Everything about Gamete totally explained
A
gamete (from
Ancient Greek γαμετης; translated
gamete = wife,
gametes = husband) is a cell that fuses with another gamete during
fertilization (conception) in
organisms that
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
Austrian 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) where as 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.
Gametogenesis
The production of gametes is termed
gametogenesis, during which phase
gametocytes divide by
meiosis into gametes. Meiosis reduces the number of sets of chromosomes from two to one (for example, produces haploid gametes from diploid gametocytes). Organs that produce gametes are called
gonads in animals, and
archegonia or
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 complete set of
chromosomes (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
nuclei. After multiple
cell divisions and
cellular differentiation, a zygote
develops, first into an
embryo, and ultimately into a mature individual capable of producing gametes.
Dissimilarity
In contrast to a gamete, the diploid
somatic cells 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
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
genetic dissimilarity of
siblings.
Further Information
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