During which phase of the cell cycle does the synthesis of enzymes necessary for genome replication occur?

The G1 phase, or Gap 1 phase, is a crucial part of the cell cycle that occurs before DNA synthesis begins. During this phase, the cell is primarily focused on growth and synthesizing the necessary components required for DNA replication. Enzymes and proteins that are vital for genome replication, including various forms of DNA polymerases and other proteins necessary for unwinding DNA and initiating replication, are produced during G1. This preparation ensures that the cell is ready for the subsequent S phase, where actual DNA synthesis occurs.

In contrast, during the S phase, the main activity is the replication of the DNA itself. G2 phase involves further preparation for mitosis and the synthesis of additional proteins, while the M phase encompasses mitosis where the cell divides. The activities occurring in G1 are foundational and set the stage for successful DNA replication in later phases.