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cells

  • 07-01-2008 2:05pm
    #1
    ronbyrne2005
    Closed Accounts Posts: 3,494 ✭✭✭


    How does a cell know what type of cell it is and how do stem cells know what cells to become? For example how does a neuron know to perform the duties of a neuron or a skin cell know to behave as a skin cell?


Comments

  • #2
    Kevster
    Closed Accounts Posts: 2,980 ✭✭✭Kevster


    As far as I know, a Stem Cell receives extracellular signals that transduce messages to the nucleus of the cell. This causes certain portions of the DNA of that cell to be transcribed and, from there, the cell assumes a certain role.

    The extracellular signals would come from other cells in the body and would include chemicals such as hormones.

    That's it explained very simply.


  • #3
    John
    Registered Users, Registered Users 2 Posts: 12,135 ✭✭✭✭John


    It's a fairly complicated process. All cells in the body come from a fertilised egg (one cell). In the fertilised egg the chemicals present do not exist in equal concentrations all over the egg, instead more of protein A will be at the top and more of protein B will be at the bottom so you have gradients formed across the egg. When the egg starts to divide, the protein will be divided unequally into the daughter cells and different levels of different proteins will result in these daughter cells acting differently to each other. These are all stem cells and can be theoretically be turned into any type of cell by human intervention.

    As these stem cells divide, different combinations of proteins will be present (and new ones formed, older ones turned off depending on the cell) and the cells will start to communicate with each other. Eventually populations of stem cells will be formed where a given population becomes locked into a particular fate (neuronal stem cells (where they can form any type of neuron), muscle stem cells (where they can form any type of muscle cell) and so on). With evey division and cell interaction the daughter cells become more and more specialised until eventually they form the different cells that make up your body.

    Essentially at the end of the day, cell determination relies on a few factors:
    1) Combination of genes expressed.
    2) The time during development at which they are expressed.
    3) The sequence in which they are expressed.

    This is a very brief and vague outline of the situation, if you are really interested and have a little while on your hands you should explore the website for the book Developmental Biology (one of the classic dev bio textbooks for college) or the wikipedia page for a clear overview of the area.


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