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1.1 Isolation, Separation & Analysis — Test 2
Q1. Gel-filtration (size-exclusion) chromatography separates molecules on the basis of their:✓ Size (molecular weight)
Q2. Ion-exchange chromatography separates proteins according to their:✓ Net surface charge
Q3. Affinity chromatography purifies a molecule based on its:✓ Specific binding to an immobilised ligand
Q4. A recombinant protein engineered with a histidine (His) tag is most conveniently purified by:✓ Nickel (Ni-NTA) affinity chromatography
Q5. Differential centrifugation separates cell components mainly by differences in their:✓ Size and density (sequential pelleting)
Q6. A caesium chloride (CsCl) density-gradient centrifugation separates DNA on the basis of its:✓ Buoyant density
Q7. The sedimentation coefficient of a particle is expressed in:✓ Svedberg (S) units
Q8. High-performance liquid chromatography (HPLC) achieves high resolution mainly because it uses:✓ Fine column packing under high pressure
Q9. The Bradford and Lowry assays are used to determine the concentration of:✓ Protein
Q10. Protein absorbance at 280 nm, used for quantification, is mainly due to the amino acids:✓ Tryptophan and tyrosine
Q11. According to the Beer-Lambert law, the absorbance of a solution is directly proportional to the:✓ Concentration and path length
Q12. Dialysis is commonly used in protein purification to:✓ Remove small molecules / exchange buffer
Q13. An ultracentrifuge is distinguished from an ordinary centrifuge by its ability to:✓ Generate very high speeds to sediment macromolecules
Q14. The pure dsDNA A260/A280 ratio of about 1.8 indicates that the sample is:✓ Relatively free of protein contamination
Q15. In column chromatography, the mobile phase is the:✓ Solvent that moves through the column
Q16. To separate intact organelles such as mitochondria from a cell homogenate, the preferred method is:✓ Centrifugation
Q17. A spectrophotometer measures the amount of light that a sample:✓ Absorbs (or transmits) at a given wavelength
Q18. Reverse-phase chromatography separates molecules mainly according to their:✓ Hydrophobicity
Q19. The first step in isolating genomic DNA from cells is usually to:✓ Lyse the cells to release their contents
Q20. Match each separation technique with the property it exploits and select the correct option.✓ A-iii, B-i, C-ii, D-iv