Female
Encyclopedia
Gender
Gender is a range of characteristics used to distinguish between males and females, particularly in the cases of men and women and the masculine and feminine attributes assigned to them. Depending on the context, the discriminating characteristics vary from sex to social role to gender identity...
of an organism
Organism
In biology, an organism is any contiguous living system . In at least some form, all organisms are capable of response to stimuli, reproduction, growth and development, and maintenance of homoeostasis as a stable whole.An organism may either be unicellular or, as in the case of humans, comprise...
, or a part of an organism, which produces non-mobile ova
Ovum
An ovum is a haploid female reproductive cell or gamete. Both animals and embryophytes have ova. The term ovule is used for the young ovum of an animal, as well as the plant structure that carries the female gametophyte and egg cell and develops into a seed after fertilization...
(egg cells).
Defining characteristics
The ovaOvum
An ovum is a haploid female reproductive cell or gamete. Both animals and embryophytes have ova. The term ovule is used for the young ovum of an animal, as well as the plant structure that carries the female gametophyte and egg cell and develops into a seed after fertilization...
are defined as the larger gamete
Gamete
A gamete is a cell that fuses with another cell during fertilization in organisms that reproduce sexually...
s in a heterogamous reproduction system, while the smaller, usually motile gamete, the spermatozoon
Spermatozoon
A spermatozoon is a motile sperm cell, or moving form of the haploid cell that is the male gamete. A spermatozoon joins an ovum to form a zygote...
, is produced by the male
Male
Male refers to the biological sex of an organism, or part of an organism, which produces small mobile gametes, called spermatozoa. Each spermatozoon can fuse with a larger female gamete or ovum, in the process of fertilization...
. A female individual cannot reproduce sexually
Sexual reproduction
Sexual reproduction is the creation of a new organism by combining the genetic material of two organisms. There are two main processes during sexual reproduction; they are: meiosis, involving the halving of the number of chromosomes; and fertilization, involving the fusion of two gametes and the...
without access to the gametes of a male
Male
Male refers to the biological sex of an organism, or part of an organism, which produces small mobile gametes, called spermatozoa. Each spermatozoon can fuse with a larger female gamete or ovum, in the process of fertilization...
(an exception is parthenogenesis
Parthenogenesis
Parthenogenesis is a form of asexual reproduction found in females, where growth and development of embryos occur without fertilization by a male...
). Some organisms can reproduce both sexually
Sexual reproduction
Sexual reproduction is the creation of a new organism by combining the genetic material of two organisms. There are two main processes during sexual reproduction; they are: meiosis, involving the halving of the number of chromosomes; and fertilization, involving the fusion of two gametes and the...
and asexually
Asexual reproduction
Asexual reproduction is a mode of reproduction by which offspring arise from a single parent, and inherit the genes of that parent only, it is reproduction which does not involve meiosis, ploidy reduction, or fertilization. A more stringent definition is agamogenesis which is reproduction without...
.
There is no single genetic
Genetics
Genetics , a discipline of biology, is the science of genes, heredity, and variation in living organisms....
mechanism behind sex differences in different species and the existence of two sexes seems to have evolved
Evolution
Evolution is any change across successive generations in the heritable characteristics of biological populations. Evolutionary processes give rise to diversity at every level of biological organisation, including species, individual organisms and molecules such as DNA and proteins.Life on Earth...
multiple times independently in different evolutionary lineages
Lineage (evolution)
An evolutionary lineage is a sequence of species, that form a line of descent, each new species the direct result of speciation from an immediate ancestral species. Lineages are subsets of the evolutionary tree of life. Lineages are often determined by the techniques of molecular systematics.-...
. Patterns of sexual reproduction include
- isogamousIsogamyIsogamy is a form of sexual reproduction that involves gametes of similar morphology , differing only in allele expression in one or more mating-type regions...
species with two or more mating typeMating typeMating types occur in eukaryotes that undergo sexual reproduction via isogamy. Since the gametes of different mating types look alike, they are often referred to by numbers, letters, or simply "+" and "-" instead of "male" and "female." Mating can only take place between different mating...
s with gametes of identical form and behavior (but different at the molecular level), - anisogamousAnisogamyAnisogamy refers to a form of sexual reproduction involving the union or fusion of two dissimilar gametes — anisogamous, anisogamic,...
species with gameteGameteA gamete is a cell that fuses with another cell during fertilization in organisms that reproduce sexually...
s of male and female types, - oogamousOogamyOogamy is the familiar form of sexual reproduction. It is a form of anisogamy in which the female gamete is significantly larger than the male gamete and is non-motile. The male gametes are typically highly motile spermatozoa competing for the fertilization of the immotile egg.By contrast to...
species in which the female gamete is very much larger than the male and has no ability to move. There is an argument that this pattern was driven by the physical constraints on the mechanisms by which two gametes get together as required for sexual reproductionSexual reproductionSexual reproduction is the creation of a new organism by combining the genetic material of two organisms. There are two main processes during sexual reproduction; they are: meiosis, involving the halving of the number of chromosomes; and fertilization, involving the fusion of two gametes and the...
.
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 animal
Animal
Animals are a major group of multicellular, eukaryotic organisms of the kingdom Animalia or Metazoa. Their body plan eventually becomes fixed as they develop, although some undergo a process of metamorphosis later on in their life. Most animals are motile, meaning they can move spontaneously and...
s; egg cells are produced by chytrids, diatom
Diatom
Diatoms are a major group of algae, and are one of the most common types of phytoplankton. Most diatoms are unicellular, although they can exist as colonies in the shape of filaments or ribbons , fans , zigzags , or stellate colonies . Diatoms are producers within the food chain...
s, water mould
Water mould
Oömycota or oömycetes form a distinct phylogenetic lineage of fungus-like eukaryotic microorganisms . They are filamentous, microscopic, absorptive organisms that reproduce both sexually and asexually...
s and land plants
Plant
Plants are living organisms belonging to the kingdom Plantae. Precise definitions of the kingdom vary, but as the term is used here, plants include familiar organisms such as trees, flowers, herbs, bushes, grasses, vines, ferns, mosses, and green algae. The group is also called green plants or...
, 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 sporophyte
Sporophyte
All land plants, and some algae, have life cycles in which a haploid gametophyte generation alternates with a diploid sporophyte, the generation of a plant or algae that has a double set of chromosomes. A multicellular sporophyte generation or phase is present in the life cycle of all land plants...
s that give rise to male and female plants.
Etymology and usage
The word female comes from the Latin femella, the diminutive form of femina, meaning "womanWoman
A woman , pl: women is a female human. The term woman is usually reserved for an adult, with the term girl being the usual term for a female child or adolescent...
," which is not etymologically related to the word male. In the late 14th century, the spelling was altered in English to parallel the spelling of male.
Mammalian female
A distinguishing characteristic of the classClass (biology)
In biological classification, class is* a taxonomic rank. Other well-known ranks are life, domain, kingdom, phylum, order, family, genus, and species, with class fitting between phylum and order...
Mammalia is the presence of mammary gland
Mammary gland
A mammary gland is an organ in mammals that produces milk to feed young offspring. Mammals get their name from the word "mammary". In ruminants such as cows, goats, and deer, the mammary glands are contained in their udders...
s. The mammary glands are modified sweat glands that produce milk
Milk
Milk is a white liquid produced by the mammary glands of mammals. It is the primary source of nutrition for young mammals before they are able to digest other types of food. Early-lactation milk contains colostrum, which carries the mother's antibodies to the baby and can reduce the risk of many...
, which is used to feed the young for some time after birth. Only mammals produce milk
Lactation
Lactation describes the secretion of milk from the mammary glands and the period of time that a mother lactates to feed her young. The process occurs in all female mammals, however it predates mammals. In humans the process of feeding milk is called breastfeeding or nursing...
. Mammary glands are most obvious in humans, as the female human body stores large amounts of fatty tissue near the nipples, resulting in prominent breast
Breast
The breast is the upper ventral region of the torso of a primate, in left and right sides, which in a female contains the mammary gland that secretes milk used to feed infants.Both men and women develop breasts from the same embryological tissues...
s. Today some human females also surgically augment their breast size. However, mammary glands are present in all mammals, although they are vestigial in the male of the species.
The mammalian female has two copies of the X chromosome
X chromosome
The X chromosome is one of the two sex-determining chromosomes in many animal species, including mammals and is common in both males and females. It is a part of the XY sex-determination system and X0 sex-determination system...
as opposed to the male which carries only one X and one smaller Y chromosome
Y chromosome
The Y chromosome is one of the two sex-determining chromosomes in most mammals, including humans. In mammals, it contains the gene SRY, which triggers testis development if present. The human Y chromosome is composed of about 60 million base pairs...
. To compensate for the difference in size, one of the female's X chromosomes is randomly inactivated
X-inactivation
X-inactivation is a process by which one of the two copies of the X chromosome present in female mammals is inactivated. The inactive X chromosome is silenced by packaging into transcriptionally inactive heterochromatin...
in each cell. In birds and reptiles, by contrast, it is the female who is heterozygous and carries a Z and a W chromosome whilst the male carries two Z chromosomes.
Mammalian females bear live young (with the rare exception of monotremes, which lay eggs). Some non-mammalian species, such as guppies
Guppy
The guppy , also known as the millionfish, is one of the most popular freshwater aquarium fish species in the world. It is a small member of the Poeciliidae family [females long, males long] and like all other members of the family, is live-bearing....
, have analogous reproductive structures; and some other non-mammals, such as shark
Shark
Sharks are a type of fish with a full cartilaginous skeleton and a highly streamlined body. The earliest known sharks date from more than 420 million years ago....
s, whose eggs hatch inside their bodies, also have the appearance of bearing live young.
Symbol
A common symbol used to represent the female sex is ♀ (UnicodeUnicode
Unicode is a computing industry standard for the consistent encoding, representation and handling of text expressed in most of the world's writing systems...
: U+2640 Alt codes
Alt codes
On personal computers running the Microsoft Windows or DOS operating systems, additional characters to those available in the current keyboard layout can be typed using an Alt code: pressing and holding the Alt key while entering a character code with the keyboard's numeric keypad...
: Alt+12), a circle with a small cross underneath. According to Schott, the most established view is that the male and female symbols "are derived from contractions in Greek script of the Greek names of these planets, namely Thouros (Mars) and Phosphoros (Venus). These derivations have been traced by Renkama who illustrated how Greek letters can be transformed into the graphic male and female symbols still recognised today." Thouros was abbreviated by θρ, and Phosphoros by Φκ, which were contracted into the modern symbols.
Sex determination
The sexSex
In biology, sex is a process of combining and mixing genetic traits, often resulting in the specialization of organisms into a male or female variety . Sexual reproduction involves combining specialized cells to form offspring that inherit traits from both parents...
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 with male and female sexes have individuals that are either male or female, hermaphroditic
Hermaphrodite
In biology, a hermaphrodite is an organism that has reproductive organs normally associated with both male and female sexes.Many taxonomic groups of animals do not have separate sexes. In these groups, hermaphroditism is a normal condition, enabling a form of sexual reproduction in which both...
animals have both male and female reproductive organs.
Genetic determination
The gender of most mammalMammal
Mammals are members of a class of air-breathing vertebrate animals characterised by the possession of endothermy, hair, three middle ear bones, and mammary glands functional in mothers with young...
s, including human
Human
Humans are the only living species in the Homo genus...
s, is genetically determined by the XY sex-determination system
XY sex-determination system
The XY sex-determination system is the sex-determination system found in humans, most other mammals, some insects and some plants . In this system, females have two of the same kind of sex chromosome , and are called the homogametic sex. Males have two distinct sex chromosomes , and are called...
where males have X and Y (as opposed to X and X) sex chromosome
Chromosome
A chromosome is an organized structure of DNA and protein found in cells. It is a single piece of coiled DNA containing many genes, regulatory elements and other nucleotide sequences. Chromosomes also contain DNA-bound proteins, which serve to package the DNA and control its functions.Chromosomes...
s. 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 boy
Boy
A boy is a young male human , as contrasted to its female counterpart, girl, or an adult male, a man.The term "boy" is primarily used to indicate biological sex distinctions, cultural gender role distinctions or both...
, while an X sperm and an X egg produce a girl
Girl
A girl is any female human from birth through childhood and adolescence to attainment of adulthood. The term may also be used to mean a young woman.-Etymology:...
. The ZW sex-determination system
ZW sex-determination system
The ZW sex-determination system is a system that determines the sex of offspring in birds, some fish and crustaceans such as the giant river prawn, some insects , and some reptiles, including Komodo dragons...
, where males have ZZ (as opposed to ZW) sex chromosomes, is found in bird
Bird
Birds are feathered, winged, bipedal, endothermic , egg-laying, vertebrate animals. Around 10,000 living species and 188 families makes them the most speciose class of tetrapod vertebrates. They inhabit ecosystems across the globe, from the Arctic to the Antarctic. Extant birds range in size from...
s and some insect
Insect
Insects are a class of living creatures within the arthropods that have a chitinous exoskeleton, a three-part body , three pairs of jointed legs, compound eyes, and two antennae...
s and other organisms. Members of Hymenoptera
Hymenoptera
Hymenoptera is one of the largest orders of insects, comprising the sawflies, wasps, bees and ants. There are over 130,000 recognized species, with many more remaining to be described. The name refers to the heavy wings of the insects, and is derived from the Ancient Greek ὑμήν : membrane and...
, such as ant
Ant
Ants are social insects of the family Formicidae and, along with the related wasps and bees, belong to the order Hymenoptera. Ants evolved from wasp-like ancestors in the mid-Cretaceous period between 110 and 130 million years ago and diversified after the rise of flowering plants. More than...
s and bee
Bee
Bees are flying insects closely related to wasps and ants, and are known for their role in pollination and for producing honey and beeswax. Bees are a monophyletic lineage within the superfamily Apoidea, presently classified by the unranked taxon name Anthophila...
s, are determined by haplodiploidy, where most males are haploid and females and some sterile males are diploid.
Environmental determination
The young of some species develop into one sex or the other depending on local environmental conditions, e.g. many crocodilians' gender is influenced by the temperature of their eggs. Other species (such as the gobyGoby
The gobies form the family Gobiidae, which is one of the largest families of fish, with more than 2,000 species in more than 200 genera. Most are relatively small, typically less than 10 cm in length...
) can transform, as adults, from one sex to the other in response to local reproductive conditions (such as a shortage of males).
See also
- DakiniDakiniA dakini is a tantric deity described as a female embodiment of enlightened energy. In the Tibetan language, dakini is rendered khandroma which means 'she who traverses the sky' or 'she who moves in space'. Sometimes the term is translated poetically as 'sky dancer' or 'sky walker'. The dakini, in...
- FemininityFemininityFemininity is a set of attributes, behaviors, and roles generally associated with girls and women. Though socially constructed, femininity is made up of both socially defined and biologically created factors...
- Feminine side
- GestationGestationGestation is the carrying of an embryo or fetus inside a female viviparous animal. Mammals during pregnancy can have one or more gestations at the same time ....
- GirlGirlA girl is any female human from birth through childhood and adolescence to attainment of adulthood. The term may also be used to mean a young woman.-Etymology:...
- LactationLactationLactation describes the secretion of milk from the mammary glands and the period of time that a mother lactates to feed her young. The process occurs in all female mammals, however it predates mammals. In humans the process of feeding milk is called breastfeeding or nursing...
- MaleMaleMale refers to the biological sex of an organism, or part of an organism, which produces small mobile gametes, called spermatozoa. Each spermatozoon can fuse with a larger female gamete or ovum, in the process of fertilization...
- Transwoman
- Transman
- WomanWomanA woman , pl: women is a female human. The term woman is usually reserved for an adult, with the term girl being the usual term for a female child or adolescent...
- WomynWomyn"Womyn" is one of a number of alternative spellings of the word "women" used by some feminist writers. There are many alternative spellings, including "wimmin", "womban", "wom!n"...