What type of bond is directly involved in the formation of an α-helix? a. peptide bonds between amino acid residues b. hydrogen bonds between amino acid residues c. van der Waals interactions between nonpolar residues d. disulfide bonds between cysteine residues

Peptide bonds are covalent bonds that link amino acids together in a protein. They form during a dehydration synthesis reaction, where the carboxyl group of one amino acid reacts with the amino group of another, releasing a molecule of water. While peptide bonds are crucial for the primary structure of proteins, they do not directly stabilize secondary structures like the α-helix.

Hydrogen bonds are weak attractions that occur between a hydrogen atom covalently bonded to an electronegative atom and another electronegative atom. In the context of an α-helix, hydrogen bonds form between the carbonyl oxygen of one amino acid and the amide hydrogen of another, stabilizing the helical structure. This interaction is essential for maintaining the secondary structure of proteins.

Secondary structure refers to the local folded structures that form within a protein due to interactions between the backbone atoms. Common types include α-helices and β-sheets, which are stabilized by hydrogen bonds. Understanding secondary structure is vital for grasping how proteins achieve their functional shapes and how these shapes relate to their biological roles.