Question

Assertion: Repetitive DNA appears as a different peak in density gradient centrifugation.
Reason: The repetitive sequence has a base composition distinct from the genome average.

• A. Both the assertion and reason are true and the reason is the correct explanation of the assertion
• B. Both assertion and reason are true but the reason is not the correct explanation of the assertion
• C. Assertion is true but the reason is false
• D. Both the assertion and the reason are false

Answer 1

The correct option is A Both the assertion and reason are true and the reason is the correct explanation of the assertion

In the density gradient centrifugation, genomic DNA forms two peaks. The bigger and broader one represents the bulk genomic DNA while the smaller one represents satellite DNA. The satellite DNA is further classified as micro- or mini-satellite on the basis of base composition, length of the segment, and the number of repetitive units. The repetitive sequence has a base composition distinct from the genome average, which allows it to form a separate fraction by virtue of its distinct buoyant density. So in the given statement both the assertion and reason are true and the reason is the correct explanation of the assertion.