Question: If you get an injury or disease what happens to the cells in order for them to need to mend themselves?

Sam Godfrey answered on 22 Nov 2012:

Well often the cell realises it has a disease and does one of three things. It either commits suicide in a process called apoptosis. (it does this when cells get old as well). Or it calls over certain types of white blood cell which kill the cell. Or if the damage isn’t too bad, it switches on these genes which start up special repair machinery. Sometimes it is a simple repair like making new bits of the cell that got lost. Sometimes they have to read all their DNA and look out for mistakes. If the cell does die, a neighbouring healthy cell will make a copy of itself and the new cell will take the place of the old. This is a really important bit of science, because if we can understand this properly we can use it to help in many diseases, and also fight against it in cases of cancer where this process goes wrong.