Interphase is the active portion of thecell cycle that includes theG1,S, andG2 phases, where the cellgrows,replicates its DNA, and prepares formitosis, respectively. Interphase was formerly called the "resting phase," but the cell in interphase is not simplydormant. Calling it so would be misleading since a cell in interphase is very busysynthesizing proteins,transcribing DNA into RNA,engulfing extracellular material, andprocessing signals, to name just a few activities. The cell is quiescent only inG0. Interphase is the phase of thecell cycle in which a typicalcell spends 90% of its life. Interphase is the "daily living" ormetabolic phase of the cell, in which the cell obtainsnutrients andmetabolizes them, grows, replicates its DNA in preparation formitosis, and conducts other "normal" cell functions.[1]
A common misconception is that interphase is the first stage ofmitosis, but since mitosis is the division of thenucleus,prophase is actually the first stage.[2]
In interphase, the cell gets itself ready formitosis ormeiosis.Somatic cells, or normaldiploid cells of the body, go through mitosis in order to reproduce themselves through cell division, whereas diploidgerm cells (i.e., primaryspermatocytes and primaryoocytes) go throughmeiosis in order to create haploidgametes (i.e.,sperm andova) for the purpose of sexual reproduction.
There are three stages of cellular interphase, with each phase ending when acellular checkpoint checks the accuracy of the stage's completion before proceeding to the next. The stages of interphase are:
The duration of time spent in interphase and in each stage of interphase is variable and depends on both the type of cell and the species of organism it belongs to. Most cells of adultmammals spend about 24 hours in interphase; this accounts for about 90%-96% of the total time involved in cell division.[4]Interphase includes G1, S, and G2 phases.Mitosis andcytokinesis, however, are separate from interphase.
DNA double-strand breaks can berepaired during interphase by two principal processes.[5] The first process,non-homologous end joining (NHEJ), can join the two broken ends of DNA in theG1,S andG2 phases of interphase. The second process,homologous recombinational repair (HRR), is more accurate than NHEJ in repairing double-strand breaks. However HRR is only active during the S and G2 phases of interphase whenDNA replication is either partially or fully accomplished, since HRR requires two adjacenthomologous chromosomes.
When G2 is completed, the cell enters a relatively brief period of nuclear and cellular division, composed of mitosis and cytokinesis, respectively. After the successful completion of mitosis and cytokinesis, both resultingdaughter cells re-enter G1 of interphase.
In thecell cycle, interphase is preceded bytelophase andcytokinesis of theM phase. In alternative fashion, interphase is sometimes interrupted byG0 phase, which, in some circumstances, may then end and be followed by the remaining stages of interphase. After the successful completion of theG2 checkpoint, the final checkpoint in interphase, the cell proceeds toprophase, or in plants topreprophase, which is the first stage of mitosis.
G0 phase is viewed as either an extended G1 phase where the cell is neither dividing nor preparing to divide, or as a distinctquiescent stage which occurs outside of the cell cycle.[6]
Ingamete production, interphase is succeeded bymeiosis. Inprogrammed cell death, interphase is followed or preempted byapoptosis.
The transition region between two materials. For example between thefibre and matrix of acomposite material.
