<P> The cell - division cycle is a vital process by which a single - celled fertilized egg develops into a mature organism, as well as the process by which hair, skin, blood cells, and some internal organs are renewed . After cell division, each of the daughter cells begin the interphase of a new cycle . Although the various stages of interphase are not usually morphologically distinguishable, each phase of the cell cycle has a distinct set of specialized biochemical processes that prepare the cell for initiation of cell divisions . </P> <P> The cell cycle consists of four distinct phases: G phase, S phase (synthesis), G phase (collectively known as interphase) and M phase (mitosis or meiosis). M phase is itself composed of two tightly coupled processes: karyokinesis, in which the cell's chromosomes are divided, and cytokinesis, in which the cell's cytoplasm divides forming two daughter cells . Activation of each phase is dependent on the proper progression and completion of the previous one . Cells that have temporarily or reversibly stopped dividing are said to have entered a state of quiescence called G phase . </P> <Table> <Tr> <Th> State </Th> <Th> Phase </Th> <Th> Abbreviation </Th> <Th> Description </Th> </Tr> <Tr> <Td> Resting </Td> <Td> Gap 0 </Td> <Td> </Td> <Td> A phase where the cell has left the cycle and has stopped dividing . </Td> </Tr> <Tr> <Td> Interphase </Td> <Td> Gap 1 </Td> <Td> </Td> <Td> Cells increase in size in Gap 1 . The G checkpoint control mechanism ensures that everything is ready for DNA synthesis . </Td> </Tr> <Tr> <Td> Synthesis </Td> <Td> </Td> <Td> DNA replication occurs during this phase . </Td> </Tr> <Tr> <Td> Gap 2 </Td> <Td> </Td> <Td> During the gap between DNA synthesis and mitosis, the cell will continue to grow . The G checkpoint control mechanism ensures that everything is ready to enter the M (mitosis) phase and divide . </Td> </Tr> <Tr> <Td> Cell division </Td> <Td> Mitosis </Td> <Td> </Td> <Td> Cell growth stops at this stage and cellular energy is focused on the orderly division into two daughter cells . A checkpoint in the middle of mitosis (Metaphase Checkpoint) ensures that the cell is ready to complete cell division . </Td> </Tr> </Table> <Tr> <Th> State </Th> <Th> Phase </Th> <Th> Abbreviation </Th> <Th> Description </Th> </Tr>

Dna replication occurs in which phase of the cell cycle