Biology Biotechnology PMDC Conceptual Practice
PMDC Verified Question 13 of 65
In gel electrophoresis, DNA fragments migrate toward the anode because DNA is:
A
Negatively charged
B
Positively charged
C
Neutral in charge
D
Hydrophobic
Tap any option to test your recall and reveal the step-by-step Propolis autopsy.

Propolis Cognitive Error Autopsy

Official Correct Choice:
Option A: Negatively charged
Concept:

Charge-dependent migration of biological macromolecules in an electric field.

Solution:

DNA carries a uniform negative charge due to the phosphate groups (\( \text{PO}_4^{3-} \)) in its sugar-phosphate backbone. When an electric current is applied, DNA migrates toward the positively charged electrode (anode).

Why other options are incorrect:

  • Positively charged: Positively charged molecules would migrate toward the cathode (negative electrode).


  • Neutral in charge: Neutral molecules would not experience directional electromotive force in an electric field.


  • Hydrophobic: DNA is highly hydrophilic due to its polar sugar-phosphate outer surface.

Quality & Fidelity Assurance: Every question on BeambePrep is rigorously curated against the official PMDC syllabus with zero filler, zero out-of-syllabus content, and zero typos. When an authentic past paper originally contained a historical mistake or ambiguity from the examining board (such as UHS or NUMS), BeambePrep faithfully reflects the original paper while detailing the nuance and scientific consensus in the autopsy above.

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