Chapter 10 Cell Growth and Division 10 Biology Diagrams The condensation of interphase chromatin to form the compact chromosomes of mitotic cells is a key event in mitosis, critical in enabling the chromosomes to move along the mitotic spindle without becoming broken or tangled with one another. As discussed in Chapter 4, the chromatin in interphase nuclei condenses nearly a thousand fold during the formation of metaphase chromosomes.
During mitotic entry, eukaryotic chromosomes undergo condensation, a drastic compaction process that makes them manageable units for the mitotic spindle to segregate them between daughter cells ().In addition, mitotic chromosome compaction remodels genome architecture, preventing the association of many transcription and chromatin regulators to cis regulatory elements and shutting down many Mitosis is undoubtedly an extremely complex operation that needs to be conducted and controlled precisely under the penalty of dismantling genome integrity. One of the key steps in mitosis is chromosome condensation - the compaction of the chromatin into well-defined rod-shaped structures (for other recent reviews, see 1- 3). This process
Novel insights into mitotic chromosome condensation Biology Diagrams
Although chromatin condensation in mitosis is, at least in animal and plant cells, already apparent by light microscopy, assessments of the degree of compaction of mitotic chromatin in relation to its interphase state differ considerably, from two to fiftyfold as estimated by volume occupancy of an EGFP-H2B signal or by distance measurements of chromosome loci, respectively [1, 2]. When Topoisomerase IIα has been experimentally deleted prior to mitosis, the effect is a failure of chromatin condensation, and exit of the cell from mitosis without chromosome segregation having occurred. 21 In addition, it was found that "removal of TOP2A from cells arrested in prometaphase or metaphase cause dramatic loss of compacted ofthe SMC proteins fail to condense and segregate chromosomes in mitosis but remain able to perform spindle elongation cell division [30]. Anal-ysis of mitotic condensation by fluorescence microscopy
Chromosome condensation, the formation of thread-like chromosomes from interphase chromatin, is one of the most striking and earliest-described morphological changes in cells entering mitosis. As a consequence of condensation, chromatids become compacted into threads, are imparted longitudinal rigidity to withstand spindle forces, and The processes underlying the large-scale reorganisation of chromatin in mitosis that form compact mitotic chromosomes and ensure the fidelity of chromosome segregation during cell division still remain obscure. The chromosomal condensin complex is a major molecular effector of chromosome condensation and segregation in diverse organisms ranging from bacteria to humans. Condensin is a large
