Which phase comes after Gap 1 (G1) and before M phase (mitosis)?

Which phase comes after Gap 1 (G1) and before M phase (mitosis)?

• A. G1
• B. S phase (synthesis)
• C. G2
• D. Cytokinesis

Answer: (B)

After the cell grows in G1, DNA must be copied so each new cell will have a full genome. That copying happens during the S phase, the period dedicated to DNA synthesis. Only after DNA is duplicated does the cell move on to G2 for final preparations and then into M phase for mitosis and cytokinesis. Cytokinesis actually occurs after mitosis, during the division of the cytoplasm, so it isn’t the phase between G1 and M. So the phase that comes after G1 and before M is the S phase, the DNA replication stage.

After the cell grows in G1, DNA must be copied so each new cell will have a full genome. That copying happens during the S phase, the period dedicated to DNA synthesis. Only after DNA is duplicated does the cell move on to G2 for final preparations and then into M phase for mitosis and cytokinesis. Cytokinesis actually occurs after mitosis, during the division of the cytoplasm, so it isn’t the phase between G1 and M. So the phase that comes after G1 and before M is the S phase, the DNA replication stage.