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Question
Assertion: Nucleosome consists of a strand of DNA coiled around a core of histone proteins.
Reason: The histone proteins forming the core of nucleosome are of four major types, viz, H1, H2, H3 and H4.
Options
Both assertion and reason are true, and reason is the correct explanation of the assertion.
Both assertion and reason are true, but reason is not the correct explanation of the assertion.
Assertion is true but reason is false.
Both assertion and reason are false.
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Solution
Assertion is true but reason is false.
Explanation:
The assertion is correct because a nucleosome is the fundamental unit of chromatin, formed when a segment of negatively charged DNA wraps around a positively charged core of histone proteins. However, the reason is false because the histone core (octamer) is composed of two molecules each of four specific histone types: H2A, H2B, H3, and H4. The H1 histone mentioned in the reason is not a part of this central core; instead, it is known as a “linker histone” that binds to the outside of the nucleosome to stabilise the DNA as it enters and exits the structure.
