Final answer:
Hydrophobic interactions are one of the primary forces driving the folding of proteins into their tertiary structure, aided by chaperones which ensure the proteins fold correctly without aggregating.
Step-by-step explanation:
One of the primary forces that help proteins fold into their unique 3D structure at the stage known as the tertiary structure are hydrophobic interactions. These interactions involve the amino acid side chains (or R groups) within the protein. Specifically, when protein folding occurs in the watery environment inside cells, the hydrophobic R groups tend to cluster away from the water, leading to the folding of the polypeptide chain. Additionally, there are other interactions that play a role such as ionic bonding, hydrogen bonding, and disulfide linkages that also contribute to this complex folding process.
Folding is critical for a protein's function and sometimes, proteins receive assistance from protein helpers known as chaperones (or chaperonins). These chaperones prevent the aggregation of the polypeptide chains that constitute the protein, guiding them to achieve their proper structure and then disassociate once the folding is complete.