[[id:Selsel tumbuhan ]]???▼[[Image:Plant cell structure svg.svg|thumb|323px|Struktur sel tumbuhan]]
'''Sel tumbuhan''' merupakan sel [[eukariot]] yang berbeza dalam beberapa ciri utama berbanding sel bagi organisma eukariot yang lain. Perbezaannya termasuk:
* [[Vacuole]] pusat yang besar, isipadu berisi air diselitupi selaput yang dikenali sebagai ''[[tonoplas]]''<ref name=JRaven>JA Raven (1997) The vacuole: a cost-benefit analysis. Advances in Botanical Research 25, 59–86</ref><ref name=Leigh&Sanders>RA Leigh and D Sanders (1997) Advances in Botanical Research, Vol 25: The Plant
Vacuole. Academic Press, California and London. ISBN 0 12 441870-8</ref> yang mengekalkan [[turgor]] sel, mengawal pergerakan [[molekul]] antaras [[cytosol]] dan [[plant sap|sap]], menyimpan bahan berguna dan menyingkir protin buangan dan [[organel]].
* [[Dinding sel]] terdiri daripada selulosa dan hemiselulosa, [[pektin]] dan dalam kebanyakan kes [[lignin]], yang dirembes oleh [[protoplast]] di luar [[selaput sel]]. Ini berbeza dengan dinding sel fungi (yang terhasil oleh [[chitin]]), dan bagi [[bakteria]], yang dibuat dari [[peptidoglikan]].
* Laluan sel-sel komunikasi yang khusus dikenali sebagai [[plasmodesmata]],<ref name=Oparka>Oparka, KJ (1993) Signalling via plasmodesmata-the neglected pathway. Seminars in Cell Biogy 4, 131–138</ref> melalui liang pada dinding sel utama di mana [[plasmalema]] dan [[retikulum endoplasma]] pada <ref name=Hepler>Hepler, PK (1982) Endoplasmic reticulum in the formation of the cell plate and plasmodesmata. Protoplasma 111, 121–133</ref> sel bersebelahan berterusan.
Plastids , yang paling terkenal sebagai kloroplas yang mengandungi klorofil pigmen berwarna hijau yang digunakan untuk menyerap cahaya matahari dan digunakan oleh tumbuhan untuk membuat makanan sendiri dalam proses yang dikenali sebagai fotosintesis . Jenis lain plastid amyloplasts , khusus untuk kanji penyimpanan, elaioplasts yang khusus bagi lemak penyimpanan, dan chromoplasts khusus untuk sintesis dan penyimpanan pigmen . Seperti dalam mitokondria , yang mempunyai genom pengekodan 37 gen, [5] plastids mempunyai mereka sendiri genom kira-kira 100-120 gen unik [6] , adalah dianggap, timbul sebagai prokariot endosymbionts hidup dalam sel-sel awal eukaryotik moyang tumbuhan tanah dan alga . [7]
* [[Plastid]], paling terkenal sebagai [[kloroplas]], yang mengandungi [[klorofil]] pigmen berwarna hijau yang digunakan untuk menyerap cahaya matahari dan digunakan oleh tumbuhan untuk membuat makanan sendiri dalam proses yang dikenali sebagai fotosintesis . Jenis lain plastid adalah amiloplas, khusus bagi penyimpanan kanji, [[elaioplas]] khusus bagi penyimpanan lemak, dan [[kromoplas]] khusus bagi sintesis dan penyimpanan [[pigmen]]. Sebagaimana bagi [[mitokondria]], yang memiliki pengkod genom 37 gen,<ref name=Andersonetal1981>Anderson S, Bankier AT, et al. (1981) Jujukan dan aturan genom mitokondria manusia. Nature 290, 4–65</ref> plastid memiliki genom mereka sendiri sekitar 100–120 gen unik<ref>L Cui, N Veeraraghavan, et al. (2006) ChloroplastDB: the chloroplast genome database. Nucleic Acids Research, 34, D692-696</ref> dan, ia dianggap, muncul ketika [[endosymbiont]] [[prokariot]] living in the cells of an early [[eukaryote|eukaryotic]] ancestor of the [[embryophyte|land plants]] and [[algae]].<ref name=Margulis>L. Margulis (1970) Origin of eukaryotic cells. Yale University Press, New Haven</ref>
* Cell division by construction of a [[phragmoplast]] as a template for building a [[cell plate]] late in [[cytokinesis]] is characteristic of land plants and a few groups of algae, notably the [[Charophyta|Charophytes]]<ref name=Lewis2004>Lewis, LA, McCourt, RM (2004) Green algae and the origin of land plants. American Journal of Botany 91, 1535–1556</ref> and the Order [[Trentepohliales]]<ref name=LopezBautista>López-Bautista, JM, Waters, DA and Chapman, RL (2003) Phragmoplastin, green algae and the evolution of cytokinesis. International Journal of Systematic and Evolutionary Microbiology 53, 1715–1718</ref>
* The [[sperm]] of [[bryophyte]]s and [[pteridophytes]] have [[flagella]]e similar to those in animals,<ref name=Manton>Manton, I. and Clarke, B. (1952) An [[electron microscope]] study of the [[spermatozoid]] of ''[[Sphagnum]]''. Journal of Experimental Botany 3, 265–275</ref><ref name=Paolillo>D.J. Paolillo, Jr. (1967) On the structure of the [[axoneme]] in flagella of ''[[Polytrichaceae|Polytrichum juniperinum]]''. Transactions of the American Microscopical Society, 86, 428–433</ref> but higher plants, (including [[gymnospermae|Gymnosperms]] and [[flowering plant]]s) lack the [[flagellum|flagella]]e and [[centriole]]s<ref name=raven>PH Raven , Evert RF, Eichhorm SE (1999) Biology of Plants, 6th edition. WH Freeman, New York</ref> that are present in [[Eukaryote#Animal cell|animal cell]]s.
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==Cell types==
* [[Parenchyma|Parenchyma cells]] are living cells that have diverse functions ranging from storage and support to [[photosynthesis]] and phloem loading ([[transfer cells]]). Apart from the xylem and phloem in their vascular bundles, leaves are composed mainly of parenchyma cells. Some parenchyma cells, as in the epidermis, are specialized for light penetration and focusing or regulation of [[gas exchange]], but others are among the least specialized cells in plant tissue, and may remain [[totipotent]], capable of dividing to produce new populations of undifferentiated cells, throughout their lives. Parenchyma cells have thin, permeable primary walls enabling the transport of small molecules between them, and their cytoplasm is responsible for a wide range of biochemical functions such as [[nectar]] [[secretion]], or the manufacture of [[secondary metabolite|secondary products]] that discourage [[herbivory]]. Parenchyma cells that contain many chloroplasts and are concerned primarily with photosynthesis are called [[chlorenchyma]] cells. Others, such as the majority of the parenchyma cells in [[potato]] [[tubers]] and the [[seed]] [[cotyledons]] of [[legumes]], have a storage function.
* [[Ground tissue|Collenchyma cells]] – collenchyma cells are alive at maturity and have only a primary wall. These cells mature from meristem derivatives that initially resemble parenchyma, but differences quickly become apparent. Plastids do not develop, and the secretory apparatus (ER and Golgi) proliferates to secrete additional primary wall. The wall is most commonly thickest at the corners, where three or more cells come in contact, and thinnest where only two cells come in contact, though other arrangements of the wall thickening are possible.<ref name=Cutter/>
[[Pectin]] and [[hemicellulose]] are the dominant constituents of collenchyma cell walls of [[dicotyledon]] [[angiosperm]]s, which may contain as little as 20% of cellulose in ''[[Petasites]]''.<ref name=Roelofsen>PA Roelofsen (1959) 'The plant cell wall.' ''Handbuch fur Pflanzenanatomie''. Band III. Gebrüder Borntraeger, Berlin</ref> Collenchyma cells are typically quite elongated, and may divide transversely to give a septate appearance. The role of this cell type is to support the plant in axes still growing in length, and to confer flexibility and tensile strength on tissues. The primary wall lacks lignin that would make it tough and rigid, so this cell type provides what could be called plastic support – support that can hold a young stem or petiole into the air, but in cells that can be stretched as the cells around them elongate. Stretchable support (without elastic snap-back) is a good way to describe what collenchyma does. Parts of the strings in celery are collenchyma.
* [[Ground tissue|Sclerenchyma cells]] – Sclerenchyma cells (from the Greek '''skleros''', ''hard'') are hard and tough cells with a function in mechanical support. They are of two broad types – [[sclereid]]s or stone cells and [[fibre]]s. The cells develop an extensive secondary cell wall that is laid down on the inside of the [[primary cell wall]]. The secondary wall is impregnated with [[lignin]], making it hard and impermeable to water. Thus, these cells cannot survive for long' as they cannot exchange sufficient material to maintain active metabolism. Sclerenchyma cells are typically dead at functional maturity, and the cytoplasm is missing, leaving an empty central cavity.
Functions for sclereid cells (hard cells that give leaves or fruits a gritty texture) include discouraging herbivory, by damaging digestive passages in small insect larval stages, and physical protection (a solid tissue of hard sclereid cells form the pit wall in a peach and many other fruits). Functions of fibres include provision of load-bearing support and tensile strength to the leaves and stems of herbaceous plants.<ref name=Cutter>EG Cutter (1977) Plant Anatomy Part 1. Cells and Tissues. Edward Arnold, London</ref> Sclerenchyma fibres are not involved in conduction, either of water and nutrients (as in the [[xylem]]) or of carbon compounds (as in the [[phloem]]), but it is likely that they may have evolved as modifications of xylem and phloem initials in early land plants.
==Tissue types==
[[Image:Arabidopsis-epiderm-conidiospore-hyaloperonospora-parasitica.jpg|thumb|right|cells of ''[[Arabidopsis thaliana]]'' [[Epidermis (botany)|epidermis]]]]
The major classes of cells differentiate from undifferentiated [[meristem]]atic cells (analogous to the stem cells of animals) to form the tissue structures of [[root]]s, [[plant stem|stems]], [[leaf|leaves]], [[flower]]s, and reproductive structures.
[[Xylem]] cells<ref name=Tyree>MT Tyree; MH Zimmermann (2003) Xylem structure and the ascent of sap, 2nd edition, Springer-Verlag, New York USA</ref> are elongated cells with lignified secondary thickening of the cell walls. Xylem cells are specialised for conduction of water, and first appeared in plants during their transition to land in the [[Silurian]] period more than 425 million years ago (see ''[[Cooksonia]]''). The possession of xylem defines the [[vascular plants]] or [[Tracheophyte]]s. Xylem tracheids are pointed, elongated xylem cells, the simplest of which have continuous primary cell walls and lignified secondary wall thickenings in the form of rings, hoops, or reticulate networks. More complex tracheids with valve-like perforations called [[pit (botany)|bordered pits]] characterise the gymnosperms. The [[fern]]s and other [[pteridophyte]]s and the [[gymnosperm]]s have only xylem [[tracheid]]s, while the [[angiosperms]] also have [[vessel element|xylem vessel]]s. Vessel members are hollow xylem cells aligned end-to-end, without end walls that are assembled into long continuous tubes. The bryophytes lack true xylem cells, but their [[sporophyte]]s have a water-conducting tissue known as the hydrome that is composed of elongated cells of simpler construction.
[[Phloem]] is a specialised tissue for food conduction in higher plants. The conduction of food is a complex process that is carried in the plant with the help of special cell called phloem cells. These cells conduct inter- and intra-cellular fluid (food – proteins and other essential elements required by the plant for its metabolism) through the process of osmosis. This phenomenon is called ascent of sap in plants. Phloem consists of two cell types, the [[sieve tube element|sieve tubes]] and the intimately-associated [[companion cell]]s. The [[sieve tube element]]s lack [[cell nucleus|nuclei]] and [[ribosome]]s, and their metabolism and functions are regulated by the adjacent nucleate companion cells. Sieve tubes are joined end-to-end with perforate end-plates between known as ''[[sieve plate]]s'', which allow transport of photosynthate between the sieve elements. The companion cells, connected to the sieve tubes via [[plasmodesmata]], are responsible for loading the phloem with [[sugar]]s. The [[bryophyte]]s lack phloem, but [[moss]] [[sporophyte]]s have a simpler tissue with analogous function known as the leptome.
Plant [[Epidermis (botany)|epidermal cells]] are specialised parenchyma cells covering the external surfaces of leaves, stems and roots. The epidermal cells of aerial organs arise from the superficial layer of cells known as the ''tunica'' (L1 and L2 layers) that covers the plant [[meristem|shoot apex]],<ref name="Cutter"/> whereas the cortex and vascular tissues arise from innermost layer of the shoot apex known as the ''corpus'' (L3 layer). The epidermis of roots originates from the layer of cells immediately beneath the root cap.
The epidermis of all aerial organs, but not roots, is covered with a [[plant cuticle|cuticle]] made of the [[polyester]] [[cutin]] with a superficial layer of [[epicuticular wax|waxes]]. The epidermal cells of the primary shoot are thought to be the only plant cells with the biochemical capacity to synthesize cutin.<ref name="Kolattukudy 1996">Kolattukudy, PE (1996) Biosynthetic pathways of cutin and waxes, and their sensitivity to environmental stresses. In: Plant Cuticles. Ed. by G. Kerstiens, BIOS Scientific publishers Ltd., Oxford, pp 83–108</ref> Several cell types may be present in the epidermis. Notable among these are the stomatal guard cells, glandular and clothing hairs or [[trichome]]s, and the [[root hair]]s of primary roots. In the shoot epidermis of most plants, only the [[stomata|guard cells]] have chloroplasts.
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==Rujukan==
{{Reflist|2}}
== Pautan luar ==
*[http://www.smartymaps.com/map.php?s=plantEukaryote Parts of a plant cell]
{{DEFAULTSORT:Plant Cell}}
[[Kategori:Anatomi tumbuhan]]
[[Kategori:Biologi sel]]
[[ca:Cèl·lula vegetal]]
[[cs:Rostlinná buňka]]
[[et:Taimerakk]]
[[es:Célula vegetal]]
[[eu:Landare zelula]]
[[fr:Cellule végétale]]
[[gl:Célula vexetal]]
[[hi:संयंत्र सेल]]
[[it:Cellula vegetale]]
[[kn:ಸಸ್ಯ ಜೀವಕೋಶ]]
[[lv:Augu šūna]]
[[lt:Augalinė ląstelė]]
[[en:plant cell]]
[[nl:Plantaardige cel]]
[[no:Plantecelle]]
[[pl:Komórka roślinna]]
[[pt:Célula vegetal]]
[[ro:Celulă vegetală]]
[[simple:Plant cell]]
[[sk:Rastlinná bunka]]
[[sl:Rastlinska celica]]
[[sr:Биљна ћелија]]
[[sv:Växtcell]]
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