Ever been defeated by a particularly tricky bit of flat-pack furniture? Even our cells struggle with DIY sometimes. Within a dividing cell, matching pairs of chromosomes must join up to exchange sections of DNA. This is a delicate process, and if the chromosomes fail to join or separate properly, new cells can end up with serious genetic abnormalities. Some complications are caused by structural faults in a molecular ‘velcro’ called cohesin, which holds the two chromosomes together. The chromosome pairs pictured come from dividing egg cells from mice lacking part of cohesin. In each case complete pairing has been disrupted: by a ‘fork’ (top left) ‘bubbles’ (top right and bottom left) or by failure to join altogether (bottom right). Knowing the crucial role of cohesin is a step towards understanding why some pregnancies fail in the early stages, as egg cells with chromosomal defects rarely survive for long after fertilisation.
Written by Emma Stoye
BPoD stands for Biomedical Picture of the Day. Managed by the MRC London Institute of Medical Sciences the website aims to engage everyone, young and old, in the wonders of biomedicine. Images are kindly provided for inclusion on this website through the generosity of scientists across the globe.
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