What is Plant cell?
[[File:Simple diagram of plant cell (en).svg|thumb|280px|'''A plant cell diagram.''' ]] [[File:Plant cell structure-en.svg|thumb|280px|Plant cell structure]] Like all [[organism]]s, plants have [[cell]]s. Plant cells have a [[nucleus]] with [[chromosomes]] and [[DNA]], and they have [[mitochondria]]. Those are common to all eukaryotic cells. But in some ways they are different from animal cells and the cells of other [[eukaryotes]]. * They have [[cell wall]]s composed of [[cellulose]] and some other compounds. [[Pectin]], and sometimes [[lignin]], is [[secretion|secreted]] on the outside of the [[cell membrane]]. This is different from the cell walls of [[fungus|fungi]] (which are made of [[chitin]]), and of [[bacteria]] (which are made of [[peptidoglycan]]). The cell wall gives the cell a definite shape. * There are special cell-to-cell communication pathways known as [[plasmodesma]]ta.<ref name=Oparka>Oparka K.J. 1993. Signalling via plasmodesmata - the neglected pathway. ''Seminars in Cell Biology'' '''4''', 131–138.</ref> These are pores in the cell wall through which the cell content of adjacent cells (including [[endoplasmic reticulum]]) are continuous.<ref name=Hepler>Hepler P.K. 1982. Endoplasmic reticulum in the formation of the cell plate and plasmodesmata. ''Protoplasma'' '''111''', 121–133.</ref> * They have [[plastid]]s. The most notable are the [[chloroplast]]s, which contain [[chlorophyll]]. This green-colored [[pigment]] absorbs [[sunlight]], and allows the plant to make its own food by [[photosynthesis]]. Other types of plastids are the [[amyloplast]]s, which store [[starch]], [[elaioplast]]s for [[fat]] storage, and [[chromoplast]]s for making and storing [[pigment]]s. Like [[mitochondria]], plastids have their own [[genome]]s of about 100–120 unique [[gene]]s.<ref>L. Cui ''et al'' 2006. ChloroplastDB: the chloroplast genome database. ''Nucleic Acids Research'', '''34''', D692-696.</ref> It is thought they started as [[prokaryote|prokaryotic]] [[endosymbiont]]s living in the cells of an early