Female

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The symbol of the Roman goddess Venus is commonly used to represent the female sex. It also stands for the planet Venus and is the alchemical symbol for copper. Venus symbol.svg
The symbol of the Roman goddess Venus is commonly used to represent the female sex. It also stands for the planet Venus and is the alchemical symbol for copper.

Female (symbol: ♀) is the sex of an organism, or a part of an organism, that produces non-mobile ova (egg cells). [1] [2] [3] Barring rare medical conditions, most female mammals, including female humans, have two X chromosomes. Female characteristics vary between different species with some species containing more well defined female characteristics, such as the presence of pronounced mammary glands. There is no single genetic mechanism behind sex differences in different species and the existence of two sexes seems to have evolved multiple times independently in different evolutionary lineages. [4]

Contents

The word female comes from the Latin femella, the diminutive form of femina, meaning "woman"; [5] it is not etymologically related to the word male. [6] [7] Female can also be used to refer to gender.

Defining characteristics

Females produce ova, the larger gametes in a heterogamous reproduction system, while the smaller and usually motile gamete, the spermatozoon, is produced by the male. [1] [8] A female cannot reproduce sexually without access to the gametes of a male, and vice versa, but in some species females can reproduce by themselves asexually, for example via parthenogenesis. [9]

There is no single genetic mechanism behind sex differences in different species and the existence of two sexes seems to have evolved multiple times independently in different evolutionary lineages. [10] Patterns of sexual reproduction include:

Other than the defining difference in the type of gamete produced, differences between males and females in one lineage cannot always be predicted by differences in another. The concept is not limited to animals; egg cells are produced by chytrids, diatoms, water moulds and land plants, among others. In land plants, female and male designate not only the egg- and sperm-producing organisms and structures, but also the structures of the sporophytes that give rise to male and female plants.[ citation needed ]

Mammalian female

Photograph of an adult female human, with an adult male for comparison. Note that both models have partially shaved body hair; e.g. clean-shaven pubic regions. Anterior view of human female and male, with labels 2.png
Photograph of an adult female human, with an adult male for comparison. Note that both models have partially shaved body hair; e.g. clean-shaven pubic regions.

A distinguishing characteristic of the class Mammalia is the presence of mammary glands. The mammary glands are modified sweat glands that produce milk, which is used to feed the young for some time after birth. Only mammals produce milk. Mammary glands are most obvious in humans, as the female human body stores large amounts of fatty tissue near the nipples, resulting in prominent breasts. Mammary glands are present in all mammals, although they are seldom used by the males of the species. [13]

Most mammalian females have two copies of the X chromosome as opposed to males which have only one X and one smaller Y chromosome; some mammals, such as the platypus, have different combinations. [14] [15] To compensate for the difference in size, one of the female's X chromosomes is randomly inactivated in each cell of placental mammals while the paternally derived X is inactivated in marsupials. In birds and some reptiles, by contrast, it is the female which is heterozygous and carries a Z and a W chromosome whilst the male carries two Z chromosomes. Intersex conditions can also give rise to other combinations, such as XO or XXX in mammals, which are still considered as female so long as they do not contain a Y chromosome, except for specific cases of mutations in the genes of XY individuals while in the womb. However, these conditions frequently result in sterility.[ citation needed ]

Mammalian females bear live young, with the exception of monotreme females, which lay eggs. [16] Some non-mammalian species, such as guppies, have analogous reproductive structures; and some other non-mammals, such as sharks, whose eggs hatch inside their bodies, also have the appearance of bearing live young.[ citation needed ]

Etymology and usage

"faemnan," an Old English word for 'female' Beowulf - faemnan.jpg
"fæmnan," an Old English word for 'female'

The word female comes from the Latin femella, the diminutive form of femina, meaning "woman"; it is not etymologically related to the word male, but in the late 14th century the spelling was altered in English to parallel the spelling of male. [6] [7] Female can refer to either sex or gender [17] [18] or a shape of connectors. [19] [20]

Symbol

The symbol ♀ (Unicode: U+2640 Alt codes: Alt+12), a circle with a small cross underneath, is commonly used to represent females. Joseph Justus Scaliger once speculated that the symbol was associated with Venus, goddess of beauty because it resembles a bronze mirror with a handle, [21] but modern scholars consider that fanciful, and the most established view is that the female and male symbols derive from contractions in Greek script of the Greek names of the planets Thouros (Mars) and Phosphoros (Venus). [22] [23]

Sex determination

The sex of a particular organism may be determined by a number of factors. These may be genetic or environmental, or may naturally change during the course of an organism's life. Although most species have only two sexes (either male or female), [24] hermaphroditic animals have both male and female reproductive organs.[ citation needed ]

Genetic determination

The sex of most mammals, including humans, is genetically determined by the XY sex-determination system where males have X and Y (as opposed to X and X) sex chromosomes. During reproduction, the male contributes either an X sperm or a Y sperm, while the female always contributes an X egg. A Y sperm and an X egg produce a male, while an X sperm and an X egg produce a female. The ZW sex-determination system, where males have ZZ (as opposed to ZW) sex chromosomes, is found in birds, reptiles and some insects and other organisms. Members of Hymenoptera, such as ants and bees, are determined by haplodiploidy, where most males are haploid and females and some sterile males are diploid. [ citation needed ]

Environmental determination

The young of some species develop into one sex or the other depending on local environmental conditions, e.g. many crocodilians' sex is influenced by the temperature of their eggs. Other species (such as the goby) can transform, as adults, from one sex to the other in response to local reproductive conditions (such as a brief shortage of males). [25]

See also

Related Research Articles

Asexual reproduction Reproduction without a sexual process

Asexual reproduction is a type of reproduction that does not involve the fusion of gametes or change in the number of chromosomes. The offspring that arise by asexual reproduction from either unicellular or multicellular organisms inherit the full set of genes of their single parent. Asexual reproduction is the primary form of reproduction for single-celled organisms such as archaea and bacteria. Many eukaryotic organisms including plants, animals, and fungi can also reproduce asexually. In vertebrates, the most common form of asexual reproduction is parthenogenesis, which is typically used as an alternative to sexual reproduction in times when reproductive opportunities are limited.

Gamete Cell that fuses during fertilisation, such as a sperm or egg cell

A gamete is a haploid cell that fuses with another haploid cell during fertilization in organisms that sexually reproduce and possess only one set of dissimilar chromosomes. 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 female is any individual that produces the larger type of gamete—called an ovum— and a male produces the smaller tadpole-like type—called a sperm. Sperm cells or spermatozoon 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 or a sperm. 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 diploid organism. Gametes carry half the genetic information of an individual, one ploidy of each type, and are created through meiosis, in which a germ cell undergoes two fissions, resulting in the production of four gametes. In biology, the type of gamete one produces determines the classification of their sex.

Reproduction Biological process by which new organisms are generated from one or more parent organisms

Reproduction is the biological process by which new individual organisms – "offspring" – are produced from their "parents". Reproduction is a fundamental feature of all known life; each individual organism exists as the result of reproduction. There are two forms of reproduction: asexual and sexual.

Sex Specialization of organisms into male or female varieties

Organisms of many species are specialized into male and female varieties, each known as a sex. Sexual reproduction involves the combining and mixing of genetic traits: specialized cells known as gametes combine to form offspring that inherit traits from each parent. The gametes produced by an organism define its sex: males produce small gametes while females produce large gametes. Individual organisms which produce both male and female gametes are termed hermaphroditic. Gametes can be identical in form and function, but, in many cases, an asymmetry has evolved such that two different types of gametes (heterogametes) exist.

Sex organ Body part involved in sexual reproduction

A sex organ is any part of an animal's body that is involved in sexual reproduction. The reproductive organs together constitute the reproductive system. The testis in the male, and the ovary in the female, are called the primary sex organs. All others are called secondary sex organs, divided between the external sex organs—the genitals or genitalia, visible at birth in both sexes—and the internal sex organs.

Fertilisation Union of gametes of opposite sexes during the process of sexual reproduction to form a zygote

Fertilisation or fertilization, also known as generative fertilisation, syngamy and impregnation, is the fusion of gametes to give rise to a new individual organism or offspring and initiate its development. Processes such as insemination or pollination which happen before the fusion of gametes are also sometimes informally called fertilization. The cycle of fertilisation and development of new individuals is called sexual reproduction. During double fertilisation in angiosperms the haploid male gamete combines with two haploid polar nuclei to form a triploid primary endosperm nucleus by the process of vegetative fertilisation.

XY sex-determination system

The XY sex-determination system is a sex-determination system used to classify many mammals, including humans, some insects (Drosophila), some snakes, some fish (guppies), and some plants. In this system, the sex of an individual is determined by a pair of sex chromosomes. Females typically have two of the same kind of sex chromosome (XX), and are called the homogametic sex. Males typically have two different kinds of sex chromosomes (XY), and are called the heterogametic sex.

Gonad

A gonad,sex gland, or reproductive gland is a mixed gland that produces the gametes and sex hormones of an organism. In the female of the species the reproductive cells are the egg cells, and in the male the reproductive cells are the sperm. The male gonad, the testicle, produces sperm in the form of spermatozoa. The female gonad, the ovary, produces egg cells. Both of these gametes are haploid cells.

Egg cell Female reproductive cell in most anisogamous organisms

The egg cell, or ovum, is the female reproductive cell, or gamete, in most anisogamous organisms. The term is used when the female gamete is not capable of movement (non-motile). If the male gamete (sperm) is capable of movement, the type of sexual reproduction is also classified as oogamous.

Anisogamy Sexual reproduction involving a large, "female" gamete and a small, "male" gamete

Anisogamy is the form of sexual reproduction that involves the union or fusion of two gametes, which differ in size and/or form. The smaller gamete is considered to be male, whereas the larger gamete is regarded as female.

Reproductive biology includes both sexual and asexual reproduction.

Male The sex of an organism which produces sperm

A male (♂) organism is the physiological sex that produces the gamete known as sperm. A male gamete can fuse with a larger female gamete, or ovum, in the process of fertilization. A male cannot reproduce sexually without access to at least one ovum from a female, but some organisms can reproduce both sexually and asexually. Most male mammals, including male humans, have a Y chromosome, which codes for the production of larger amounts of testosterone to develop male reproductive organs. Not all species share a common sex-determination system. In most animals, including humans, sex is determined genetically; however, species such as Cymothoa exigua change sex depending on the number of females present in the vicinity. Male can also be used to refer to gender.

Human reproductive system

The human reproductive system includes the male reproductive system which functions to produce and deposit sperm; and the female reproductive system which functions to produce egg cells, and to protect and nourish the fetus until birth. Humans have a high level of sexual differentiation. In addition to differences in nearly every reproductive organ, there are numerous differences in typical secondary sex characteristics.

Oogamy Sexual reproduction involving a large, non-motile female gamete and a small, motile male gamete

Oogamy is the familiar form of sexual reproduction. It is a form of anisogamy (heterogamy) in which the female gamete is significantly larger than the male gamete and is non-motile. The male gametes are typically highly motile and are usually tasked with all of the travel necessary to bring the respective gametes together. The prevalence of oogamy in higher animals leads to the conclusion that this specialization of the gametes results in their performing their respective tasks better and more efficiently than those tasks could be performed by generalist isogametes, particularly the ability to concentrate high-energy substances in a smaller number of ova.

Human reproduction Procreative biological processes of humanity

Human reproduction is any form of sexual reproduction resulting in human fertilization. It typically involves sexual intercourse between a man and a woman. During sexual intercourse, the interaction between the male and female reproductive systems results in fertilization of the woman's ovum by the man's sperm. These are specialized reproductive cells called gametes, created in a process called meiosis. While normal cells contains 46 chromosomes, 23 pairs, gamete cells only contain 23 chromosomes, and it is when these two cells merge into one zygote cell that genetic recombination occurs and the new zygote contains 23 chromosomes from each parent, giving them 23 pairs. A typical 9-month gestation period is followed by childbirth. The fertilization of the ovum may be achieved by artificial insemination methods, which do not involve sexual intercourse. Assisted reproductive technology also exists.

Plant reproduction is the production of new offspring in plants, which can be accomplished by sexual or asexual reproduction. Sexual reproduction produces offspring by the fusion of gametes, resulting in offspring genetically different from the parent or parents. Asexual reproduction produces new individuals without the fusion of gametes, genetically identical to the parent plants and each other, except when mutations occur.

Man Male adult human

A man is an adult male human. Prior to adulthood, a male human is referred to as a boy.

The reproductive system of an organism, also known as the genital system, is the biological system made up of all the anatomical organs involved in sexual reproduction. Many non-living substances such as fluids, hormones, and pheromones are also important accessories to the reproductive system. Unlike most organ systems, the sexes of differentiated species often have significant differences. These differences allow for a combination of genetic material between two individuals, which allows for the possibility of greater genetic fitness of the offspring.

Sexual reproduction Reproduction process that creates a new organism by combining the genetic material of two organisms

Sexual reproduction is a type of reproduction that involves a complex life cycle in which a gamete with a single set of chromosomes (haploid) combines with another to produce an organism composed of cells with two sets of chromosomes (diploid). Sexual reproduction is the most common life cycle in multicellular eukaryotes, such as animals, fungi and plants. Sexual reproduction does not occur in prokaryotes, but they have processes with similar effects such as bacterial conjugation, transformation and transduction, which may have been precursors to sexual reproduction in early eukaryotes.

Mammalian reproduction Most mammals are viviparous, giving birth to live young

Most mammals are viviparous, giving birth to live young. However, the five species of monotreme, the platypuses and the echidnas, lay eggs. The monotremes have a sex determination system different from that of most other mammals. In particular, the sex chromosomes of a platypus are more like those of a chicken than those of a therian mammal.

References

  1. 1 2 Martin, Elizabeth; Hine, Robert (2015). A Dictionary of Biology. Oxford University Press. p. 222. ISBN   978-0-19-871437-8. Female 1. Denoting the gamete (sex cell) that, during sexual reproduction, fuses with a male gamete in the process of fertilization. Female gametes are generally larger than the male gametes and are usually immotile (see Oosphere; Ovum). 2. (Denoting) an individual organism whose reproductive organs produce only female gametes.
  2. Grzimek, Bernhard (2003). Grzimek's Animal Life Encyclopedia. 1. Gale. pp. 16–17. ISBN   978-0-7876-5362-0. During sexual reproduction, each parent animal must form specialized cells known as gametes...In virtually all animals that reproduce sexually, the gametes occur in two morphologically distinct forms corresponding to male and female. These distinctions in form and structure are related to the specific functions of each gamete. The differences become apparent during the latter stages of spermatogenesis (for male gametes) and oogenesis (for female gametes)....After oogenetic meiosis, the morphological transformation of the female gamete generally includes development of a large oocyte that does not move around....The ambiguous term "egg" is often applied to oocytes and other fertilizable stages of female gametes....Spermatogenesis and oogenesis most often occur in different individual animals known as males and females respectively.
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