Answer: two each of H2A, H2B, H3 and H4.
- A two molecules of histone H1 only
- B four different histones, one each
- C two each of H2A, H2B, H3 and H4
- D eight molecules of a single histone
Correct answer: C. two each of H2A, H2B, H3 and H4
Explanation: The nucleosome core is an octamer containing two molecules each of the histones H2A, H2B, H3 and H4; H1 lies outside, sealing the DNA.
Helicase unwinds the double helix at the replication fork; one new strand (leading) is synthesised continuously toward the fork, while the other (lagging) must be made in short, separate Okazaki fragments because DNA polymerase only adds nucleotides 5'→3'.
Concept context
DNA structure, replication, transcription, translation, the genetic code, and gene regulation (lac operon). The single most important chapter for NEET molecular biology.