lab 7: plasmid DNA analysis by agarose gel electrophoresis

1. Why does DNA migrate in an electric field?

C. It is negatively charged at physiological pH

2. Why aren’t polyacrylamide gels suitable for large DNA?

B. Pore size too small

3. Agarose is chemically a linear polymer of:

B. Galactopyranose derivatives

4. Effective agarose concentration for nucleic acid separation is:

B. 0.3–2%

5. DNA is visualized in agarose gel using:

C. Ethidium bromide

6. Ethidium bromide fluorescence increases when:

B. It intercalates between DNA bases

7. Under UV light, EtBr-stained DNA bands appear:

C. Orange-red

8. DNA mobility is affected by:

B. Agarose concentration, DNA size, conformation, and buffer ionic strength

9. DNA molecular weight estimation uses:

B. Known DNA size markers

10. Superhelical circular DNA is called:

C. Form I

11. Which DNA form migrates fastest?

B. Supercoiled circular (Form I)

12. Which DNA form migrates slowest?

B. Form II

13. Source of agarose is:

B. Seaweed (red algae)

14. 1% agarose gel is prepared using:

B. 1 g agarose in 100 mL buffer

15. EtBr final concentration in gel is:

B. 0.5 μg/mL

16. Restriction digestion incubation temperature:

B. 37°C

17. Minimum digestion time is:

C. 3.5 hours

18. Loading buffer contains:

B. Sucrose and bromophenol blue

19. Function of sucrose in loading buffer:

B. Adds density to sink sample

20. Bromophenol blue function is:

C. Tracking dye

21. Gel running buffer is:

C. TBE buffer

22. Applied voltage for gel run:

C. 120 V

23. Gel run time until dye front reaches midpoint is:

C. 30–35 min

24. DNA is visualized using:

C. UV illumination

25. Ethidium bromide safety precaution:

B. Wear gloves

26. DNA conformation with intermediate mobility:

C. Form III

27. Plasmid DNA forms seen on gel represent:

B. Different conformations

28. Supercoiled form moves fastest because:

B. Compact structure migrates easily

29. Linear DNA migrates more slowly than supercoiled because:

B. Rod-like shape less compact

30. Purpose of this lab experiment was:

C. To analyze isolated plasmid DNA