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1.1 Isolation, Separation & Analysis — Test 1
Q1. In agarose gel electrophoresis, DNA fragments are separated mainly on the basis of their:✓ Size (length)
Q2. During electrophoresis, DNA migrates towards the:✓ Anode (positive electrode)
Q3. In SDS-PAGE, proteins are separated according to their:✓ Molecular weight (size)
Q4. The role of sodium dodecyl sulphate (SDS) in SDS-PAGE is to:✓ Denature proteins and give them a uniform negative charge
Q5. Isoelectric focusing (IEF) separates proteins on the basis of their:✓ Isoelectric point (pI)
Q6. At its isoelectric point, a protein's net charge is:✓ Zero
Q7. In two-dimensional gel electrophoresis of proteins, the first dimension separates by pI and the second dimension separates by:✓ Molecular weight (SDS-PAGE)
Q8. A Southern blot is used to detect specific sequences of:✓ DNA
Q9. A Northern blot is used to detect:✓ RNA
Q10. A Western blot identifies a specific protein using:✓ An antibody
Q11. To resolve very large DNA molecules (hundreds of kb to Mb), the technique of choice is:✓ Pulsed-field gel electrophoresis
Q12. In a Southern blot, after transfer the target DNA on the membrane is located by:✓ Hybridisation with a labelled complementary probe
Q13. Polyacrylamide gels are preferred over agarose gels when separating:✓ Small DNA fragments and proteins (high resolution)
Q14. A common dye used as a tracking (loading) dye to follow the migration front in electrophoresis is:✓ Bromophenol blue
Q15. Proteins separated on an SDS-PAGE gel are most commonly visualised by staining with:✓ Coomassie Brilliant Blue (or silver stain)
Q16. The purity of a DNA preparation is often assessed from the ratio of absorbance at:✓ 260 nm to 280 nm (A260/A280)
Q17. Nucleic acids absorb ultraviolet light maximally at a wavelength of about:✓ 260 nm
Q18. An absorbance (A260) of 1.0 in a 1 cm path corresponds approximately to a double-stranded DNA concentration of:✓ 50 µg/ml
Q19. The probe used to detect a target sequence in Southern or Northern blotting is best described as:✓ A labelled, single-stranded nucleic acid complementary to the target
Q20. Match each blotting technique with the molecule it detects and select the correct option.✓ A-iii, B-iv, C-i, D-ii