Question

Assertion (A): DNA fragments are positively charged.
Reason (R): DNA fragments are separated by gel electrophoresis technique.

• A. A and R are correct. R is the correct explanation of A.
• B. A and R are correct. R is not the correct explanation of A.
• C. A is correct but R is incorrect.
• D. A is incorrect but R is correct.

Hint:

Remember, DNA is negatively charged due to the phosphate groups, and gel electrophoresis separates DNA fragments based on size and charge.

Answer 1

The Correct Option is D

Analysis of DNA Charge and Gel Electrophoresis

• Assertion (A) is incorrect: DNA fragments are negatively charged due to the presence of phosphate groups on the DNA backbone.
  When an electric field is applied during gel electrophoresis, negatively charged DNA fragments move toward the positive electrode.
• Reason (R) is correct: DNA fragments are separated by gel electrophoresis.
  The technique works by applying an electric field to a gel matrix, allowing DNA fragments to migrate based on their size and charge.
  Since DNA is negatively charged, it moves towards the positive electrode.

Thus, the correct explanation is that R is correct, but A is incorrect.

Therefore, the correct answer is (D).