GENETICS AND EVOLUTION
MOLECULAR BASIS OF INHERITANCE
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Question
[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
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DNA replication is occurring.
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The DNA is condensed into a Chromatin Fibre.
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The DNA double helix is exposed.
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Transcription is occurring.
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Detailed explanation-1: -Final answer: The association of histone H1 with a nucleosome indicates the DNA is condensed into a Chromatin Fibre.
Detailed explanation-2: -Chromosomal DNA is packaged inside microscopic nuclei with the help of histones. These are positively-charged proteins that strongly adhere to negatively-charged DNA and form complexes called nucleosomes. Each nuclesome is composed of DNA wound 1.65 times around eight histone proteins.
Detailed explanation-3: -Histone H1, also known as ‘linker histone’, plays a dominant role in establishing the compaction state of an array of nucleosomes as well as influencing the conformation. H1 has three domains: a central globular domain that binds near the entry/exit site of linker DNA on the nucleosome, and extended N-and C-terminus.
Detailed explanation-4: -H1 stabilizes nucleosomes by binding to the dyad region between the entry and exit sites of DNA. The H1 GD is sufficient for binding to the nucleosome. Binding of the GD protects an additional 10bp from endonuclease digestion at both sides of nucleosome [4].