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Prophase is the first stage of mitosis in animal cells, and the second stage of mitosis in plant cells. [10] At the start of prophase there are two identical copies of each chromosome in the cell due to replication in interphase. These copies are referred to as sister chromatids and are attached by DNA element called the centromere. [11]
Preprophase is an additional phase during mitosis in plant cells that does not occur in other eukaryotes such as animals or fungi. It precedes prophase and is characterized by two distinct events: The formation of the preprophase band , a dense microtubule ring underneath the plasma membrane .
Synapsis or Syzygy is the pairing of two chromosomes that occurs during meiosis. It allows matching-up of homologous pairs prior to their segregation, and possible chromosomal crossover between them. Synapsis takes place during prophase I of meiosis. When homologous chromosomes synapse, their ends are first attached to the nuclear envelope.
Chromosomal crossover, or crossing over, is the exchange of genetic material during sexual reproduction between two homologous chromosomes' non-sister chromatids that results in recombinant chromosomes. It is one of the final phases of genetic recombination, which occurs in the pachytene stage of prophase I of meiosis during a process called ...
The synaptonemal complex is a tripartite structure consisting of two parallel lateral regions and a central element. This "tripartite structure" is seen during the pachytene stage of the first meiotic prophase, both in males and in females during gametogenesis.
This is an accepted version of this page This is the latest accepted revision, reviewed on 19 December 2024. 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 ...
Zygotene (from greek "paired threads" [1]) is the second stage of prophase I during meiosis, the specialized cell division that reduces the chromosome number by half to produce haploid gametes. It follows the Leptotene stage and is followed by Pachytene stage.
The human homolog, hsSgo1, associates with centromeres during prophase and disappears when anaphase starts. [74] When Shugoshin levels are reduced by RNAi in HeLa cells, cohesin cannot remain on the centromeres during mitosis, and consequently sister chromatids separate synchronically before anaphase initiates, which triggers a long mitotic arrest.