Zygote: Difference between revisions
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A '''zygote''' (from [[Greek language|Greek]] ζυγωτός ''zygōtos'' "joined" or "yoked", from ζυγοῦν ''zygoun'' "to join" or "to yoke"),<ref>{{cite web| url=http://www.myetymology.com/english/zygote.html |title=English etymology of zygote |work=myetymology.com}}</ref> or '''zygocyte''', is the initial [[cell (biology)|cell]] formed when two [[gamete]] cells are joined by means of [[sexual reproduction]]. In multicellular organisms, it is the earliest developmental stage of the [[embryo]]. In single-celled organisms, the zygote divides to produce offspring, usually through [[meiosis]]. |
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A zygote is always synthesized from the union of two gametes, and constitutes the first stage in a unique organism's [[developmental biology|development]]. Zygotes are usually produced by a [[fertilization]] event between two [[ploidy|haploid]] cells—an [[ovum]] ([[female]] gamete) and a [[sperm]] cell ([[male]] gamete)—which combine to form the single [[ploidy|diploid]] cell. Such zygotes contain [[DNA]] derived from both the parents, and this provides all the genetic information necessary to form a new individual. |
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==Plants== |
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In [[embryophyte|land plants]], the zygote is formed within a chamber called the [[archegonium]]. In seedless plants, the archegonium is usually flask-shaped, with a long hollow neck through which the sperm cell enters. As the zygote divides and grows, it does so inside the archegonium. |
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==Animals== |
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In animal development, the term ''zygote'' is also used more loosely to refer to the group of cells formed by the first few cell divisions, although this is properly referred to as a [[morula]].<ref>Neas, John F. [http://cwx.prenhall.com/bookbind/pubbooks/martini10/chapter28/custom3/deluxe-content.html "Human Development"]. ''Embryology Atlas''</ref> |
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In [[mammalian reproduction]], after fertilization has taken place the zygote travels down the [[fallopian tube]], while [[cell division|dividing to form more cells]]<ref>O’Reilly, Deirdre. "[http://www.nlm.nih.gov/medlineplus/ency/article/002398.htm Fetal development]". ''[[MedlinePlus|MedlinePlus Medical Encyclopedia]]'' (2007-10-19). Retrieved 2009-02-15.</ref> without the zygote actually increasing in size. This cell division is [[mitosis|mitotic]], and is known as ''[[cleavage (embryo)|cleavage]]''.<ref>Klossner, N. Jayne and Hatfield, Nancy. ''[http://books.google.com/books?id=rAOTF7g6tbgC&pg=PA107&dq=zygote+cleavage+blastocyst&as_brr=3&ei=mJaYSbj2CZjEM-Hc9KQJ Introductory Maternity & Pediatric Nursing,]'' p. 107 ([[Lippincott Williams & Wilkins]], 2006).</ref> All mammals go through the zygote stage of life. Mammalian zygotes eventually develop into a [[blastocyst]], after which they are more generally termed an embryo, and then a [[fetus]]. |
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| ⚫ | A human zygote exists for about four days, and becomes a [[blastocyst]] on the fifth day.<ref>Blackburn, Susan. ''[http://books.google.com/books?id=2y6zOSQcn14C&pg=PA77&dq=zygote&num=100&as_brr=3&ei=lwCTSf_4EoTOlQT4zdClAg#PPA80,M1 Maternal, Fetal, & Neonatal Physiology,]'' p. 80 (Elsevier Health Sciences 2007).</ref> |
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==In other species== |
==In other species== |
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A '''biparental zygote''' is a [[Chlamydomonas]] (a kind of [[algae]]) zygote that contains [[chloroplast]] DNA ([[cpDNA]]) from both parents. |
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A '''bip |
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==See also== |
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* [[Proembryo]] |
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* [[Zygote intrafallopian transfer]] |
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==References== |
==References== |
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{{reflist}} |
{{reflist}} |
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{{succession box|title=[[Stages of human development]]|before=[[Oocyte]] + [[Sperm cell]]| |
{{succession box|title=[[Stages of human development]]|before=[[Oocyte]] + [[Sperm cell]]|after=[[Embryo]]|years=Zygote}} |
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{{S-end}} |
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{{Embryology}} |
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[[Category:Developmental biology]] |
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[[Category:Reproductive system]] |
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[[als:Zygote]] |
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[[ar:لاقحة]] |
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[[az:Ziqot]] |
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[[be:Зігота]] |
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[[be-x-old:Зыгота]] |
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[[ca:Zigot]] |
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[[cs:Zygota]] |
[[cs:Zygota]] |
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[[cy:Sygot]] |
[[cy:Sygot]] |
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Revision as of 21:39, 4 October 2012
A zygote (from Greek ζυγωτός zygōtos "joined" or "yoked", from ζυγοῦν zygoun "to join" or "to yoke"),[1] or zygocyte, is the initial cell formed when two gamete cells are joined by means of sexual reproduction. In multicellular organisms, it is the earliest developmental stage of the embryo. In single-celled organisms, the zygote divides to produce offspring, usually through meiosis.
A zygote is always synthesized from the union of two gametes, and constitutes the first stage in a unique organism's development. Zygotes are usually produced by a fertilization event between two haploid cells—an ovum (female gamete) and a sperm cell (male gamete)—which combine to form the single diploid cell. Such zygotes contain DNA derived from both the parents, and this provides all the genetic information necessary to form a new individual.
Plants
In land plants, the zygote is formed within a chamber called the archegonium. In seedless plants, the archegonium is usually flask-shaped, with a long hollow neck through which the sperm cell enters. As the zygote divides and grows, it does so inside the archegonium.
Animals
In animal development, the term zygote is also used more loosely to refer to the group of cells formed by the first few cell divisions, although this is properly referred to as a morula.[2]
In mammalian reproduction, after fertilization has taken place the zygote travels down the fallopian tube, while dividing to form more cells[3] without the zygote actually increasing in size. This cell division is mitotic, and is known as cleavage.[4] All mammals go through the zygote stage of life. Mammalian zygotes eventually develop into a blastocyst, after which they are more generally termed an embryo, and then a fetus.
A human zygote exists for about four days, and becomes a blastocyst on the fifth day.[5]
In other species
A biparental zygote is a Chlamydomonas (a kind of algae) zygote that contains chloroplast DNA (cpDNA) from both parents.
See also
References
- ^ "English etymology of zygote". myetymology.com.
- ^ Neas, John F. "Human Development". Embryology Atlas
- ^ O’Reilly, Deirdre. "Fetal development". MedlinePlus Medical Encyclopedia (2007-10-19). Retrieved 2009-02-15.
- ^ Klossner, N. Jayne and Hatfield, Nancy. Introductory Maternity & Pediatric Nursing, p. 107 (Lippincott Williams & Wilkins, 2006).
- ^ Blackburn, Susan. Maternal, Fetal, & Neonatal Physiology, p. 80 (Elsevier Health Sciences 2007).