Synthesis of DNA occurs in which phase of cell cycle

 # Synthesis of DNA occurs in which phase of cell cycle?

 A. Mitosis-M phase

B. Gap- G1 phase

C. Gap-G2 phase

D. Synthesis- S phase

The correct answer is D. Synthesis - S phase.

S phase (Synthesis Phase) is the phase of the cell cycle in which DNA is replicated, occurring between G1 phase and G2 phase. Since accurate duplication of the genome is critical to successful cell division, the processes that occur during S-phase are tightly regulated and widely conserved. 

Entry into S-phase is controlled by the G1 restriction point (R), which commits cells to the remainder of the cell-cycle if there is adequate nutrients and growth signaling. This transition is essentially irreversible; after passing the restriction point, the cell will progress through S-phase even if environmental conditions become unfavorable.