Question

If chromatin is in a closed confirmation, nucleosome position and histone composition

a) Remain unchanged
b) Are more variable
c) Become more rigid
d) Are disrupted

Answer 1

When chromatin is in a closed state, the nucleosome position and histone composition remain unchanged, preserving the silenced state of the gene where transcription is not meant to occur.

Step-by-step explanation:

If chromatin is in a closed configuration, the nucleosome position and histone composition remain unchanged. In a closed chromatin state, epigenetic tags like methyl groups reinforce the tight binding between DNA and histone proteins, which prevents transcription factors and RNA polymerase from accessing the DNA. Closed chromatin configurations are characteristic of a silenced gene state, where transcription is not to occur. This state maintains the nucleosome position and keeps the histone composition in a fixed arrangement that is not easily altered. These modifications to the histones and DNA do not change the base sequence of the DNA but affect how tightly the DNA is associated with the histone proteins, keeping it in a 'closed' or inaccessible state for transcription.