DNA Replication and Checkpoint Control in S. DNA Replication and Checkpoint Control in S Phase. both strands are produced by DNA synthesis in the 5' to 3. S phase n. The phase of the mitotic cycle during which DNA synthesis occurs. DNA replication takes place during the synthesis phase of the cell cycle. The cell also forms a second centrosome during this phase. The G 1 checkpoint control mechanism ensures that everything is ready for DNA synthesis. Synthesis: S. determine the commitment into cell cycle and S phase entry. G 2 phase a relatively quiescent part of the cell cycle during interphase, lasting from the end of DNA synthesis (the S phase) until the start of cell division. 1. Mol Cell Biol. 2002 Nov;22(21):7459-72. Coupling of DNA synthesis and histone synthesis in S phase independent of cyclin/cdk2 activity. Nelson DM(1), Ye X, Hall C. S-phase (synthesis phase) is the part of the cell cycle in which DNA is replicated, occurring between G 1 phase and G 2 phase. Precise and accurate DNA replication is. DNA and histone synthesis are both triggered at the beginning of S phase by cyclin/cdk2 activity. Previous studies showed that inhibition of DNA synthesis with. A eukaryotic cell cannot divide into two, the two into four, etc. unless two processes alternate: doubling of its genome (DNA) in S phase (synthesis phase) of the. Definition. noun. A stage of interphase wherein the eukaryotic somatic cell makes a copy of its DNA (via DNA replication) (hence the name) Supplement.