Interphase-Definition, Stages, Cell Cycle, Diagram

Interphase Definition

Interphase occurs inside the cytoplasm and nucleus of the cell. Cells constantly divide, resulting in daughter cells that develop, mature, and then divide again to generate more daughter cells, and so the cycle goes. The cell cycle involves both cell growth and division, and the interphase is the phase of cell development during which a variety of metabolic activities happen. Interphase, the longest phase of the cell cycle, is the preparation step for mitosis.

Interphase stages: What happens during the interphase?

Gap 1 (G1)

Synthesis (S), and

Gap 2 (G2).

The G1 and G2 phases signify the periods of growth and mitotic preparation.

The synthesis (S) phase is when a cell copies or duplicates the DNA that makes up its whole genome.

Gap 1 (G1)

  • At this phase, the cell undergoes normal development and cell activity while producing an abundance of proteins.
  • As numerous organelles are produced, the volume and size of the cell increase.
  • Following sufficient ribosome production, the cell could only continue to the S phase.
  • When the phase comes to a conclusion, the mitochondria of the cell start to network together, enabling efficient energy generation for cell operations.
  • If a cell can not split once more, it moves into the G0 stage.

Synthesis, S phase

  • During this time, the cell synthesises DNA and doubles its quantity.
  • Semi-conservative replication, which doubles the number of chromosomes while maintaining the same number, is a process.
  • In order to stabilise the DNA copies, brand-new packed proteins called histones wrap around them.
  • The phospholipids that make up the cell membrane and the membranes of the cell organelles are generated in greater quantities during the S phase.

Gap 2 (G2)

  • The cell continues to expand during this phase as it gets ready to divide.
  • The process of mitosis will not begin until the mitochondria have multiplied and grown.
  • In this phase, the plant’s chloroplast also splits.

Controlling the interphase

  • The G1/S checkpoint, which occurs at the end of Gap 1 (G1), regulates the cell and determines whether or not it will replicate.
  • To ensure that cell division proceeds smoothly, DNA damage or mistakes are examined at this checkpoint.
  • Molecular switching happens while various proteins bind with DNA during the testing procedure.
  • In the S phase, the molecular switch swings between on and off states, allowing damaged cells to undergo apoptosis (programmed cell death).
  • In the G2 phase, a second checkpoint happens after DNA synthesis in the S phase.
  • During the second checkpoint, kinase enzymes that govern several phases of cell division cycles are utilised.
  • In cell division, the Cyclin-Dependent Kinase (CDK) is a good demonstration of a kinase enzyme. Cellular activities are modified by cell signals, particularly while a genetic mutation is identified.
  • Regulating protein complexes (tumour suppressors), which regulate cell development and cause erroneous cells to undergo apoptosis, activate the Cyclin-Dependent Kinase.
  • In the case of a genetic mutation in the regulatory proteins at the checkpoint, a permanent molecular switch is activated, leading to unregulated cell proliferation, which may lead to carcinogenesis or tumour formation.
  • Furthermore, cancer cells may arise if the second checkpoint is bypassed. For instance, unregulated cell division can result in neoplasia.

Interphase and the cell cycle

  • The interphase gets the cell ready for mitosis and cytokinesis, the following phases of cell division.
  • Interphase enables the cell to grow and manufacture the organelles required for the cell to function normally after it has achieved maturity. Interphase is a preliminary phase for the cell division mechanisms.
  • By ensuring that both the internal and external prerequisites for cell mechanisms are met, the phases of the interphase prepare the cell for mitosis.
  • The cell enters prophase, or pre-prophase in plants, after the G2 stage.
  • The first stage of mitotic cell division is known as prophase.
  • Be aware that some cells enter the G1 stage of cell division through the G0 stage, which prevents cell division.
  • Some cells that don’t divide stay in the G0 stage forever.

Interphase in different cells

  • The processes used for interphase processing may differ between cells.
  • A normal eukaryotic cell progresses through the G1, S, and G2 stages of the interphase. During cell division, cells spend around 95% of their time in the interphase.
  • When cells which are constantly multiplying, like skin cells, should reach the interphase where they acquire all the essential organelles while replicating vigorously, cells which do not perform cell division (have no DNA replication) are often in the interphase.
  • Errors that occur at the second checkpoint, G2, result in the formation of cancer cells.
  • Permanent molecular switching is caused by a mutation that disrupts the activity of regulatory proteins responsible for activating cytokine-dependent kinase enzymes. This unregulated cell division encourages carcinogenesis, or tumour formation.
  • Bacterial cells don’t really undergo the interphase stage of cell division because they are split by the meiotic process, wherein the interphase is really a different phase known as interkinesis, and DNA replication does not occur.

References and Sources

  • Microbiology by Prescott, 5th Edition
  • https://www.expii.com/t/what-is-interphase-overview-diagrams-10154
  • https://bio.libretexts.org/Bookshelves/Introductory_and_General_Biology/Book%3A_General_Biology_(Boundless)/10%3A_Cell_Reproduction/10.2%3A_The_Cell_Cycle/10.2B%3A_The_Mitotic_Phase_and_the_G0_Phase
  • Biology Dictionary/interphase
  • Teach me Physiology/ The Cell Cycle
  • https://sciencing.com/list-3-steps-occur-during-interphase-17577.html
  • https://ib.bioninja.com.au/standard-level/topic-1-cell-biology/16-cell-division/interphase.html
  • https://en.wikipedia.org/wiki/Interphase#:~:text=Interphase%20is%20the%20portion%20of,prepares%20for%20mitosis%20(G2).
  • https://www.gwisd.us/vimages/shared/vnews/stories/4ebbe99bda63a/Mitosis%20and%20Cell%20Division%20Text.pdf
  • https://www.cyclacel.com/research_science_cell-cycle.shtml
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