Sexual reproduction is the production of offspring by the fusion of specialized male and feminine cells called gametes. Gametes are haploid and fuse to make the embryo or zygote, which eventually develops into a replacement organism. In comparison to agamogenesis, it's a slow process. This helps us to define gamete.
This will help us to understand what is the meaning of gametes and explain gametes. The process of formation of gametes is understood as gametogenesis. Two types of gametes are male gametes and feminine gametes. they're haploid in nature. Gametes example animals are the male gametes, called sperms that are produced within the testes whereas the feminine gametes or the eggs develop within the ovaries. as compared to male gametes, female gametes are produced in much smaller numbers.
Gametes definition biology is that most of the animals have a diploid body hence they form gametes by meiotic division. a couple of animal species example ants, wasps show an unusual sort of sex differentiation. The males are haploid and make haploid sperms by mitosis. The females are diploid and make haploid eggs by meiosis. If an egg is fertilized, it develops into a female while unfertilized eggs become males. Meiosis is an important feature of the sexual cycle. It leads to the formation of daughter cells, each with half the amount of chromosomes of the parent cell. During fertilization, the nuclei of two gamete cells fuse and therefore the zygote thus features a fixed number of chromosomes for every species. altogether organisms, this number of chromosomes represents the diploid condition. If meiosis doesn't occur, a fusion of gametes would end in the doubling of the chromosomes for every successive sexually reproduced generation. This example is prevented by a discount within the diploid number of chromosomes to the haploid number during gametogenesis. This gives us a basic understanding of what are gametes or what is gamete definition biology.
Transfer of Gametes
The gamete definition above gave us a rough idea about the meaning of what are gametes. After the formation of gametes, it's essential that male and feminine gametes are brought together in physical contact. the planet is filled with a spread of organisms and usually, their males and females go their own way. But to breed they need to urge together within the right pairs, one male and one female of an equivalent species and of the proper age. The foremost primitive mechanisms for proper gametes to return together are chemical. during a majority of organisms, the male gametes are motile and therefore the female gametes are stationary. Exceptions are a couple of fungi and algae during which both sorts of gametes are motile and that they differ only in certain surface proteins. they're usually released in water and move towards one another chemotactically. They, however, cannot recognize one another until they touch. In another group of plants( bryophytes and pteridophytes), the male gamete is motile and therefore the female gamete is stationery. Although just one male gamete is required to fertilize the egg. they're produced during a very sizable amount to make sure fertilization.
In seed plants, male gametes develop within the pollen and feminine gamete or egg lies within the embryo sac within the ovule. To bring male and feminine gametes together, it's necessary that pollens from anther are transferred to the stigma. This process is understood as pollination. If the transfer occurs between two plants of various genetic makeup, the method is understood as cross-pollination. If the transfer takes place between flowers of the identical genotype, the method is understood as self-pollination. It's common to consider self-pollination occurring within one flower on a plant-like garden pea where petals enclose the stamens in such a way that the pollen features a little chance of escaping. However, self-pollination also occurs if pollen is transferred between different flowers on an equivalent plant. It's helped by insects moving from flower to flower collecting nectar. Pollens also are transferred between flowers on two different plants which are genetically identical. This is often called cross-pollination.
In dioecious animals, male and feminine gametes are formed in several individuals. For fertilization to occur, sperm and egg must get together. Animals have evolved different strategies for this. For instance, many animals secrete sex pheromones to draw in their partners. Male and feminine insects just like the silkworm moth produce tiny amounts of very volatile pheromones that diffuse very long distances. Only male moths of this species are attracted towards female moths by distinctive alcohol produced by the feminine.
Several marine invertebrates release their gametes into the water, thus there's no need for the parent to form direct contact. In others, mating is vital to bring male and feminine gametes in close contact. This whole paragraph helps us to understand the gamete definition biology.
Here, we will define gamete organs that are responsible for the formation of gametes. The primary sex organs which are testes in male and ovaries within the female are liable for the formation of gametes. This process is understood as gametogenesis.
In testis, the immature male germ cells, spermatogonia produce sperms by process of spermatogenesis that begins at puberty. It occurs in four stages:
Spermatocytogenesis: The spermatogonia present on the wall of the seminiferous tubules multiply by mitotic division and increase in numbers. Each spermatogonia is diploid containing 46 chromosomes.
Meiosis-I: A primary spermatocyte is diploid with 44+ XY chromosomes. It completes the primary meiotic division resulting in the formation of two equal, haploid cells called secondary spermatocytes which have 23 chromosomes.
Meiosis-II: The secondary spermatocytes undergo the second meiotic division to supply four equal spermatids. The amount of chromosomes in each spermatid is 23.
Spermiogenesis: The transformation of spermatids into sperms is understood as spermiogenesis. From one primary spermatocyte, four haploid sperms are formed.
We can conclude that gametes are responsible for transferring information in the form of genetic material from one generation to another. They are haploid in nature and are formed by reductional division. This division is also known as meiosis.