Biochemistry - MCQ Practice Questions

Denaturation is disruption of non-covalent interactions (hydrogen bonds, hydrophobic interactions, ionic bonds) that maintain higher-order structures. Peptide bonds (primary structure) remain intact. Some proteins can refold (renature) if conditions permit, as demonstrated by Anfinsen's ribonuclease experiments.

Leucine is a nonpolar, hydrophobic amino acid with an isobutyl side chain. Serine and threonine are polar uncharged, while aspartate is acidic and polar.

Collagen triple helix is stabilized by hydrogen bonds between the three polypeptide chains and covalent cross-links (lysine and hydroxylysine residues) between molecules, providing mechanical strength.

LDH catalyzes the interconversion of lactate and pyruvate using NAD+ as an electron acceptor and NADH as an electron donor in the coupled redox reaction.

ER chaperones like BiP (heat shock protein 70) assist in protein folding, prevent aggregation, and aid in proper disulfide bond formation during synthesis.

Peptide bonds form through a condensation reaction between the carboxyl group (-COOH) of one amino acid and the amino group (-NH2) of another, releasing H2O. They are covalent and stable.