Final answer:
DNA replication occurs during the S phase of the cell cycle, which is designed to ensure that each daughter cell receives a precise copy of the DNA.
Step-by-step explanation:
DNA replication happens during the S phase of the cell cycle. This is the period also known as the synthesis phase which takes place before mitosis and cell division. Within the cell cycle, there are distinct phases such as G1 (growth and protein synthesis), S (DNA replication), and G2 (further growth and preparation for mitosis), which all come under the larger umbrella of interphase. The purpose of DNA replication in the S phase is to ensure that each daughter cell receives an identical copy of the DNA, which is crucial for maintaining the organism's genetic continuity. The base pairing rules play an essential role during this replication process, ensuring that each new strand is an exact match to the original.