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The cell cycle in eukaryotes: I = Interphase, M = Mitosis, G 0 = Gap 0, G 1 = Gap 1, G 2 = Gap 2, S = Synthesis, G 3 = Gap 3. Cell division is the process by which a parent cell divides into two daughter cells. [1] Cell division usually occurs as part of a larger cell cycle in which the cell grows and replicates its chromosome(s) before dividing.
This is an accepted version of this page This is the latest accepted revision, reviewed on 29 January 2025. Process in which chromosomes are replicated and separated into two new identical nuclei For the type of cell division in sexually reproducing organisms used to produce gametes, see Meiosis. For excessive constriction of the pupils, see Miosis. For the parasitic infestation, see Myiasis ...
In embryology, cleavage is the division of cells in the early development of the embryo, following fertilization. [1] The zygotes of many species undergo rapid cell cycles with no significant overall growth, producing a cluster of cells the same size as the original zygote.
The first evidence of multicellularity is from cyanobacteria-like organisms that lived between 3 and 3.5 billion years ago. [22] Other early fossils of multicellular organisms include the contested Grypania spiralis and the fossils of the black shales of the Palaeoproterozoic Francevillian Group Fossil B Formation in Gabon .
In botany, the term lusus was used. [1] In horticulture, the spelling clon was used until the early twentieth century; the final e came into use to indicate the vowel is a "long o" instead of a "short o". [2] [3] Since the term entered the popular lexicon in a more general context, the spelling clone has been used exclusively.
The egg cell is generally asymmetric, having an animal pole (future ectoderm).It is covered with protective envelopes, with different layers. The first envelope – the one in contact with the membrane of the egg – is made of glycoproteins and is known as the vitelline membrane (zona pellucida in mammals).