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Metaphase (from Ancient Greek μετα- beyond, above, transcending and from Ancient Greek φάσις (phásis) 'appearance') is a stage of mitosis in the eukaryotic cell cycle in which chromosomes are at their second-most condensed and coiled stage (they are at their most condensed in anaphase). [1]
The eukaryotic cell cycle consists of four distinct phases: G 1 phase, S phase (synthesis), G 2 phase (collectively known as interphase) and M phase (mitosis and cytokinesis). M phase is itself composed of two tightly coupled processes: mitosis, in which the cell's nucleus divides, and cytokinesis, in which the cell's cytoplasm and cell membrane divides forming two daughter cells.
Curiously, G 2 phase is not a necessary part of the cell cycle, as some cell types (particularly young Xenopus embryos [1] and some cancers [2]) proceed directly from DNA replication to mitosis. Though much is known about the genetic network which regulates G2 phase and subsequent entry into mitosis, there is still much to be discovered ...
This is an accepted version of this page This is the latest accepted revision, reviewed on 22 February 2025. DNA molecule containing genetic material of a cell This article is about the DNA molecule. For the genetic algorithm, see Chromosome (genetic algorithm). Chromosome (10 7 - 10 10 bp) DNA Gene (10 3 - 10 6 bp) Function A chromosome and its packaged long strand of DNA unraveled. The DNA's ...
The spindle checkpoint, also known as the metaphase-to-anaphase transition, the spindle assembly checkpoint (SAC), the metaphase checkpoint, or the mitotic checkpoint, is a cell cycle checkpoint during metaphase of mitosis or meiosis that prevents the separation of the duplicated chromosomes until each chromosome is properly attached to the ...
Schematic karyogram of the human chromosomes, showing their usual state in the G 0 and G 1 phase of the cell cycle. At top center it also shows the chromosome 3 pair in metaphase (annotated as "Meta."), which takes place after having undergone DNA synthesis which occurs in the S phase (annotated as S) of the cell cycle.
The basic number of chromosomes in the somatic cells of an individual or a species is called the somatic number and is designated 2n. In the germ-line (the sex cells) the chromosome number is n (humans: n = 23). [4] [5] p28 Thus, in humans 2n = 46. So, in normal diploid organisms, autosomal chromosomes are present in two copies.
In most eukaryotes, a cell carries two versions of each gene, each referred to as an allele. Each parent passes on one allele to each offspring. An individual gamete inherits a complete haploid complement of alleles on chromosomes that are independently selected from each pair of chromatids lined up on the metaphase plate. Without recombination ...