In which phase does DNA synthesis occur?

DNA synthesis occurs during the S phase of the cell cycle. During this phase, the cell's entire genetic material is duplicated in preparation for cell division. This process is crucial because it ensures that both daughter cells receive an identical set of chromosomes after mitosis or meiosis.

In the S phase, the enzymes involved in DNA replication, including DNA polymerases, are activated to unwind the DNA double helix and synthesize new strands based on the existing templates. This results in the formation of two sister chromatids for each chromosome.

The G1 phase precedes the S phase and is primarily focused on cell growth and the accumulation of materials needed for DNA synthesis. The G2 phase follows the S phase and involves further preparation for cell division, including the synthesis of proteins required for mitosis. The M phase, or mitotic phase, is when actual cell division occurs, but DNA synthesis has already been completed by that time. Therefore, the S phase is distinctly recognized as the phase where the critical process of DNA synthesis takes place.