Final answer:
A chaperone is a protein that assists with the proper folding of other polypeptides, preventing them from aggregating and helping maintain proper functionality even under abnormal conditions like extreme temperatures or incorrect pH levels.
Step-by-step explanation:
A protein that assists with the proper folding of other polypeptides is a chaperone. Chaperones are crucial in ensuring that proteins fold correctly, which is essential for their function. These helper molecules associate with the target protein during the folding process, preventing aggregation of the polypeptides that would otherwise lead to a dysfunctional protein structure. Once the protein is properly folded, the chaperone dissociates from it.
These chaperones are especially important in conditions of abnormal temperature or pH which can interfere with protein folding. Without these critical molecules, even proteins that are properly specified by their corresponding mRNA can become dysfunctional. It is essential to distinguish chaperones from other molecules like enzymes, hormones, and antibodies since their primary role is to assist in protein folding, not to catalyze reactions or to act as signaling or defensive compounds.