• Question: How is that the cell maintains internal order, yet it discharges heat (disorder) to the surrounding?

    Asked by Andrea to Eoin, Ester, Ildiko, Natasha, Paul, Tom on 14 Nov 2017.
    • Photo: Eoin McKinney

      Eoin McKinney answered on 14 Nov 2017:

      You’re absolutely right that the cell is tightly regulated. Every part of it has to be kept under control to prevent it dying or – worse – turning into a cancer cell that divides uncontrollably. Producing heat isn’t necessarily disorder, if that process is also controlled and the heat is useful. Heat is another form of energy and is useful to maintain protein function. the body carefully regualtes heat production by altering the cells’ metabolic rates using hormones (chemicals released from a part of the brain called they hypothalamus).

    • Photo: Natasha Myhill

      Natasha Myhill answered on 14 Nov 2017:

      Yeah, as Eoin says, producing heat is quite normal. Our whole body works to regulate our overall temperature anyway so thats not a problem for us. A cell does maintain a strong internal order but it does also regulate its environment and its external surface, to make sure the cell is working properly, as well as the cells around it.

    • Photo: Paul McKeegan

      Paul McKeegan answered on 16 Nov 2017:

      That is a question I once had in a tutorial during my degree. The whole universe tends towards disorder, so biological systems like cells that maintain order are really incredible.
      The release of energy from food in cells, or cell metabolism, is basically a biochemically controlled set of reactions that do the same thing as burning. But instead of all the energy being released as heat, the energy is released in little bits, step by step. This means it can be stored in the form of a molecule called ATP, and carried where it needs to go within the cell or elsewhere in the body.
      But metabolism does release a little bit of heat. Most of the energy we get from food breakdown is done by a process called oxidative phosphorylation which happens inside mitochondria. Its a complicated set of reactions which allow the maximum possible ATP to be produced for every molecule of food. The breakdown of the food molecule is coupled to the production of ATP in an unusual way, so there is some ‘waste’ in every cell, giving off a bit of heat.
      Some cells use this as part of their normal function – fat tissue called brown adipose tissue is made up of cells with lots of mitochondria that give off lots of heat. Babies have lots of this tissue to help keep them warm, but adults have much less. We tend to have warm patches of this tissue at the base of our necks and around our shoulder blades.

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