The cell cycle consists of several stages: Interphase (G1, S, G2), and Mitotic phase (M phase, which includes mitosis and cytokinesis). During these stages, the cell grows, replicates its DNA, and divides.
The resting but metabolically active stage of the cell cycle is Interphase, particularly the G0 phase. In the G0 phase, cells are in a resting state, but they are still metabolically active. They perform essential functions, such as protein synthesis, maintaining cell structure, and other maintenance tasks, but they do not prepare for cell division.
The G0 phase is typically observed in differentiated cells that have permanently exited the cell cycle, such as neurons and muscle cells. These cells are not actively dividing, but they still carry out the necessary functions required for survival.