OBJECTIVE LIFE SCIENCE
MOLECULAR BIOLOGY
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Question
[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
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the addition of lysine to histone tails, allowing transcription to occur.
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the increased translation rate of a gene.
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the addition of an acetyl group to the tail of a histone protein which packs the DNA tighter, not allowing the expression of the genes.
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the addition of an acetyl group to the tail of a histone protein which unpacks the DNA, allowing the genes to be expressed.
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Detailed explanation-1: -Histone acetyltransferases HATs add an acetyl group to the -amino group of lysine using acetyl CoA as a cofactor, which neutralizes the positive charge on lysine, weakens the histone-DNA interaction, and makes genes accessible [25]. HATs are a diverse set of proteins.
Detailed explanation-2: -The addition of the acetyl group neutralizes this positive charge and hence reduces the binding between histones and DNA, leading to a more open structure which is more accessible to the transcriptional machinery. Histone acetylation therefore leads to transcriptional activation.
Detailed explanation-3: -A widely accepted hypothesis is that histone acetylation, by reducing the positive charge of histone tails, releases them from their interaction with DNA. This is thought to result in the observed enhanced transcription factor binding to nucleosomes containing acetylated histones (43, 70, 72).