How do mutations occur in human beings?

29 January 2012

Question

Hi Naked Scientists
My question is- how do mutations occur in human beings?

Answer

Mutations are damage to the DNA of your cells. DNA is obviously the instructions for your cells, telling them what to do, so damage to DNA in your cells can cause problems. Most mutations happen because we breathe oxygen. But don't stop breathing, you'll probably going to be okay! Breathing oxygen generates molecules called free radicals within ourselves and these are very damaging to DNA. Most of the mutations that we get are just patched up all the time. We have very good DNA repair processes in our cells that fix them, but sometimes mistakes creep in. Most of the time, these aren't even important because a lot of the cells in your body are destroyed after a while. The cells in your gut are constantly turning over, also in your skin, and your bone marrow... So most of the time, mutations are not that important. Cells get damaged and they just die and you get rid of them. What happens when it becomes really important is when you get mutations in cells that do hang around and in stem cells particularly that can cause problems. But there are lots of other ways that you can mutate the DNA in your cells. For example, the carcinogens, the cancer causing chemicals and things like tobacco smoke. Some things in our environment, some things like benzenes, some air pollution, all sorts of things can damage your DNA. Another big cause is the Sun. The ultraviolet light from the Sun causes a very specific type of DNA mutation. It causes the Thymine bases (the 'T's') that are nearby to fuse together in your DNA.

So there's an awful lot of things that can cause mutations. Sometimes they don't matter, sometimes they do. Some of which we can't prevent and a lot of which, our body just repairs naturally. But the trouble is, when we don't repair them or we keep piling more mutations, or if we have problems with the repair systems in our cells, then you can get problems like cancer and other diseases.

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