Q.The alpha-helix and the beta-pleated sheet are examples of which level of protein structure, stabilised mainly by hydrogen bonds between backbone -NH and C=O groups?

[!TLDR]

The alpha-helix and beta-pleated sheet, formed by backbone hydrogen bonding, are examples of a protein's seco …

Secondary structure refers to regular, repeating local folding patterns within a polypeptide chain, produced by hydrogen bonds forming between the backbone -NH and C=O groups of nearby amino acids. The alpha-helix (a right-handed coil) and the beta-pleated sheet (extended strands lying side by side) are the two most common secondary-structure motifs. Primary structure is just the linear amino-acid sequence with no folding; tertiary and quaternary structure …

Match "hydrogen bonds between backbone -NH and C=O" specifically to the alpha-helix/beta-sheet seconda …

Confusing secondary structure (backbone hydrogen bonding, alpha-helix/beta-sheet) with tertiary structure (side-c …