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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 ...
However, due to a lack of full centromere assemblies, base-level understanding of satellite array variation and evolution has remained weak. [5] For example, minisatellite DNA is a short region (1-5 kb) of repeating elements with length >9 nucleotides.
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.
The centromere of chromosome 6 illustrates an interesting example of centromere evolution. It was known [ further explanation needed ] that in a Catarrhini ancestor the chromosome 6 centromere was situated near position 26 Mb of the modern human chromosome.
Homochirality is an obvious characteristic of life on Earth, yet extraterrestrial samples contain largely racemic compounds. [7] It is not known whether homochirality existed before life, whether the building blocks of life must have this particular chirality, or whether life must be homochiral at all. [8] [9] What do all the unknown proteins do?
Repeated sequences (also known as repetitive elements, repeating units or repeats) are short or long patterns that occur in multiple copies throughout the genome.In many organisms, a significant fraction of the genomic DNA is repetitive, with over two-thirds of the sequence consisting of repetitive elements in humans. [1]
Anti-centromere antibodies are found in approximately 60% of patients with limited systemic scleroderma and in 15% of those with the diffuse form of scleroderma. The specificity of this test is >98%. Thus, a positive anti-centromere antibody finding is strongly suggestive of limited systemic scleroderma.
In cell biology, the centrosome (Latin centrum 'center' + Greek sōma 'body') (archaically cytocentre [1]) is an organelle that serves as the main microtubule organizing center (MTOC) of the animal cell, as well as a regulator of cell-cycle progression. The centrosome provides structure for the cell.