During which phase of the cell cycle does the cell duplicate its contents except for chromosomes?

The G1 phase, or the first gap phase of the cell cycle, is characterized by the growth and preparation of the cell for DNA replication. During this phase, the cell increases in size and synthesizes various proteins and organelles that are necessary for the next phase, which is the synthesis phase (S phase) where the actual duplication of the chromosomes occurs. It is during G1 that the cell ensures it has enough resources and energy to duplicate its contents effectively. This phase sets the stage for successful DNA synthesis by providing the necessary foundation.

In contrast, the S phase is specifically when DNA is replicated, marking the duplication of chromosomes. The G2 phase follows S and involves further preparation for mitosis, including the duplication of certain organelles and additional synthesis, but it is not primarily focused on contents other than the chromosomes. The G0 phase represents a quiescent state where cells are metabolically active but not actively dividing, and thus does not involve content duplication as G1 does.