Which phase of the cell cycle is the period of cell growth and the preparation of chromosomes for DNA replication?

The G1 phase, or Gap 1 phase, is characterized by significant cellular growth and the preparation for DNA replication. During this phase, the cell increases in size, synthesizes various proteins, and produces organelles, all essential for the subsequent stages of the cell cycle. This is a crucial period where the cell assesses its environment to ensure conditions are suitable for division.

Additionally, the G1 phase involves the synthesis of RNA and proteins that are necessary for DNA replication, making it a preparatory stage for the S phase that follows, where actual DNA synthesis occurs. The activities in G1 set the foundation for successful progression through the rest of the cell cycle, including replication of the chromosomes and ultimately producing two daughter cells.

The other phases serve different functions: the S phase is primarily focused on DNA synthesis, the G2 phase encompasses preparation for mitosis following DNA replication, and the M phase is where mitosis occurs, leading to cell division. Thus, G1 is distinct in its role of growth and preparation ahead of the replication stage.