Biophysics of Macromolecules – MCQs 50 Score: 0 Attempted: 0/50 Subscribe 1. The primary structure of a protein refers to: (A) 3D conformation (B) Sequence of amino acids (C) Hydrogen bonding patterns (D) Subunit organization 2. DNA double helix stability is mainly due to: (A) Covalent bonds between bases (B) Hydrogen bonding and base stacking (C) Ionic bonds only (D) Van der Waals interactions only 3. The α-helix is stabilized by: (A) Hydrogen bonds between backbone atoms (B) Ionic bonds between R-groups (C) Base pairing (D) Disulfide linkages 4. β-sheets in proteins are stabilized by: (A) Hydrogen bonds between adjacent polypeptide strands (B) Hydrophobic interactions (C) Covalent bonds (D) Salt bridges 5. The quaternary structure of a protein refers to: (A) Subunit organization (B) Secondary structure (C) Covalent modifications (D) Primary sequence 6. Protein folding is often guided by: (A) Hydrophobic interactions (B) Gravitational forces (C) Base pairing (D) External pressure 7. RNA secondary structures are stabilized by: (A) Base pairing and stacking interactions (B) Disulfide bonds (C) Metal ions only (D) Covalent base cross-links 8. Which technique is most common for determining 3D structure of macromolecules? (A) X-ray crystallography (B) SDS-PAGE (C) Gel electrophoresis (D) Spectrophotometry 9. Circular dichroism spectroscopy is mainly used to study: (A) Protein secondary structure (B) Protein subunit assembly (C) Gene expression (D) DNA replication 10. The Ramachandran plot shows allowed regions of: (A) Dihedral angles (φ and ψ) of amino acids (B) Base pairing angles of DNA (C) ATP hydrolysis pathways (D) Hydrogen bond strengths 11. Molecular chaperones assist in: (A) Protein folding (B) Protein degradation (C) Protein secretion only (D) DNA synthesis 12. Denaturation of proteins involves: (A) Loss of secondary, tertiary, and quaternary structure (B) Breaking peptide bonds (C) Breaking covalent bonds only (D) DNA synthesis 13. DNA melting temperature (Tm) increases with: (A) Higher GC content (B) Higher AT content (C) Lower GC content (D) Increased mismatches 14. Nucleic acids absorb UV light strongly at: (A) 260 nm (B) 280 nm (C) 340 nm (D) 400 nm 15. Proteins absorb UV light strongly at: (A) 280 nm due to aromatic residues (B) 260 nm due to peptide bonds (C) 350 nm due to hydrophobic cores (D) 450 nm due to cofactors 16. Hydrophobic collapse in protein folding refers to: (A) Burial of nonpolar residues inside (B) Loss of hydrogen bonding (C) Loss of ionic interactions (D) Denaturation 17. The B-form of DNA is: (A) Right-handed helix with ~10 bp/turn (B) Left-handed helix with ~12 bp/turn (C) Right-handed helix with ~8 bp/turn (D) Non-helical structure 18. The Z-form of DNA is: (A) Left-handed helix (B) Right-handed helix (C) Triple helix (D) Non-helical 19. NMR spectroscopy is useful for studying: (A) Proteins in solution (B) Only crystallized proteins (C) DNA replication rate (D) Enzyme catalysis exclusively 20. Intrinsically disordered proteins (IDPs) are characterized by: (A) Lack of stable 3D structure (B) Rigid folding (C) High crystallinity (D) Pure α-helical content 21. The Levinthal paradox highlights: (A) Impossibility of random protein folding pathways (B) Energy conservation (C) Base stacking energies (D) Infinite DNA length 22. Protein aggregation is often linked to: (A) Misfolding diseases (B) Cell wall synthesis (C) DNA repair (D) ATP synthesis 23. SDS in SDS-PAGE is used to: (A) Denature proteins and give uniform negative charge (B) Stain proteins (C) Catalyze folding (D) Promote crystallization 24. Glycosidic bonds in nucleic acids link: (A) Sugar to base (B) Sugar to phosphate (C) Base to phosphate (D) Base to base 25. The peptide bond has partial double-bond character due to: (A) Resonance (B) Covalent modifications (C) Hydrogen bonding (D) Ionic forces 26. In collagen, the triple helix is stabilized by: (A) Gly–Pro–Hyp repeats (B) Disulfide bonds (C) Hydrophobic collapse (D) DNA binding 27. Nucleosome formation involves: (A) DNA wrapping around histone proteins (B) Protein folding (C) RNA secondary structure (D) Protein–lipid interactions 28. The hydrodynamic radius of macromolecules is measured by: (A) Dynamic light scattering (DLS) (B) X-ray diffraction (C) Circular dichroism (D) Mass spectrometry 29. Single-molecule biophysics often employs: (A) Optical tweezers (B) Gel electrophoresis (C) Ultracentrifugation only (D) Chromatography 30. The cooperative binding of oxygen to hemoglobin is explained by: (A) Allosteric transitions (B) Covalent modifications (C) Non-cooperative processes (D) Linear kinetics 31. Protein domain refers to: (A) Independently folding unit (B) Entire protein (C) A single amino acid (D) A disulfide bond 32. Hydrogen bonds in macromolecules are typically: (A) 2–5 kcal/mol (B) 20–50 kcal/mol (C) 100–200 kcal/mol (D) <1 kcal/mol 33. Ionic interactions in macromolecules are weakened in: (A) High salt concentration (B) Low salt concentration (C) Vacuum (D) Crystalline solids 34. Hydropathy plots are used to predict: (A) Transmembrane segments of proteins (B) DNA replication origins (C) RNA secondary structure (D) ATP hydrolysis rate 35. Urea and guanidinium chloride denature proteins by: (A) Disrupting hydrogen bonds and hydrophobic interactions (B) Breaking peptide bonds (C) Increasing salt bridges (D) Enhancing folding 36. DNA supercoiling is controlled by: (A) Topoisomerases (B) Helicases only (C) Ligases (D) Polymerases 37. RNA tertiary structures often require: (A) Metal ion stabilization (B) Disulfide bonds (C) Hydrophobic cores (D) Histone binding 38. Protein crystallization is essential for: (A) X-ray diffraction studies (B) NMR analysis (C) SDS-PAGE (D) CD spectroscopy 39. The heme group in hemoglobin is an example of a: (A) Prosthetic group (B) Cofactor only (C) Simple amino acid (D) Disulfide bridge 40. Protein secondary structure content is often expressed as: (A) % α-helix, % β-sheet, % random coil (B) Amino acid sequence (C) Molecular weight (D) Binding affinity 41. Amyloid fibrils are associated with: (A) Protein misfolding diseases (B) DNA stability (C) RNA folding (D) Normal enzymatic activity 42. The term “macromolecule” in biology usually refers to: (A) Proteins, nucleic acids, polysaccharides, lipids (B) Only proteins (C) Only nucleic acids (D) Only lipids 43. The ribosome is best described as a: (A) Ribonucleoprotein macromolecular complex (B) Pure protein (C) Pure RNA (D) Lipid aggregate 44. DNA base stacking contributes to: (A) Helix stability via hydrophobic interactions (B) Hydrogen bond formation only (C) Peptide bond resonance (D) Translation fidelity 45. Protein–DNA binding specificity is largely determined by: (A) Hydrogen bonds and shape complementarity (B) Hydrophobic interactions only (C) RNA modifications (D) ATP hydrolysis 46. Enzyme kinetics are influenced by: (A) Macromolecular crowding in cells (B) Gravitational forces (C) External magnetic fields only (D) DNA replication 47. Which method measures molecular mass and shape in solution? (A) Analytical ultracentrifugation (B) Gel electrophoresis (C) SDS-PAGE (D) X-ray diffraction 48. Chaperonins differ from small chaperones by: (A) Forming large complexes that encapsulate proteins (B) Acting only on DNA (C) Breaking peptide bonds (D) Direct RNA synthesis 49. Ribozymes are: (A) RNA molecules with catalytic activity (B) Protein enzymes (C) Lipid catalysts (D) DNA-binding proteins 50. 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