Interphase is divided into what three stages? What happens in each?
How much of the cell cycle is spent in interphase?
Interphase is divided into three stages: G1 (gap 1), S (synthesis), and G2 (gap 2).
1. G1 phase: During this stage, the cell grows in size, synthesizes proteins, and performs its normal functions. It prepares for DNA replication by ensuring that all necessary materials for DNA synthesis are available. G1 phase is also a critical checkpoint, where the cell checks for any damage to DNA and evaluates if it is ready to proceed to the next stage.
2. S phase: In this stage, DNA replication occurs. The cell duplicates its entire genome, including chromosomes, in order to prepare for cell division. Each chromosome is replicated to produce two identical copies called sister chromatids, which are held together at the centromere.
3. G2 phase: After DNA replication in the S phase, the cell enters G2 phase. During this stage, the cell prepares for mitosis or meiosis by synthesizing additional proteins and organelles required for cell division. The cell continues to grow in size, and a second checkpoint occurs to ensure that DNA replication was accurately completed and there are no damages in the DNA.
Approximately 90% of the cell cycle is spent in interphase, making it the longest phase.