• Question: How big r the things u study?

    Asked by to Claire on 16 Jun 2014. This question was also asked by .
    • Photo: Claire Shooter

      Claire Shooter answered on 16 Jun 2014:

      Well I study genetics so I suppose it’s big in one way and small in another…
      Every single cell in your body contains all the instructions necessary to make and operate you in the form of DNA. The instructions are made out of sequences of four different molecules which we label ‘A’ ‘G’ ‘C’ and ‘T’. The human genome is like a manual written in a language that only uses these four letters. Cells are around 10-100 micrometres which is very small indeed, and the nucleus which contains all this DNA is only 6 micrometres across!
      I study how mistakes in the DNA sequence can affect how your blood cells function. Normally this means I extract DNA from a few millilitres of blood and analyse about three micrograms of it. That’s about a tenth of the weight of one grain of rice. Again, this sounds like a really small amount, but that’s actually around 3 million copies of your genome, each from a different cell.
      So, I work with what seems like a tiny amount of a tiny thing, but when I come to analyse all that DNA I end up with about 3 Gigabytes of data, which is all just the A/G/C/T sequences of little bits of DNA. The 3 Gigabytes is about 25 billion letters! If I wrote that out in MS word in size 10 Arial it would be a million pages long. Thankfully, I don’t have to do that – there are lots of clever programmes I can use that help me put all the DNA in order, and look at it from lots of interesting angles.
      So what I physically look at is microscopic, but the data I actually get out of it is huge!

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