• Question: What do mitochondria do? (and are they actually pink?)

    Asked by kattypuss to Rachael, Penny, Jennifer, Jean-Paul, David, Dave, Alison on 6 Jan 2014.
    • Photo: David Bowkett

      David Bowkett answered on 6 Jan 2014:


      The main roll of mitochondria is to make a molecule called ATP (its stands for Adenosine TriPhosphate, but is almost always shortened to ATP). ATP is used to carry energy around the cell. When a cellular process requires energy, ATP will be converted to another molecule called ADP (Adenosine DiPhosphate). This conversion gives off energy which can be used by to power many different kinds of events within a cell. For this reason, mitochiondira are often referred to as the “power plants” of the cell.

      Mitochondria aren’t pink, the reason they would appear pink in an image is because a pink dye has been used to make the mitochondria show up under a microscope.

    • Photo: Penelope Mason

      Penelope Mason answered on 6 Jan 2014:


      The short answer: a lot, but mainly they are the “power stations” of the cell. They are small factories for transforming energy from the food you ingest into a form of energy that the cell can easily use. Long answer: Mitochondria have a double membrane surrounding them and the inner membrane has lots of proteins sticking in it that form the electron transport chain. A complicated system called oxidative phosphorylation passes electron energy down the electron transport chain to drive the final protein called ATP synthase (I.e. the protein that synthesises or makes ATP). This protein uses the energy to stick an extra phosphate group onto a molecule called adenosine diphosphate (ADP) to make it triphosphate (ATP) I.e. Ad-P-P to Ad-P-P-P. The energy is stored in the bond (the final hyphen between the two P’s) and the small easily moveable ATP molecule can now go away to wherever it’s needed. Breaking the bond and making Ad-P-P and a single P releases the energy back to the cell.
      Mitochondria also have lots of other functions, but perhaps the most important is in programmed cell death, when a cell is instructed to die by the body. One of the first things the death instruction does is to signal mitochondria. This happens by causing lots of calcium to go into the mitochondria and disrupt them, so they release lots of their own proteins such as cytochrome c (part of the electron transport chain) into the rest of the cell. This is a message for all the rest of the cell to start destruction.

    • Photo: David Christensen

      David Christensen answered on 6 Jan 2014:


      The others have given good answers and they’re right about mitochondria being needed to produce energy for the cell, but I’ll add a bit more, which is related to my work.

      I work with embryonic stem cells, which, interestingly, have very few, under-developed mitochondria and use very little oxygen (which is normally needed by mitochondria for energy production). This means that embryonic stem cells produce very little energy and presumably require very little energy, which is surprising because they divide faster than many other cell-types. In my lab, we are looking at where embryonic stem cells get the energy they need, without mitochondria. If we can understand better how they use nutrients to produce energy and build everything they need to divide, then we might be able to more easily use embryonic stem cells in treatments for many different diseases.

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