How can radiation change our DNA?


How can radiation change our DNA?


The radiation itself doesn’t actually change our DNA, it damages it. Radiation is very high energy, so it can ionise our DNA, i.e. it can knock electrons off our DNA thus breaking bonds holding it together. Our body tries to repair that damage, but sometimes does it badly or makes mistakes, and the result can be cancerous cells.

Radiation causes ionisation of particles (e.g. turning an atom into an ion – i.e. changing the charge of the particle). When particles are ionised, their properties change, and their interactions with other particles will change.

When those particles make up a substance, for example DNA strands, the substance will be damaged because it will start to “break apart” for want of a better phrase.

DNA can also be damaged when the water in the cell containing the DNA gets ionised, which releases free radicals (particles with an unpaired electron, and highly unstable) that in turn damage DNA by reacting with it.

Your DNA is a big molecule.

The atoms that make up a molecule are held together by sharing electrons. How they are sharing electrons determines the shape of the molecule the atoms are forming. The positive charge of the atoms and the negative charge of their electrons normally balances out.

Some types of radiation can knock electrons away from atoms. These are called ionizing radiation.

When the electron goes missing the atom is positively charged. Then chemistry happens until all involved atoms and the electrons they share end up being in balance again charge-wise.

The resulting molecules may not be the same as the ones before the whole thing happens.

You may think of radiation hitting your DNA like bullets from a gun hitting a blueprint.

Sometimes the holes they make make no difference, sometimes it means that nothing gets build at all. 99% of the time the foreman holding the blueprint notices that something is wrong and drops the blueprint in the trash and uses a different copy.

If you are really unlucky chance made the bullet hit in just the right way to make a meaningful change and nobody notices and they build based on the wrong blueprint.

This is how you can get cancer.

Of course if you are really lucky the hit may have been in one of the cells that you use to pass on your genes to your offspring and the change made is actually something that makes the offspring slightly more likely to pass on their genes. Then you get evolution instead of cancer.

You watched Chernobyl, didn’t you?

Thymine dimers? I know it’s a result of ultraviolet radiation, causes adjacent thymine nucleotides to bond to each other rather than bonding to the adenine on the anti parallel strand.