• Question: Is all of our genetic information in every cell in our body (that has a nucleus)? And are all our genes active in every cell, or does it depend?

    Asked by abiiii on 1 May 2020.
    • Photo: Mery Shahin

      Mery Shahin answered on 1 May 2020:

      That is a great question! All cells in our body that have a nucleus contain all of our genetic information – all 46 chromosome, with the exception of the egg and sperm cells which contain only 23 chromosomes. This is because the sperm and the egg combine to make the zygote which has 46 chromosomes.

      Even though cells contain all of the genetic information that doesn’t mean that all genes are active in every cells. Cells are specialised – there are liver cells, heart cells, neuron cells, muscle cells, skin cells. These cells have different functions and morphology which is dictated by the genes that are active in those cells. So in skin cells different sets of genes will be active to the genes in a liver cells.

    • Photo: Kim Liu

      Kim Liu answered on 1 May 2020: last edited 1 May 2020 11:48 am

      Great question – yes, each cell contains all the information required to make a human! I think the only exception is red blood cells which don’t have a nucleus. And exactly as Mery says, which genes are active determines what kind of cells they are. Sometimes, if the wrong genes activate at the wrong times, and they can cause disease.
      The next question might be could you convert one cell type into another if you could turn on/off the correct genes? The answer is yes – how much do you know about stem cells? 🙂

    • Photo: Lidia Ripoll Sanchez

      Lidia Ripoll Sanchez answered on 1 May 2020:

      Hello, that’s a very interesting questions. As Mery said all cells in our body, but germ line cells that have 23, have 46 chromosomes. And as cells are specialised they have different genes active. Also cells have a cell cycle, their own life cycle inside our tissues, by which they grow, divide themselves to form new cells and die. At each stage of the cycle the cell also activates different genes. Other situations that can make cells activate or deactivate genes are situations of stress, for example a disease like cancer.

    • Photo: anon

      anon answered on 1 May 2020:

      As the other scientists have said all our genetic information is in every cell of our body that has a nucleus. But not all that genetic information is active. When I was learning this at school one helpful analogy I found was that cells in your heart and brain have very different jobs to do. In order to do those different jobs they need different machinery and so different genes are active to supply the different machinery (proteins) those cells need to do their specialised jobs.

      Sometimes the job of those cells can change over time and so different genes will become turned on and off in response to the changing needs of the cell.

    • Photo: Andrew Beale

      Andrew Beale answered on 1 May 2020:

      Others have covered this, but just a mention for somatic recombination (https://en.wikipedia.org/wiki/Somatic_recombination) where some cells in the body do actually have different genetic information because they have rearranged their DNA for a special purpose – like in the lymphocyte white blood cells to allow our immune system to adapt.

    • Photo: Nina Rzechorzek

      Nina Rzechorzek answered on 1 May 2020:

      Hey Abiiii – really important question, and answered well by the others. Just to add that even in cells of the same type, the activity (expression level) of their genes will vary by time of day – and that helps to coordinate the ‘cellular clock’. There are daily rhythms in gene activity in all nucleated cells, but red blood cells (without a nucleus) still have daily rhythms in other things so they still have their own ‘clock’!

    • Photo: Maria Marti

      Maria Marti answered on 1 May 2020:

      You already got very good answers! Just to add a bit more information, you have to think that, even if all our cells have the same information, we use some of it almost continuously and some of it only very briefly or in case of emergency. Some of our genes, for instance, are very important during our development in the womb, as our bodies are still forming, and not that useful once we are born. To control that, different cells open up different regions from our DNA to read from them and perform their functions. The other regions tend to be nicely compacted so that they don’t take up much space in our cell nucleus and only open up when we need to copy all of our genes to pass them to a new cell.

    • Photo: Ozge Ozkaya

      Ozge Ozkaya answered on 5 May 2020:

      Yes the genetic information is always there, but no not everything is always active.