Histone methyltransferases are a class of enzymes that methylate certain amino acid sequences in histone proteins. A research team found that transcription of gene R decreases when histone methyltransferase activity is inhibited. Which scientific claim is most consistent with these findings?

A) DNA methylation inhibits transcription of gene R.
B ) Histone modifications of genes are usually not reversible.
C ) Histone methylation condenses the chromatin at gene R so transcription factors cannot bind to DNA.
D) Histone methylation opens up chromatin at gene R so transcription factors can bind to DNA more easily.

D) Histone methylation opens up chromatin at gene R so transcription factors can bind to DNA more easily.

Explanation:

The process of transferring the methyl group to amino acids of histone is known as histone methylation. From the question it can be concluded that the transcription of gene R should increase by the activation of gene R because it's inhibition was decreasing the transcription of gene R.

If the genes can't be accessed by RNA they could not be transcribed. So if the DNA is in condensed form RNA cannot access the R gene and would not be unable to transcribe it. In the given example the histone methylation would trigger the opening of gene R and then RNA will bind to it for its transcription.

So we can say choice D is the correct choice.

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