Mitotic Cell Division Made More Clear

At any given moment thousands of cells are dividing by Mitosis in our bodies. During Mitosis the cell duplicates its genetic material and divides itself into two identical halves. If this process does not work efficiently it can lead to mutations which can cause diseases like cancer. A research on this complex mechanism was carried out by Manuel Mendoza and his team from Centre for Genomic Regulation (CRG) using yeast.

Mitotic Division in Cells 

When a cell prepares to divide, it duplicates its DNA into pairs of identical chromosomes. This chromosomes are tangled and twisted amongst themselves. For a cell division to occur, this twisted chromosomes have to be untangled, and that is where the enzyme Topoisomerase 2 (Topo 2) comes into play. Topo 2 cuts the DNA knots, untangles the knots between replicated chromosomes, and then ties back the ends afterwards so each pair of chromosome can migrate to the opposite ends of the cell.

It was thought that Topo 2 acted quickly and equally on all the chromosomes. But it was found that longer chromosomes need extra help to undo the knots. This extra help to Topo 2 is given by microtubules. Microtubules anchor to the chromosomes at a precise point and pull them apart towards opposite ends, so each cell gets its individual copy.

Mendoza and his research team noticed the speed at which the microtubules  pull the chromosome apart was constant. But, when a shorter chromosomes was under tension it would be untangled rapidly, on the other hand a longer chromosome took more time to come under tension (due to its long length), and therefore Topo 2 would finish untangling them for a longer time. The untangling only occurs when the microtubules begin to stretch the chromosomes (anaphase). Right up to that moment Topo 2 keeps doing its job.

It is surprising to know that not everything yet has been known about the Mitotic cell division as it is a  repetitive mechanism that has been occurring in our bodies from the beginning of time. I think it is essential that everything about it should be known, and this discovery about the role of Topoisomerase 2 is step towards knowing the proper functioning of cell division and hence higher survival of all the cells, and living beings.



Article: http://www.sciencedaily.com/releases/2014/09/140916101958.htm
Related Article: Mitosis -  http://www.nature.com/scitable/topicpage/mitosis-14046258