Answer :

(a)

i)

• 3 types

• RNA Polymerase –II

ii) Splicing /Introns are removed and exons are joined in a definite order, undergoes capping /at 5' end where unusual nucleotide (methyl guanosine triphosphate) is added , tailing/ at 3' end where (200-300) adenylate residues are added.

or

(b) A set of positively charged proteins called histones, due to presence of lysine and arginine( basic amino acids), holds the negatively charged DNA around it in a coiled manner, histones are organized to form a unit of eight molecules (histone octamer), a typical nucleosome contains 200 bp of DNA helix, Nucleosomes constitute repeating units of a structure in nucleus called chromatin thread ( like bodies as “beads on string” structure in a nucleus).