Question

Which of the following is most critical for the association between histones and DNA?

Histones are small proteins.
Histones are highly conserved (i.e., histones are very similar in every eukaryote).
There are at least five different histone proteins in every eukaryote.
Histones are synthesized in the cytoplasm.
Histones are positively charged.

Answer 1

The most critical factor for the association between histones and DNA is that histones are positively charged.

Step-by-step explanation:

The most critical factor for the association between histones and DNA is that histones are positively charged. Histones are positively charged due to their basic amino acids, which is critical for their association with the negatively charged DNA, leading to the formation of nucleosomes.

This positive charge allows the histones to bind to the negatively charged phosphodiester backbone of the DNA. The DNA wraps around an octamer of histones to form structures called nucleosomes, which help in DNA packaging. The positively charged histones enable them to arrange themselves uniformly along the DNA double helix, establishing a stable association.

Answer 2

The correct answer is - Histones are positively charged.

Step-by-step explanation:

Histone is an octamer that is made up of four proteins and each protein has 2 copies. These proteins are H2A, H2B, H3, and H4. Histone proteins are mainly made up of positively charged amino acids like arginine and lysine which gives histone proteins an overall positive charge.

This positive charge of histone plays important role in the binding of DNA around it because phosphate group present in the DNA makes DNA negatively charged molecules that are attracted by positively charged histone protein by electrostatic interaction.

This interaction results in the wrapping of DNA around the histone proteins and then compaction of DNA into chromatin. Therefore the right answer is- histones are positively charged.