DNA repair- Why should you care?

Difficulty: 1 (Easy)

photo credit: blarfiejandro via photopin cc

photo credit: blarfiejandro via photopin cc

DNA (dioxyribonucleic acid) is the genetic map that defines who we are.  It’s found in the nucleus of every one of our cells, and is made up of a number of different bases which when put together code for every action our cells take.  Whether it’s producing an enzyme which breaks down starch (an Amylase) or an antibacterial (such as Lysozyme), everything we do is governed by our DNA.  But what happens when this gets damaged?  Imagine your genome is a set of really complicated instructions, but a page has been torn out.  How do you know what to do?  Thankfully our DNA exists as a double helix (Have a look at the picture to the right if you’re not sure what that looks like), so you have two copies of each strand.  To go back to the metaphor before, essentially you have two copies of the instructions!  To complicate matters a little further, both of the strands of DNA aren’t actually identical but are complementary.  This means that each base pairs specifically to another base (A-T, C-G), so what you have is a mirror image of your information.  It’s therefore pretty unlikely that any damage that is made can’t be fixed.

Why should you care about DNA damage anyway?

The human mitochondrion has 16,569 base pairs, never mind the staggering 3.3 x 109 base pairs that make up our entire genome!  So what if one base is changed?!  Well, unfortunately that one base change, if coding for an important gene, could have a catastrophic effect on your cells.  Variations in proteins that control the cell cycle could cause cancer.  Furthermore, too much DNA damage is a signal to the cell that it needs to induce apoptosis (cell death).  Often damage causes changes in the shape of DNA, making it distorted, and this in turn can cause more problems when your cells try to replicate.  Terrifyingly, our cells are faced with these problems thousands of times a day, but thankfully we have evolved to be very good at noticing these changes and fixing them.

What causes DNA damage?

Far too many things to mention!  Naturally damage occurs to DNA all the time, and often on purpose. For example, topoisomerases are proteins which stop over-winding of DNA during replication by cutting one strand and allowing the other to pass through.  This would cause huge problems to your cells when they are replicating their DNA (a crucial process), so proteins like this have a very important role.  There are other mutagens that can harm our DNA, from radiation to harmful chemicals.  Imagine a world where every time you got sunburn you developed cancer… Thankfully this isn’t the case, thanks to some clever tricks our cells have evolved to fix this.

So that’s a quick overview of why DNA damage happens and what causes it.  Over this series of blogs I’ll talk more about the causes of damage and specific ways organisms have adapted to fix these problems.

I hope you’ve enjoyed your daily dose of science!

Amy

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