Calcium Helps To Collapse Chromosomes

Chromatin is group of macromolecules found in cells. It is a packed up form of the long chains of DNA and RNA caused by a group of proteins called histones. This insures the DNA fits inside the cell itself; is protected from any damage that may occur; and to allow mitosis of the cell. But chromatin itself is considered to hang quite loosely inside the cell and when cells during division were observed the chromatin was found to be in the more recognisable and compact form of chromosomes; only in this state is the DNA fit to be copied and distributed to the daughter cells. So before cell division a process must occur to compact the chromatin again and this has been called chromosome condensation. The method of how this happens is still unknown and it was believed that a set of proteins called the chromosome scaffold proteins were responsible. However when these scaffolds were removed or at least severely reduced the condensation still happened albeit with some structural defects. This proves that other factors must be responsible for the condensation and so the effect dipositive metal ions has been tested to see if these have some part to play. This was suggested because it was observed that the concentration of calcium ions (Ca2+) increased by nearly five times while mitosis was taking place, a tell-tale sign that it may have a part to play. It was found that reducing the amount of Ca2+, often used for chemical messaging in cells, had an incredible impact on the process, hindering it severely. It is believed this could be due to the fact that as part of chromosomes massive chain structure there are repeating units containing negative charges. When histones bind the original DNA they remove about 60% of the negative groups. If the other 40% are never neutralised, because there is a lack of positive ions, then the structure will try and repel itself and condensing it will be harder. With this evidence it seems quite likely that Ca2+ is responsible for maintaining the structure of chromosomes in order that their carrier cell may reproduce and the lack of it will hamper the cells progress.


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