• Question: do each of our body cells carry the same genes?

    Asked by rozzadee to Amelia, Jim, Liz, Prateek, Richard on 20 Jun 2011.
    • Photo: Prateek Buch

      Prateek Buch answered on 19 Jun 2011:

      good question. Yes they do – all apart from gametes (sperm and eggs). They all carry the same genes, but different parts of the body switch on different genes – when I say switch on, I mean they use different genes to make proteins from. This way, all cells have the gene for rhodopsin (the pigment that sense light), but only rod cells in the retina at the back of the eye actually switch on the gene and so only these cells actually have rhodopsin protein. Hope that helps 🙂

    • Photo: Richard Badge

      Richard Badge answered on 19 Jun 2011:

      A very good question and well covered by Prateek, but there are some interesting exceptions…

      Human red blood cells lose their nucleus and mitichondria in the later stages of their development (to make more room for oxygen carrying haemoglobin) and so don’t contain any DNA (or genes) at all.

      When the white blood cells that enable your immune system to recognise pathogens like viruses and bacteria (to help your body fight infections) develop they rearrange their genes in a programmed way to make many millions of different variations. These variations produce millions of different proteins one of which might recognise a pathogen your body has never been exposed to, which is a neat trick. This immune cell genetic variation means that the cells are all a little bit different…

      (As an aside the rearrangement process involves a DNA cutting and pasting enzyme that was likely stolen from a jumping gene – the type of DNA that I work on!)

    • Photo: Lizzard O'Day

      Lizzard O'Day answered on 20 Jun 2011:

      yes’m. Each body in your cell has the exact same copy of DNA- (barring any mutations). However the cool thing is that not every cell turns on every gene. Muscle cells turn on muscle genes, heart cells turn on heart genes and the like. Interestingly you may wonder what happens if a heart cell starts expressing muscle genes- well except in rare cases they really don’t- once a cell decides what it wants to be- that’s what it is– it’s as we scientists say “committed” to a particular fate. Some fancy science is going towards reprograming where you can try to persuade a cell to change into something new– but this is still an area of active research.

    • Photo: Jim Caryl

      Jim Caryl answered on 20 Jun 2011:

      It’s also important to consider all the other genes that keep your body healthy, as they don’t all belong to you.

      We are covered in bacteria, in fact we have 10 bacteria cells on (and in) our bodies for every one of our own cells. They’re much smaller than our cells, which is why you look like a human rather than a big blob.

      These bacteria are essential to our health, they help protect our skin, and your gut. They also help digest some of your food. To do this they use lots of different genes, hundreds of which are totally different to our own, so you have thousands more genes involved in your health, none of which are actually yours.

      Different parts of the body have different bacteria, so there will be differences in the genes at different parts of your body.

      So whilst you are very much human, you are helped along by the many bacteria on you too. Pretty amazing eh?

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