Gamete 12295 225716600 2008-07-15T01:35:13Z 12.149.39.84 /* Gametogenesis */ A '''gamete''' (from [[Ancient Greek]] ''γαμετης''; translated ''gamete'' = wife, ''gametes'' = husband) is a [[Cell_%28biology%29|cell]] that fuses with another gamete during [[fertilization]] (conception) in [[organism]]s that [[sexual reproduction|reproduce sexually]]. In species which produce two morphologically distinct types of gametes, and in which each individual produces only one type, a [[female]] is any individual which produces the larger type of gamete—called an [[ovum]] (or egg)—and a [[male]] produces the smaller tadpole-like type—called a [[sperm]]. This is an example of [[anisogamy]] or [[heterogamy]], the condition wherein females and males produce gametes of different sizes (this is the case in humans, the human ovum is approximately 20 times larger than the human sperm cell). In contrast, [[isogamy]] is the state of gametes from both sexes being the same size. The name gamete was introduced by the [[Austria]]n biologist [[Gregor Mendel]]. Gametes carry half the [[genetic information]] of an individual, one [[chromosome]] of each type. In [[humans]] an ovum can only carry [[X chromosome]] (of the X and [[Y chromosomes]]) whereas a sperm can carry either an X or a Y, hence, it has been suggested that males have the control of the [[gender]] of any resulting [[zygote]] as the [[genotype]] of the sex-determining chromosomes of a male must be XY and a female XX. In other words, due to the presence of the Y chromosome exclusively in the sperm, it is that gamete alone which can determine that an offspring will be a male. ==Gametogenesis== {{Main|Gametogenesis}} [[Image:Gray7.png|thumb|Scheme showing analogies in the process of maturation of the ovum and the development of the spermatids.]] The production of gametes is termed ''gametogenesis'', during which phase [[gametocyte]]s divide by [[meiosis]] into gametes. Meiosis reduces the number of sets of chromosomes from two to one (i.e., produces haploid gametes from diploid gametocytes). Organs that produce gametes are called [[gonad]]s in animals, and [[archegonium| archegonia]] or [[antheridium|antheridia]] in plants. ==Gamete cycle== A gamete of one generation ultimately creates a gametes in the next generation, but still keeping the same quantity of genetic information. Gametes are [[haploid]] cells; that is, they contain one half a complete set of [[chromosome]]s (the actual number varies from species to species). When two gametes fuse (in animals typically involving a sperm and an egg), they form a ''[[zygote]]''—a cell that has two complete sets of chromosomes and therefore is [[diploid]]. The zygote receives one set of chromosomes from each of the two gametes through the fusion of the two gamete [[cell nucleus|nuclei]]. After multiple [[cell division]]s and [[cellular differentiation]], a zygote [[developmental biology|develops]], first into an [[embryo]], and ultimately into a mature individual capable of producing gametes. ==Dissimilarity== In contrast to a gamete, the diploid [[somatic cell]]s of an individual contain one copy of the chromosome set from the sperm and one copy of the chromosome set from the egg; that is, the cells of the offspring have genes expressing characteristics of both the ''father'' and the ''mother''. A gamete's chromosomes are not exact duplicates of either of the sets of chromosomes carried in the somatic cells of the individual that produced the gametes. They can be ''hybrids'' produced through [[Chromosomal crossover| crossover]] (a form of [[genetic recombination]]) of chromosomes, which takes place in meiosis. This hybridization has a random element, and the chromosomes tend to be a little different in every gamete that an individual produces. This recombination and the fact that the two chromosome sets ultimately come from either a grandmother or a grandfather on each parental side account for the [[genetics|genetic]] dissimilarity of [[Family|siblings]]. [[Category:Classical genetics]] [[Category:Germ cells]] [[Category:Evolution]] [[Category:Reproductive system]] [[cs:Pohlavní buňka]] [[da:Gamet]] [[de:Gamet]] [[es:Gameto]] [[eo:Gameto]] [[fr:Gamète]] [[it:Gamete]] [[he:תא רבייה]] [[lt:Gameta]] [[mk:Гамета]] [[nl:Gameet]] [[ja:配偶子]] [[no:Kjønnscelle]] [[pl:Gameta]] [[pt:Gameta]] [[ru:Гамета]] [[sk:Pohlavná bunka]] [[sv:Könscell]] [[th:แกมีต]] [[zh:生殖细胞]]