• Question: what is rna

    Asked by teamnicedynamite to PB on 25 Jun 2013.
    • Photo: Peter Balfe

      Peter Balfe answered on 25 Jun 2013:

      Here’s an answer way above GCSE level!
      You’re doubtless familiar with the “word” DNA…
      Which stands for Deoxyribo-Nucleic Acid.
      This compound word describes a 2-part molecular structure, the bit we call a base (you may even know their 4 labels : A, C, G and T) and the other bit, which is a backbone joining all the bases together and is made of a 5 carbon sugar called Deoxyribose.
      Deoxyribose is almost identical to the sugar called Ribose, but with a H instead of an OH group on one of the carbons, meaning it’s short by one oxygen, hence the name! So there you go, RNA/DNA- done!

      But why bother with two? Like many things in life it all boils down to cost.
      RNA is inherently less stable than DNA, which means it is easy and cheap to recycle, and so is used for copying (transcribing) information out from chromosome DNA to the cytoplasm where it can be turned into proteins etc.. This messenger RNA can be rapidly broken down after use and the bits shunted back. The bonds in DNA are way more stable than in RNA and so the energy used to recycle them would be much higher.

      Some viruses (like “my” virus HCV) are made of RNA instead of DNA, allowing them to dodge all that high energy overhead of keeping DNA copies of everything. The downside is they’re made of a very fragile and unstable chemical, so they tend to be small and mutate and change like crazy. But as a “lifestyle choice” for these viruses it works just fine.

Comments

  • Photo: Paul

    Paul commented on :

    wow- I’m going to write that down…

  • Photo: Lyn

    Lyn commented on :

    The old dogma – ‘DNA makes RNA makes protein’ 😉

    It’s not always true anymore, because we now know that a lot of the RNA in our cells don’t always go on to make protein, but generally speaking – if you think of DNA as a huge library, then RNA is the photocopies you make in the library and take away with you (cheaper and less stable, as Peter said), so that you can follow what’s written on them to make the cell do what it should!