Question

Which of the following is not true about gel electrophoresis?

• A. Gel electrophoresis can be used to separate nucleic acids or proteins.
• B. Agarose and polyacrylamide are routinely used in gel electrophoresis.
• C. In gel electrophoresis of DNA, the digested DNA fragments move toward the negative electrode of the tank.
• D. In gel electrophoresis of DNA, ethidium bromide, a DNA binding dye, is used to locate the DNA fragments of interest under UV light.

Hint:

Remember that DNA is a nucleic \textbf{acid}. Acids donate protons, leaving a negative charge. In electrophoresis, opposites attract, so negative DNA migrates to the positive pole (anode).

Answer 1

The Correct Option is C

Step 1: Understanding the Concept:
Gel electrophoresis separates charged molecules in an electric field. The direction of migration depends on the net charge of the molecule.
DNA is inherently negatively charged due to the phosphate groups in its backbone.
Step 2: Detailed Explanation:
Let's evaluate each statement:


(A) True. Gel electrophoresis is a versatile technique used for both nucleic acids (DNA and RNA) and proteins (typically using SDS-PAGE).

(B) True. Agarose gels are typically used for separating larger DNA fragments, while polyacrylamide gels (PAGE) offer higher resolution for smaller DNA fragments and proteins.

(C) False. Because DNA is negatively charged, it moves towards the positive electrode (anode) in an electric field, not the negative electrode (cathode). Opposites attract.

(D) True. Ethidium bromide is an intercalating agent that binds to DNA and fluoresces under UV light, allowing for the visualization of DNA bands.

Step 3: Final Answer:
The statement that is not true is (C).