What is Interphase?
Cells undergo continuous cell division, through which daughters cells are produced, which mature and also form their daughter cells, and this cycle continues. Cell cycle events include cell growth and cell division, the difference of which defines the stage of cell development where multiple metabolic reactions occur. Interphase is the preparation stage for mitosis and is also the longest phase of the cell cycle. Interphase occurs in the cytoplasm and cell nucleus.
Interphase stages in order
- Gap 1 (G1)
- Synthesis (S), and
- Gap 2 (G2).
The G1 and G2 stages represent the time of growth and preparation for mitosis.
The synthesis (S) phase is the cell copy or cell duplication phase of the DNA of its entire genome.
G1 Phase |Gap 1 (G1)
- This is the stage in which the cell undergoes normal growth and synthesizes high amounts of cell function proteins.
- Cell size and volume increase as more cell organelles are produced.
- The cell can only move to the next stage after S has synthesized enough ribosomes.
- As the phase is almost complete, the cell’s mitochondria fuse into a network of mitochondria for effective energy production for cell processes.
- If the cell cannot divide again, it enters G0.
S phase (Synthesis)
- This is the stage when the cell synthesizes and doubles its DNA.
- During doubling, the number of chromosomes remains constant, a process is known as semiconductor replication.
- Additionally, the new pack protein, known as histone, wraps around DNA copies to make it stable.
- During the S phase, more phospholipids are produced that form cell membranes and membranes of the cell organ.
G2 Phase |Gap 2 (G2)
- During this phase, the cell continues its growth phase as it prepares for cell division.
- Mitochondria will divide and continue to grow until mitosis begins.
- Besides, the plant chloroplast also divides into this stage.
Controlling the interphase
- At the end of Gap1 (G1), the cell is controlled by a checkpoint known as G1 / S, allowing the cell to investigate whether to undergo replication. It is at this checkpoint that DNA division or errors are checked to ensure that cell division is accomplished.
- During the investigation, various proteins exchange a mechanism with DNA called molecular switching.
- The molecular switch is an on and off process and continues through the S phase that allows damaged cells to undergo apoptosis (programmed death).
- Again in the G2 phase, a second probe occurs after the synthesis of DNA in the S phase.
- The second checkpoint uses kinase enzymes that regulate various steps in the cell division cycle.
- A typical example of a kinase enzyme in cell division is the cyclin-dependent kinase (CDK) that uses cell signals to switch cell mechanisms, especially when a genetic mutation is detected.
- Cyclin-Dependent Kinase is activated by a regulatory protein complex (tumor suppressors) that regulates cell growth and induces apoptotic mechanisms of the wrong cells.
- In the case of a genetic mutation in regulatory proteins at the checkpoint, a permanent molecular switch to an uncontrolled cell multiplication is triggered that may lead to carcinogenesis or tumor development.
- Additionally, if the cell misses at the second checkpoint, cancer cells may develop for example neoplasia due to uncontrolled cell division.
Interphase and the cell cycle
- Interphase prepares the cell for later stages of cell division such as mitosis and cytokinesis.
- Since interphase is a preparation step for cell division processes, it enables the cell to grow, so that they can synthesize organelles that allow the cell to function adequately.
- Interphase stages prepare cells for mitosis by meeting external and internal conditions for the cell system.
- After the G2 phase, the cell proceeds to prophase or pre-prophase in plants.
- Prophase is the initial stage of mitotic cell division.
- Note, some cells undergo G0, a phase in the G1 phase of cell division, which does not allow cell division.
- Some cells that do not undergo cell division remain permanently in G0
Interphase in different cells
- Different cells may have different interface processing mechanisms.
- A typical eukaryotic cell undergoes the later stages of interfaces i.e. G1, S, and G2. Cells that undergo cell division spend approximately 95% of their time in interfaces.
- Cells that do not undergo cell division (which have no DNA replication) are permanently at the interphase stage such as neuron cells while cells that are actively dividing such as skin cells that are continuously dividing Interfaces must enter where all necessary organelles accumulate while actively replicating during interphase.
- Cancer cells develop due to errors occurring during the second checkpoint, G2.
- A mutation that affects the functioning of regulatory proteins responsible for activating cyclin-dependent kinase enzymes leads to permanent molecular switching, leading to uncontrolled cell division carcinogenesis or tumor growth.
- The interphase phase of cell division does not occur in bacterial cells because the mechanism of cell division is meiosis whereby the interphase is known as a specialized phase known as interkinesis, and DNA replication does not occur.
What is Interphase? Stages, cell cycle, and Interphase