Which protein structure forms when functional groups on the outer surface interact via hydrogen bonds, leading to helices or beta-pleated sheets?

Which protein structure forms when functional groups on the outer surface interact via hydrogen bonds, leading to helices or beta-pleated sheets?

• A. Primary structure
• B. Tertiary structure
• C. Secondary structure
• D. Quaternary structure

Answer: (C)

Hydrogen bonding between the backbone C=O and N–H groups along the polypeptide chain creates regular, repeating patterns that fold into helices or beta-pleated sheets. These backbone interactions stabilize specific geometries regardless of side chains, giving rise to secondary structure. This is different from primary structure (the amino acid sequence), tertiary structure (the overall 3D shape including side-chain interactions), and quaternary structure (how multiple chains assemble). The helices and sheets described are classic examples of secondary structure.

Hydrogen bonding between the backbone C=O and N–H groups along the polypeptide chain creates regular, repeating patterns that fold into helices or beta-pleated sheets. These backbone interactions stabilize specific geometries regardless of side chains, giving rise to secondary structure. This is different from primary structure (the amino acid sequence), tertiary structure (the overall 3D shape including side-chain interactions), and quaternary structure (how multiple chains assemble). The helices and sheets described are classic examples of secondary structure.