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A gamete (; , ultimately ) is a haploid cell that fuses with another haploid cell during in that reproduce sexually. Gametes are an organism's reproductive cells, also referred to as sex cells. In species that produce two morphologically distinct types of gametes, and in which each individual produces only one type, a is any individual that produces the larger type of gamete—called an — and a produces the smaller type—called a . Sperm cells or spermatozoa are small and motile due to the flagellum, a tail-shaped structure that allows the cell to propel and move. In contrast, each egg cell or ovum is relatively large and non-motile. In short a gamete is an egg cell (female gamete) or a sperm (male gamete). In animals, ova mature in the ovaries of females and sperm develop in the testes of males. During fertilization, a spermatozoon and ovum unite to form a new . Gametes carry half the genetic information of an individual, one of each type, and are created through , in which a germ cell undergoes two fissions, resulting in the production of four gametes. In biology, the type of gamete an organism produces determines the classification of its sex.

This is an example of or , the condition in which females and males produce gametes of different sizes (this is the case in humans; the human ovum has approximately 100,000 times the volume of a single human sperm cell). In contrast, is the state of gametes from both sexes being the same size and shape, and given arbitrary designators for . The name gamete was introduced by the German cytologist Eduard Strasburger. Male and female gametes set the basis for the sexual roles and sexual selection.

(2019). 9781108499859, Cambridge University Press. .

is the process of female gamete formation in animals. This process involves (including meiotic recombination) occurring in the diploid primary to produce the haploid . is the process of male gamete formation in animals. This process also involves meiosis occurring in the diploid primary to produce the haploid .


Evolution
It is generally accepted that is the ancestral state from which evolved, although its evolution has left no fossil records.
(2022). 9780080919874, Academic Press. .
also evolved from isogamy through anisogamy.
9789325990227, Vikas Publishing House. .
(2022). 9780674031166, Harvard University Press. .
There are almost invariably only two gamete types, all analyses showing that intermediate gamete sizes are eliminated due to selection.
(2013). 9783034862738, Birkhäuser. .
Intermediate sized gametes do not have the same advantages as small or large ones;
(2013). 9780191647017, OUP Oxford. .
they do worse than small ones in mobility and numbers, and worse than large ones in supply.


Dissimilarity
In contrast to a gamete, a diploid of an individual contains one copy of the set from the sperm and one copy of the chromosome set from the egg cell. Consequently, the cells of the offspring have genes potentially capable of expressing characteristics of both the father and the mother, subject to whether they are dominant or recessive. A gamete's chromosomes are not exact duplicates of either of the sets of chromosomes carried in the diploid chromosomes but a mixture of the two.


Sex determination in mammals and birds
and most mammals use the XY sex-determination system in which a normal ovum can carry only an whereas a sperm may carry either an X or a Y, while a non-normal sperm cell can end up carrying either no sex-defining chromosomes, an XY pair, or an XX pair; thus the male sperm determines the of any resulting . If the zygote has two X chromosomes it will develop into a female, if it has an X and a Y chromosome, it will develop into a male.
(2009). 9781429223188, Macmillan. .

For birds, the female ovum determines the sex of the offspring, through the ZW sex-determination system.


Artificial gametes
Artificial gametes, also known as In vitro derived gametes (IVD), stem cell-derived gametes (SCDGs), and In vitro generated gametes (IVG), are gametes derived from . The use of such artificial gametes would QUOTE: "necessarily require IVF techniques". Research shows that artificial gametes may be a reproductive technique for same-sex male couples, although a would still be required for the gestation period. Women who have passed may be able to produce eggs and bear genetically related children with artificial gametes. Robert Sparrow wrote, in the Journal of Medical Ethics, that embryos derived from artificial gametes could be used to derive new gametes and this process could be repeated to create multiple human generations in the laboratory. This technique could be used to create for medical applications and for studying the heredity of . Additionally, this technique could be used for human enhancement by selectively breeding for a desired genome or by using technology to create enhancements that have not arisen in nature.


Plants
which reproduce sexually also produce gametes. However, since plants have a life cycle involving alternation of diploid and haploid generations some differences exist. Plants use to produce spores that develop into multicellular haploid which produce gametes by mitosis. The sperm are formed in an organ known as the and the egg cells in a flask-shaped organ called the . In , the female gametophyte is produced inside the within the ovary of the flower. When mature, the haploid gametophyte produces female gametes which are ready for fertilization. The male gametophyte is produced inside a grain within the . When a pollen grain lands on a mature stigma of a flower it germinates to form a that grows down the style into the ovary of the flower and then into the ovule. The pollen then produces sperm by mitosis and releases them for fertilization.


See also


Notes and references
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