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In this diagram of a duplicated chromosome, (2) identifies the centromere—the region that joins the two sister chromatids, or each half of the chromosome. In prophase of mitosis, specialized regions on centromeres called kinetochores attach chromosomes to spindle fibers. The centromere links a pair of sister chromatids together during cell ...
an inner kinetochore, which is tightly associated with the centromere DNA and assembled in a specialized form of chromatin that persists throughout the cell cycle; an outer kinetochore, which interacts with microtubules ; the outer kinetochore is a very dynamic structure with many identical components, which are assembled and functional only ...
Chromosome 15 is one of the 23 pairs of chromosomes in humans.People normally have two copies of this chromosome. Chromosome 15 spans about 99.7 million base pairs (the building material of DNA) and represents between 3% and 3.5% of the total DNA in cells.
The centrosome is thought to have evolved only in the metazoan lineage of eukaryotic cells. [2] Fungi and plants lack centrosomes and therefore use other structures to organize their microtubules. [3] [4] Although the centrosome has a key role in efficient mitosis in animal cells, it is not essential in certain fly and flatworm species. [5] [6] [7]
In addition to the centromere, one or more secondary constrictions can be observed in some chromosomes at metaphase. In humans they are usually associated with the short arm of an acrocentric chromosome, [1] such as in the chromosomes 13, 14, 15, 21, & 22.
ATM is a key kinase in the DNA damage checkpoint. Defects in cohesion can increase genome instability , [ 19 ] a result consistent with the ties between cohesion and DNA damage pathways. In the bacterium Escherichia coli , repair of mitomycin C -induced DNA damages occurs by a sister chromatid cohesion process involving the RecN protein. [ 20 ]
Three types of cell division: binary fission (taking place in prokaryotes), mitosis and meiosis (taking place in eukaryotes).. When cells are ready to divide, because cell size is big enough or because they receive the appropriate stimulus, [20] they activate the mechanism to enter into the cell cycle, and they duplicate most organelles during S (synthesis) phase, including their centrosome.
The microtubule-organizing center (MTOC) is a structure found in eukaryotic cells from which microtubules emerge. MTOCs have two main functions: the organization of eukaryotic flagella and cilia and the organization of the mitotic and meiotic spindle apparatus, which separate the chromosomes during cell division.