Asynchronous cultures of E. coli were grown in 14N and then shifted to 15N medium containing a chemical C (0 minute) and incubated for two generation times (i.e. 40 minutes). Proportion of hybrid DNA (14N-15N) was measured at various time-points and results are depicted in the following table.
| Time | 0 minute | 10 minutes | 20 minutes | 30 minutes | 40 minutes |
| Hybrid DNA | 0% | 40% | 40% | 40% | 40% |
From the data, it was concluded that the chemical C inhibits DNA replication.
Which one of the following possibilities could be the likely mode of action of chemical C?
1
It inhibits the initiation of replication.
2
It inhibits the elongation phase of replication.
3
It inhibits the termination of replication.
4
It competes with dNTPs for incorporation into the newly synthesized DNA.