Editing Cell growth (section)

{{short description|Increase of the total mass of the cancer cells}}
[[File:Cell proliferation.jpg|thumb|Cell division, growth & proliferation]]
{{TopicTOC-Biology}}
'''Cell growth''' refers to an increase in the total [[mass]] of a [[cell (biology)|cell]], including both [[cytoplasm]]ic, [[cell nucleus|nuclear]] and [[organelle]] volume.<ref name="ConlonRaff1999">{{cite journal|last1=Conlon|first1=Ian|last2=Raff|first2=Martin|title=Size Control in Animal Development|journal=Cell|volume=96|issue=2|year=1999|pages=235–244|issn=0092-8674|doi=10.1016/S0092-8674(00)80563-2|pmid=9988218|s2cid=15738174|doi-access=free}}</ref> Cell growth occurs when the overall rate of cellular [[biosynthesis]] (production of [[biomolecules]] or anabolism) is greater than the overall rate of cellular degradation (the destruction of [[biomolecules]] via the [[proteasome]], [[lysosome]] or [[autophagy]], or catabolism).<ref name="GrewalEdgar2003">{{cite journal|last1=Grewal|first1=Savraj S|last2=Edgar|first2=Bruce A|journal=Journal of Biology|title=Controlling cell division in yeast and animals: does size matter?|volume=2|issue=1|year=2003|pages=5|issn=1475-4924|doi=10.1186/1475-4924-2-5|pmid=12733996|pmc=156596|doi-access=free}}</ref><ref name="Neufeldde la Cruz1998">{{cite journal|last1=Neufeld|first1=Thomas P|last2=de la Cruz|first2=Aida Flor A|last3=Johnston|first3=Laura A|last4=Edgar|first4=Bruce A|title=Coordination of Growth and Cell Division in the Drosophila Wing|journal=Cell|volume=93|issue=7|year=1998|pages=1183–1193|issn=0092-8674|doi=10.1016/S0092-8674(00)81462-2|pmid=9657151|s2cid=14608744|doi-access=free}}</ref><ref name="Thompson">{{cite journal|last1=Thompson|first1=Barry J.|author-link=Barry James Thompson|year=2010|title=Developmental control of cell growth and division in Drosophila|journal=Current Opinion in Cell Biology|volume=22|issue=6|pages=788–794|doi=10.1016/j.ceb.2010.08.018|pmid=20833011}}</ref>

Cell growth is not to be confused with [[cell division]] or the [[cell cycle]], which are distinct processes that can occur alongside cell growth during the process of [[cell proliferation]], where a cell, known as the mother cell, grows and divides to produce two [[daughter cell]]s.<ref name="ConlonRaff1999"/> Importantly, cell growth and [[cell division]] can also occur independently of one another. During early [[embryonic development]] ([[cleavage (embryo)|cleavage]] of the [[zygote]] to form a [[morula]] and [[blastoderm]]), [[cell divisions]] occur repeatedly without cell growth. Conversely, some cells can grow without [[cell division]] or without any progression of the [[cell cycle]], such as growth of [[neurons]] during [[axon]]al pathfinding in [[nervous system]] development.

[[File:The Biological bulletin (20189537288).jpg|thumb|Cell division without cell growth during embryonic cleavage]]

In [[multicellular]] organisms, [[tissue growth]] rarely occurs solely through cell growth without [[cell division]], but most often occurs through [[cell proliferation]].<ref name="ConlonRaff1999"/> This is because a single cell with only one copy of the [[genome]] in the [[cell nucleus]] can perform [[biosynthesis]] and thus undergo cell growth at only half the rate of two cells. Hence, two cells grow (accumulate mass) at twice the rate of a single cell, and four cells grow at 4-times the rate of a single cell. This principle leads to an [[exponential growth|exponential]] increase of [[tissue growth]] rate (mass accumulation) during cell proliferation, owing to the [[exponential growth|exponential]] increase in cell number.

Cell size depends on both cell growth and [[cell division]], with a disproportionate increase in the rate of cell growth leading to production of larger cells and a disproportionate increase in the rate of cell division leading to production of many smaller cells. [[Cell proliferation]] typically involves balanced cell growth and [[cell division]] rates that maintain a roughly constant cell size in the exponentially proliferating population of cells.

Some special cells can grow to very large sizes via an unusual [[Endoreduplication|endoreplication]] cell cycle in which the [[genome]] is replicated during [[S-phase]] but there is no subsequent mitosis ([[M-phase]]) or cell division ([[cytokinesis]]). These large [[Endoreduplication|endoreplicating]] cells have many copies of the [[genome]], so are highly [[polyploid]].

[[Oocyte]]s can be unusually large cells in species for which embryonic development takes place away from the mother's body within an egg that is laid externally. The large size of some eggs can be achieved either by pumping in cytosolic components from adjacent cells through cytoplasmic bridges named ring canals (''[[Drosophila]]'') or by internalisation of nutrient storage granules (yolk granules) by [[endocytosis]] ([[frog]]s).