MCQs

Domains are independently folded structural units within one polypeptide.

Burying hydrophobic residues releases ordered water molecules, increasing entropy.

The genetic code in DNA determines the amino acid sequence through transcription and translation.

Branched β-carbon side chains create steric hindrance in α-helices.

Binding of oxygen to one subunit increases affinity of the remaining subunits.

These repetitive sequences allow close packing of antiparallel β-sheets.

The φ (phi) and ψ (psi) angles define backbone conformation in proteins.

The C-peptide connects the A and B chains in proinsulin and is removed to form mature insulin.

Resonance restricts rotation around the peptide bond, making these six atoms coplanar.

Domains are independently folded regions within a single polypeptide and are part of tertiary structure.

The Val-6 substitution creates a hydrophobic patch on deoxyhemoglobin, leading to polymerization and sickling of red blood cells.

The oxidizing environment of the endoplasmic reticulum promotes the formation of disulfide bonds in secreted and membrane proteins.

Protein function depends on proper folding into the native three-dimensional structure.

The heme prosthetic group contains Fe²⁺, which reversibly binds oxygen.

β-sheets are classified according to the orientation of adjacent strands.

Histidine's pKa is close to physiological pH, making it ideal for acid-base catalysis.

Chaperones bind exposed hydrophobic regions of unfolded proteins, preventing aggregation and promoting correct folding.

Heat disrupts weak interactions but usually leaves the covalent peptide backbone intact.

Collagen contains the repeating sequence Gly-X-Y. Glycine occurs every third residue, allowing tight packing of the triple helix.