What happens to a protein when it is denatured under conditions such as heat or extreme pH?

• A. It is converted into a different protein with a new amino acid sequence through rearrangement of peptide bonds without breaking them.
• B. It becomes covalently cross-linked into a new, stable structure that permanently increases its catalytic activity.
• C. It loses its native secondary and tertiary structure (and possibly quaternary structure) due to disruption of noncovalent interactions, often leading to loss of function.
• D. Its primary structure is cleaved into free amino acids by hydrolysis of peptide bonds.

Answer: (C)