Question

Arrange the following DNA fragments A, B, C, D separated after Gel Electrophoresis in increasing order of number of their base pairs

• A. A, B, C, D
• B. A, D, C, B
• C. B, C, D, A
• D. C, B, D, A

Hint:

In gel electrophoresis, remember the simple rule: "Small runs fast." The fragments at the bottom of the gel are the smallest, and those at the top are the largest. Always check if the question asks for increasing or decreasing order of size.

Answer 1

The Correct Option is B

Step 1: Understanding the Concept:
Agarose gel electrophoresis separates DNA molecules based on size.
DNA, being negatively charged, migrates through the agarose gel from the negative to the positive electrode when an electric field is applied.
The gel acts as a sieve, with smaller DNA fragments migrating faster and farther than larger ones.
Step 2: Detailed Explanation:


DNA samples are loaded into "Wells" at the top of the gel.

The migration distance is inversely proportional to DNA fragment size.

Based on the fragment positions:


Fragment A traveled the farthest, indicating it is the smallest.

Fragment D traveled the second farthest.

Fragment C traveled less far than D.

Fragment B traveled the shortest distance, indicating it is the largest.


The question requires ordering the fragments by increasing number of base pairs (smallest to largest).

Step 3: Final Answer:
The order from smallest to largest DNA fragment size is A, D, C, B.