interfasen

Interfase, in Dutch terminology, is the period of the cell cycle between successive mitotic divisions in eukaryotic cells. During interfase the cell grows, duplicates its DNA, and prepares for division. In Dutch usage the term interfase is used, with the plural interfasen.

Interfase consists of three phases: G1, S, and G2. In G1, the cell increases in size, produces RNA and proteins, and enhances metabolic activity. The S phase is when DNA replication occurs, resulting in duplicated chromosomes and the possibility of centrosome duplication in animal cells. In G2, the cell continues to grow and synthesizes proteins required for mitosis, while also performing DNA repair and quality control to ensure readiness for division.

DNA content and chromatin state change throughout interfase. During S phase the genome is replicated, so DNA content doubles from 2C to 4C, yet chromosomes are not yet condensed into the mitotic form and the nucleus remains intact. Transcription is active and chromatin is relatively less condensed compared with mitosis, facilitating replication and growth.

Regulation and checkpoints play a central role in interfase. Progress through G1, S, and G2 is governed by cyclin-dependent kinases (CDKs) and various cyclins. The G1/S checkpoint assesses cell size, nutrient status, and DNA integrity before replication begins, while the G2/M checkpoint ensures that DNA replication is complete and undamaged before mitosis. External growth signals influence entry into and duration of interfase. Some cells can exit interfase into a quiescent G0 state.

Variation and context: Interfase length varies by cell type and condition. Many differentiated or post-mmitotic cells spend extended periods in G0, while others rapidly progress through interfase. In bacteria, which divide by binary fission, a distinct interfase is not present.