• Question: how small are strings of DNA ?

    Asked by my1es0d to Jamie, Jodie, Kat, Mark, Niamh on 16 Mar 2011 in Categories: .
    • Photo: Jamie Pringle

      Jamie Pringle answered on 15 Mar 2011:

      Hello my1oes0d,

      Biology is not my strong suit, maybe one of my colleagues could assist? Basically DNA contains the genetic instructions for all living organisms and is super tiny, how small, I dont even know!

      There is more information on DNA here: http://www.bbc.co.uk/schools/gcsebitesize/science/edexcel/genes/dnarev1.shtml

    • Photo: Mark Hill

      Mark Hill answered on 16 Mar 2011:

      Hello my1es0d,

      An interesting question. I think this really is within Kat’s expertise. All that I know is that they are extremely large, long-chain molecules, that are nonetheless still nanometres in size. I look forward to other answers to this question.

      Thanks,
      Mark

    • Photo: Katherine Davies

      Katherine Davies answered on 16 Mar 2011:

      Hi Myles

      There length of DNA in every cell (except red blood cells) in the body is about a metre long. Can you imagine how small this has to be wrapped up to fit it all in? DNA is wrapped around proteins called histones, which are coiled up into chromosomes (we have 23 pairs, one each from mum and dad).

      If you get a piece of string, hold both ends and twist it by one end until you cant any more, you will see it coil up into a ball, thats a bit like what happens to DNA.

    • Photo: Jodie Dunnett

      Jodie Dunnett answered on 16 Mar 2011:

      I think that they are only a couple of nanometers in width . Sorry, I’m a chemist so a biologist might have a better answer for you 🙂

    • Photo: Niamh Nic Daeid

      Niamh Nic Daeid answered on 16 Mar 2011:

      HI Myles

      According to some work that has been published the nucleotides (which are the building blocks of DNA) are about 0.3 nanometers long, thats about three hundred thousandth of a meter. DNA is a polymer so its a long chain of nucleotides stuck together. The length of the DNA chain depends on how many nucleotides are present and I think Kat mentioned the average length in a human cell.

      When you do DNA analysis you multiply the strands of DNA so that you get lots of material to test.

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