Upper arm muscle strain: Introduction. Upper arm muscle strain: Damage to the upper arm muscle due to over-stretching of the muscle tissue. The damage involves tearing the muscle tissue. Small blood vessels may also be damaged which can cause bruising. The symptoms may vary from mild to severe depending on the severity of the damage.
In prophase of mitosis, specialized regions on centromeres called kinetochores attach chromosomes to spindle fibers. The centromere (centro- + -mere) is the part of a chromosome that links sister chromatids. During mitosis, spindle fibers attach to the centromere via the kinetochore.Centromeres were first defined as genetic loci that direhromosomes.hese are X-shaped chromosomes, with the centromere in the middle so that the two arms of the chromosomes are almost equal. A chromosome is metacentric if its two arms are roughly equal in length. In a normal human karyotype, two chromosomes are considered metacentric: chromosomes 1 and 3.
Compaction of the duplicated chromosomes during cell division (mitosis or meiosis) results either in a four-arm structure (pictured to the right) if the centromere is located in the middle of the chromosome or a two-arm structure if the centromere is located near one of the ends. chromosome (chromo- + -some) is a packaged and organized structure containing most of the DNA of a living organism.