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Gametogenesis is a biological process by which diploid or haploid precursor cells undergo cell division and differentiation to form mature haploid gametes.Depending on the biological life cycle of the organism, gametogenesis occurs by meiotic division of diploid gametocytes into various gametes, or by mitosis.
Speciation via polyploidy: A diploid cell undergoes failed meiosis, producing diploid gametes, which self-fertilize to produce a tetraploid zygote. Polyploidy is frequent in plants, some estimates suggesting that 30–80% of living plant species are polyploid, and many lineages show evidence of ancient polyploidy ( paleopolyploidy ) in their ...
Animals have life cycles with a single diploid multicellular phase that produces haploid gametes directly by meiosis. Male gametes are called sperm, and female gametes are called eggs or ova. In animals, fertilization of the ovum by a sperm results in the formation of a diploid zygote that develops by repeated mitotic divisions into a diploid ...
Alternation of generations is defined as the alternation of multicellular diploid and haploid forms in the organism's life cycle, regardless of whether these forms are free-living. [6] In some species, such as the alga Ulva lactuca , the diploid and haploid forms are indeed both free-living independent organisms, essentially identical in ...
Gametes are an organism's reproductive cells, also referred to as sex cells. [2] The name gamete was introduced by the German cytologist Eduard Strasburger in 1878. [3] Gametes of both mating individuals can be the same size and shape, a condition known as isogamy.
The diploid zygote undergoes repeated cellular division by mitosis to grow into the organism. In the haplontic life cycle (with post-zygotic meiosis), the organism is haploid, by the proliferation and differentiation of a single haploid cell called the gamete. Two organisms of opposing sex contribute their haploid gametes to form a diploid zygote.
Fertilization is the fusion of gametes to produce a new organism. In animals, the process involves a sperm fusing with an ovum , which eventually leads to the development of an embryo . Depending on the animal species, the process can occur within the body of the female in internal fertilization, or outside in the case of external fertilization.
These gametes are produced by meiosis, which halves the number of chromosomes in the diploid germ cells. 6) The short-lived diploid state of haploid organisms, a zygote generated by the union of two haploid gametes during sex. 7) The diploid zygote which has just been fertilized by the union of haploid egg and sperm during sex.