Final answer:
The peptide bond is NOT a non-covalent interaction; it is a covalent bond that forms between amino acids in proteins. Other listed options involve non-covalent interactions integral to protein structure and function.
Step-by-step explanation:
The option that is NOT a non-covalent interaction is A. Peptide bond. Peptide bonds are the covalent bonds that link amino acids together into polypeptides and subsequently proteins, contrary to other options listed that involve non-covalent interactions. For example, interactions between phospholipid molecules often involve hydrophobic interactions, which are non-covalent. Interactions that form the secondary structure of proteins, such as hydrogen bonds, are also non-covalent. Lastly, the interaction between K+ ions and the K+ channel typically involves ionic bonding and other non-covalent interactions that help K+ ions pass through the channel.
Options B, C, and D all represent non-covalent interactions that are critical to protein structure and function. Non-covalent interactions include hydrophobic interactions, ionic bonding, hydrogen bonding, dispersion forces, and disulfide linkages, all of which play significant roles in stabilizing the tertiary structure of proteins.