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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.
There are many checkpoints in the cell cycle, [1] but the three major ones are: the G1 checkpoint, also known as the Start or restriction checkpoint or Major Checkpoint; the G2/M checkpoint; and the metaphase-to-anaphase transition, also known as the spindle checkpoint. [2]
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 after having undergone DNA synthesis, occurring in the S phase (annotated as S) of the cell cycle. This interval includes the G 2 phase and metaphase (annotated as "Meta.").
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 ...
[1] [2] Karyotyping is the process by which a karyotype is discerned by determining the chromosome complement of an individual, including the number of chromosomes and any abnormalities. Micrographic karyogram of human male using Giemsa staining Schematic karyogram demonstrating the basic knowledge needed to read a karyotype
A metaphase cell positive for the BCR/ABL rearrangement using FISH. Cytogenetics is essentially a branch of genetics, but is also a part of cell biology/cytology (a subdivision of human anatomy), that is concerned with how the chromosomes relate to cell behaviour, particularly to their behaviour during mitosis and meiosis. [1]
The metaphase chromosomes are treated with trypsin (to partially digest the chromosome) and stained with Giemsa stain. Heterochromatic regions, which tend to be rich with adenine and thymine (AT-rich) DNA and relatively gene-poor, stain more darkly in G-banding.