The Mystery Of Cell Division

Scientists have been trying to understand how cells are built since the 1800s. This does not surprise us and, as scientists ourselves, we have always been puzzled at how cells, such complex structures, are able to reproduce over and over again. Even more astonishing is that, despite the frequency of cell division, mistakes are relatively rare and almost always corrected.

According to Professor David Morgan from University of California, the complexity that we observe in cells can be compared to that of airplanes. Similarly to what happens in planes, cells are composed of many different components, each one responsible for performing a certain function. Despite this similarity, there is also a striking difference: contrary to human-made machines, cells havetheabilitytoself-reproduce. But how does this cell reproduction happen and how is it controlled? What needs to happen for a cell to divide?

Cells are social entities that only divide when necessary. Most cases of cell division happen in one of three scenarios: when our bodies are growing, when we wound ourselves and need to repair our tissues, or in tissues like our skin and gut in which cells are constantly being shed and replaced. This controlled cell division is, however, lost in cancer: one of the underlying principles of cancer is that cells keep on dividing when or where they should not and, therefore, can generate tumours.

Before each division cells need to duplicate each of their components. This duplication is essential to guarantee that the daughter cells are exactly like their mother. A crucial step during this duplication is the step of copying the genome, containing all the genes of the cell. Genes are located within chromosomes, X shaped structures. After duplication of the genome, each chromosome is bound to its sister chromosome by a glue-like substance. During cell division this glue is destroyed and rope-like structures pull the sister chromosomes to opposite end of the cell. In this way each pole of the cell will contain a whole set of chromosomes and can, therefore, become a new daughter cell.

It is important to remember that these processes have to happen in a sequential manner. Socks first, shoes later, right? There are switches in the cell that have to be turned ON or OFF before the cell can move on to the next step. These switches allow for cell division to be such an accurate process.

Professor David Morgan specialises in this complex control system. He focuses his work on cyclin-dependent protein kinases (Cdks). These highly conserved enzymes are activated at specific cell cycle stages and are directly responsible for starting major cell cycle events such as DNA duplication and separation of sister chromosomes.

Source

Cosy Science - Getty ScienceThis article has been inspired by a talk given by David Morgan, a Professor at the University of California, San Francisco, who shed some light on fascinating process of cell division during his talk in London this May. Text has been brought to you by Mariana Campos from Cosy Science, an organiser of monthly informal events where the hottest topics in science are discussed with people of various backgrounds over a beer or a glass of wine.

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