Medical Research Council - London Institute of Medical Sciences

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16 June 2015

Unequal Shares

Organising, maintaining and replicating DNA is a complex process, and any problems can have severe repercussions. In human cells, DNA is normally packaged into 46 structures, or chromosomes; each time a cell divides, these chromosomes are aligned, replicated, then symmetrically pulled apart into each of the daughter cells. Errors in this process generate cells with an abnormal number of chromosomes, a phenomenon known as aneuploidy. A common cause of miscarriages and birth defects when it occurs in reproductive cells, aneuploidy also arises in cancer cells. It then often leads to further chromosome instability, causing an unequal distribution of chromosomes during subsequent cell divisions – in the example here, one chromosome lags behind in the division process and is then incorrectly sorted. Aneuploidy and chromosome instability in cancerous cells may be linked to advantages such as greater drug resistance, so a better understanding of these processes is essential to developing effective treatments.

Written by Emmanuelle Briolat

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