Editing Interphase

{{short description|G1, S and G2 phases of the cell cycle}}
{{distinguish|Interface (chemistry)}}
{{About|the phase in the cell cycle|the video game|Interphase (video game)}}
[[File:Interphase.png|thumb|right|159px|An illustration of interphase. The [[chromatin]] has not yet condensed, and the cell is undergoing its normal functions.]]
[[File:Interphase and part of Telophase of HT1080.PNG|thumb |right|159px|An image of the nucleus of a cell ([[HT1080]]) currently in interphase (likely G1).  Note:  [[Cytoplasm]] of this cell or the neighboring cell is not visible (top-left), which is currently in the [[telophase]] of [[mitosis]]. Image taken using an optical microscope and [[DAPI]] staining of DNA.]]
'''Interphase''' is the active portion of the [[cell cycle]] that includes the [[G1 phase|G1]], [[S phase|S]], and [[G2 phase|G2]] phases, where the cell [[Cell growth|grows]], [[DNA replication|replicates its DNA]], and prepares for [[mitosis]], respectively. Interphase was formerly called the "'''resting phase'''," but the cell in interphase is not simply [[G0 phase|dormant]]. Calling it so would be misleading since a cell in interphase is very busy [[Protein biosynthesis|synthesizing proteins]], [[Transcription (biology)|transcribing DNA into RNA]], [[Endocytosis|engulfing extracellular material]], and [[Signal transduction|processing signals]], to name just a few activities. The cell is quiescent only in [[G0 phase|G0]]. Interphase is the phase of the [[cell cycle]] in which a typical [[cell (biology)|cell]] spends most of its life. Interphase is the "daily living" or [[Metabolism|metabolic]] phase of the cell, in which the cell obtains [[Nutrient|nutrients]] and [[metabolism|metabolizes]] them, grows, replicates its DNA in preparation for [[mitosis]], and conducts other "normal" cell functions.<ref name=Marieb2000>{{cite book |last=Marieb | first=Elaine | name-list-style = vanc | title=Essentials of human anatomy and physiology |publisher=Benjamin Cummings |location=San Francisco |year=2000 |isbn=978-0805349405 }}</ref>

A common misconception is that interphase is the first stage of [[mitosis]], but since mitosis is the division of the [[Cell nucleus|nucleus]], [[prophase]] is actually the first stage.<ref>{{cite web | url = http://www.biology.arizona.edu/Cell_bio/tutorials/cell_cycle/cells3.html | title = The Cell Cycle & Mitosis Tutorial | work = The Biology Project&nbsp;– Cell Biology. | publisher = University of Arizona }}</ref>

In interphase, the cell gets itself ready for [[mitosis]] or [[meiosis]]. [[Somatic cell]]s, or normal [[diploid]] cells of the body, go through mitosis in order to reproduce themselves through cell division, whereas diploid [[germ cell]]s (i.e., primary [[spermatocyte]]s and primary [[oocyte]]s) go through [[meiosis]] in order to create haploid [[gametes]] (i.e., [[sperm]] and [[ovum|ova]]) for the purpose of sexual reproduction.

==Stages of interphase==
There are three stages of cellular interphase, with each phase ending when a [[Cell cycle checkpoint|cellular checkpoint]] checks the accuracy of the stage's completion before proceeding to the next. The stages of interphase are:

* [[G1 phase|G<sub>1</sub>]] (Gap 1), in which the cell grows and functions normally. During this time, a high amount of [[protein biosynthesis|protein synthesis]] occurs and the cell grows (to about double its original size) – more [[organelle]]s are produced and the volume of the [[cytoplasm]] increases. If the cell is not to divide again, it will enter [[G0 phase|G<sub>0</sub>]].<ref>{{cite book | vauthors = Cummings MR | date = 2014 | title = Human Heredity: Principles and Issues | edition = 10th | pages =  28–29 | location = Belmont, CA | publisher = Brooks/Cole }}</ref>
* [[S phase|Synthesis]] (S), in which the cell synthesizes its DNA and the amount of DNA is doubled but the number of chromosomes remains constant (via [[semiconservative replication]]).
* [[G2 phase|G<sub>2</sub>]] (Gap 2), in which the cell resumes its growth in preparation for division. The cell continues to grow until mitosis begins. In plants, chloroplasts divide during G2.
* In addition, some cells that do not divide often or ever, enter a stage called [[G0 phase|G<sub>0</sub>]] (Gap zero), which is either a stage separate from interphase or an extended [[G1 phase|G<sub>1</sub>]].
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 adult [[mammal]]s spend about 24 hours in interphase; this accounts for about 90%-96% of the total time involved in cell division.<ref>{{cite book | vauthors = Mader SS | date = 2007 | title = Biology | edition = 9th | publisher = McGraw Hill Higher Education | location = Boston, MA, USA | isbn = 978-0-07-325839-3 }}</ref>
Interphase includes G1, S, and G2 phases. [[Mitosis]] and [[cytokinesis]], however, are separate from interphase.

DNA double-strand breaks can be [[DNA repair|repaired]] during interphase by two principal processes.<ref>Shibata A.  Regulation of repair pathway choice at two-ended DNA double-strand breaks.  Mutat Res. 2017 Oct;803-805:51-55. doi: 10.1016/j.mrfmmm.2017.07.011. Epub 2017 Jul 29. Review. PMID 28781144</ref>  The first process, [[non-homologous end joining]] (NHEJ), can join the two broken ends of DNA in the [[G1 phase|G1]], [[S phase|S]] and [[G2 phase|G2]] phases of interphase. The second process, [[homologous recombination]]al 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 when [[DNA replication]] is either partially or fully accomplished, since HRR requires two adjacent [[homologous chromosomes]].

==Interphase within sequences of cellular processes==

===Interphase and the cell cycle===
When G<sub>2</sub> 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 resulting [[daughter cell]]s re-enter G<sub>1</sub> of interphase.

In the [[cell cycle]], interphase is preceded by [[telophase]] and [[cytokinesis]] of the [[Cell division|M phase]]. In alternative fashion, interphase is sometimes interrupted by [[G0 phase|G<sub>0</sub> phase]], which, in some circumstances, may then end and be followed by the remaining stages of interphase. After the successful completion of the [[Cell cycle checkpoint#G2 Checkpoint|G<sub>2</sub> checkpoint]], the final checkpoint in interphase, the cell proceeds to [[prophase]], or in plants to [[preprophase]], which is the first stage of mitosis.

G<sub>0</sub> phase is viewed as either an extended G<sub>1</sub> phase where the cell is neither dividing nor preparing to divide, or as a distinct [[wikt:quiescent|quiescent]] stage which occurs outside of the cell cycle.<ref>{{cite web | url = http://www.madsci.org/posts/archives/nov99/942335648.Cb.r.html | title = Re: Are the cells in the G0 (g zero) phase of mitosis really suspended? | first = Erin | last = Cram | name-list-style = vanc | publisher = Molecular and Cellular Biology, University of California, Berkeley. 1999. | work = MadScience Network }}</ref>

===Interphase and other cellular processes===
In [[gamete]] production, interphase is succeeded by [[meiosis]]. In [[programmed cell death]], interphase is followed or preempted by [[apoptosis]].

== See also ==
* [[Prophase]]
* [[Prometaphase]]
* [[Metaphase]]
* [[Anaphase]]
* [[Telophase]]
* [[Cytokinesis]]
* [[Cytoskeleton]]

== Interphase (Materials) ==
The transition region between two materials. For example between the [[Fiber|fibre]] and matrix of a [[composite material]].

== References ==
{{reflist}}
{{cell cycle}}

[[Category:Mitosis]]
[[Category:Cell biology]]