For my biochemistry quiz, I need help.?

These are the major forces that cause polypeptide chains to fold in solution. A number of different amino acid side chains, as well as the C=O and N-H of the polypeptide backbone are able to form hydrogen bonds. It is these bonds that stabilize the secondary structures of alpha helices and beta-sheets. Additionally, dipole-dipole interactions (along with hydrogen bonds) cause polar side chains to be found on the surface of the protein where they can interact nicely with water. Too, many interactions with ligands involve hydrogen bonds and dipole-dipole interactions. London dispersion forces basically account for the "hydrophobic interactions" that cause non-polar side chains to aggregate in the interior of the folded protein as they are repelled by water.