During which phase of the cell cycle does DNA synthesis and replication occur?

DNA synthesis and replication occur during the S phase of the cell cycle. This phase is specifically designated for the duplication of the genetic material, which is essential for cell division. During the S phase, each chromosome is replicated to produce two identical sister chromatids, ensuring that when the cell divides, each daughter cell receives an exact copy of the DNA.

This process is critical for maintaining genetic consistency across cell generations. The S phase follows G1, where the cell grows and prepares for DNA synthesis, and precedes G2, which is focused on further growth and preparation for mitosis. M phase (mitotic phase) is where the actual division of the cell occurs, and it relies on the successful completion of the S phase. Therefore, the S phase is uniquely responsible for the comprehensive processes of DNA synthesis and replication.