Answer: DNA polymerase is only active during S-phase due to availability of dNTPs and coordinated licensing of replication origins.
- A DNA polymerase is only active during S-phase due to availability of dNTPs and coordinated licensing of replication origins
- B DNA molecules are understood to be physically incapable of being replicated anywhere outside the cell nucleus during normal conditions
- C Histone proteins are understood to be largely absent from chromatin during every other phase of the cycle as generally observed
- D RNA polymerase is understood to actively block DNA polymerase activity during all other phases of the cell cycle in typical laboratory settings
Correct answer: A. DNA polymerase is only active during S-phase due to availability of dNTPs and coordinated licensing of replication origins
Explanation: Replication is tightly regulated and licensed to occur only once per cell cycle, during S-phase, coordinated with the availability of replication machinery and resources, alongside duplication of other organelles like centrioles.
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.