Making new cells - Separating and dividing

cytokinesis diagram Before a cell can finally divide, it needs to make sure that the copied DNA will be shared equally between the two 'daughter' cells. To do this, pairs of chromosomes line up along the spindle and are pulled apart to opposite ends of the cell.

Up until this point, the pairs of chromosomes are held together by a molecular ‘glue’ called cohesin. This breaks down when it’s time for the chromosomes to separate. If cohesin doesn’t work properly, the daughter cells can end up with the wrong number of chromosomes, which may lead to cancer.

Once the chromosomes have separated, the cell’s internal 'scaffolding' - known as the cytoskeleton - forms a molecular 'belt' around the middle of the cell. This tightens and pinches the membrane surrounding the cell, until it splits in two. This final step, when the cell splits to form two new ‘daughter’ cells, is called cytokinesis.

Studying the ‘glue’

Going separate ways

Professor Kim Nasmyth and Dr Frank Uhlmann are world experts in this field, discovering cohesin in 1997 by studying yeast cells. Although it may seem surprising, many of the molecules involved in cell division are very similar in yeast and humans.

Recently, Professor Nasmyth and his team made a groundbreaking discovery about the way cohesin holds chromosomes. They showed that it forms a ring, trapping the chromosomes inside until it's time to separate. This pioneering work has opened up a whole new field of exploration for researchers, allowing them to gain deeper insights into how chromosomes separate.

And we’ve funded the work of award-winning scientist Dr Frank Uhlmann and his team at our London Research Institute for nearly a decade. Along the way they have made important discoveries about how chromosomes separate in yeast – in particular unravelling the role of an important molecule called separase, first discovered by Dr Uhlmann in 1999.

Dividing cells Problems in cytokinesis – when the cell finally splits to form two separate cells – are linked to cancer. So understanding more about the complicated processes involved could pave the way for new cancer treatments.

Our researchers are making great strides in understanding how cells split. At our London Research Institute, Dr Mark Petronczki is exploring cytokinesis in human cells, focusing on the 'motors' that tighten the 'belt' around the middle of a dividing cell.

And Professor Francis Barr in Liverpool is studying the molecules involved in cytokinesis in yeast cells. He and his team are using powerful microscopes to study where these molecules are located, and how they move around in living cells. This will enable the researchers to see what happens in cells when some of these molecules are faulty.