Question

At what stage of the cell cycle are histone proteins synthesised in a eukaryotic cell?

(a) During G₂-stage of prophase

(b) During S-phase

(c) During entire prophase

(d) During telophase

Answer 1

Correct option  (b) During S-phase

Explanation :

During S-phase of cell cycle synthesis of histone proteins takes place because at this stage the amount of DNA per cell get double to that of somatic number. Histone proteins are basic proteins and are used in packing of eukaryotic (absent in prokaryotes) DNA. DNA and histones together comprise chromatin, forming bulk of the eukaryotic chromosomes. Histones are of five major kinds H1, H2A,  H2B, H3 and H4. H1 histones link neighbouring nucleosomes.