimensional structure necessary for protein activity and cellular health.