question_answer

Directions : (6 - 10)

Read the passage given below and answer the following questions.

In eukaryotes, DNA organisation is much more complex. There is a set of positively charged, basic proteins called histones. A protein acquires charge depending upon the abundance of amino acids residues with charged side chains. Histones are rich in the basic amino acid residues lysines and arginines. Both the amino acid residues carry positive charges in their side chains. Histones are organised to form a unit of eight molecules called as histone octamer.  Histones : \[{{H}_{1}},\,\,{{H}_{2}}A,\,\,{{H}_{2}}B,\,\,{{H}_{3}}\]and \[{{H}_{4}}\]. These are always basic proteins. The negatively charged DNA is wrapped around the positively charged histone octamer to form a structure called nucleosome or nu body. DNA connecting two adjacent nucleosome is called interbead or linker DNA. It bearr \[{{H}_{1}}\]histone protein or plugging or marker protein. A typical nucleosome contains 200 bp of DNA helix. Nucleosomes constitute the repeating unit of a structure in nucleus called chromatin, thread-like stained i.e., coloured bodies seen in nucleus. The nucleosomes in chromatin are seen as 'beads-on-string' structure when viewed under electron microscope (EM). The beads-on-string structure in chromatin is packaged to form chromatin fibers that are further coiled and condensed at metaphase stage of cell division to form chromosomes. The packing of chromatin, at higher level requires additional set of proteins that collectively are referred to as Non-histone Chromosomal (NHC) proteins (negatively charged).

Histone protein of DNA is

A) Positively charged

B) Basic in nature

C) Acidic in nature

D) Both [a] and [b]