I know that the mitochondria is basically the power house of the body, it consumes amino acids, fatty acids, glucose, etc and oxygen.

When these molecules meet up in a enzyme, a series of reactions happen (Krebs cicle) which end up in CO2, H20 and energy.

Then the enzyme and later mitochondria will release its energy which will be stored in ATP molecules.

My question is what is this energy?


closed as unclear what you're asking by fileunderwater, kmm, rg255, WYSIWYG Oct 22 '16 at 6:14

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  • $\begingroup$ If your question is "what is energy"; then it is a purely physics question. Whom we call energy in physics, the same thing we call as energy in biology. Energy is a concept. It means 'ability to do work'. or in simple words, restlessness. Or unstability. A running bulette contains some energy so it can break an wall. As well if you keep a book on a table; it 'stores' some energy hidden in it. If instead a table you put the book on a thin glass sheet with support only at edge; it would broken. The energy came out. $\endgroup$ – Always Confused Oct 13 '16 at 12:52
  • $\begingroup$ Experimental result shown when an object do an work on another; the energy levels change, but that no energy get 'annihilated' or 'born'. It just 'dissipated to' / 'come from' the other object. Same for chemical reactions (molecular works). $\endgroup$ – Always Confused Oct 13 '16 at 12:58
  • $\begingroup$ Quite in a manner of macroscopic objects, chemical molecules can give/ take/ store energy. When a chemical/physico-chemical 'change' occurres on a molecule; that means at the same time release or intake of some energy. To make/ break a chemical bond, or to do change in a bond-length or a bond angle or to rotate a group around a bond to change a dihedral angle, or to transport a molecule/ ion from one-side of membrane to another side... each process give or take some energy. $\endgroup$ – Always Confused Oct 13 '16 at 13:27
  • $\begingroup$ The very wrong thing I see in your question is, "Then the enzyme and later mitochondria will release its energy which will be stored in ATP molecules.". From where you came to know that? At each step of each and every chemical reaction there is some energy-change in the molecular structures; and when one system release some energy, at the same time some other system take the energy.You raising a bottle that means you are adding some energy at the same time... not 5 minutes latter. Usually energy doesn't exist without matter. (except radiation or EMW).Heat-energy is too molecular vibrations $\endgroup$ – Always Confused Oct 13 '16 at 13:42
  • $\begingroup$ And EMWs (electromagnetic waves) would NOT persist more than moment. They'll enter some or some interaction with matter (molecules). The function of ATP is; when at some steps of respiration-reactions release burst-amount of energy; an energy-taking reaction (ADP+Pi --- > ATP) take place with help of special molecular machinery. ATP is a molecule, so it can be transported. Later-on where in cell the energy is required for any molecular work, the reverse reaction (ATP --- > ADP+Pi) take place, the energy come out. $\endgroup$ – Always Confused Oct 13 '16 at 13:54

ATP is a form of chemical energy. Hydrolysis of the third phosphate group produces quite a bit of energy:

ΔG° = −30.5 kJ/mol (−7.3 kcal/mol)

ATP is used in a variety of cellular processes, from signal transduction to biosynthetic reactions, motility, and cell division.

An interesting bonus fact: an adult human body only contains about 250 grams of ATP at any one time, but turns over its entire body weight in ATP during the course of a single day.

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    $\begingroup$ nice fact, we basically run on 250 gram "battery" but my question is "what is energy?" $\endgroup$ – aurelius Oct 12 '16 at 18:35
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    $\begingroup$ @aurelius I don't understand your question, then. The energy is stored in the phosphate bonds of ATP - it's chemical energy. It can then be converted to mechanical energy, heat, electrical energy (neuron impulses), etc. $\endgroup$ – MattDMo Oct 12 '16 at 18:36
  • $\begingroup$ my question was this but I couldn't express it right so I tried it again here if you are curious: skeptics.stackexchange.com/questions/35461/what-is-energy $\endgroup$ – aurelius Oct 12 '16 at 19:04

The use of the energy in ATP is quite complex. Since my college days our knowledge of how ATP is used has broadened considerably.

Let's look first at the role of ATP in the sodium-potassium pump. This pump uses roughly 20% of the ATP your body produces, even more if you are a couch potato. ATP powers this process by attaching its terminal phosphate group to the pump. The phosphate group is highly charged. Its attachment pulls and tugs on some regions of the pump and repels other regions due to the fact that many of the amino acids comprising the pump are polar or charged. These electrical, magnetic-like, interactions change the shape of the pump. This causes sodium ions to be pumped outside the cell even though they are more plentiful there. When the phosphate is released, the pump returns to its original shape bringing in potassium ions and reloading sodium. It is this pumping action that, among other things, provides the energy for messages in nerve and muscle cells (action potentials).

Probably the important energy use of ATP is this. Many of the reactions your body needs are uphill battles. That is, there is more energy in the substances we wish to produce (products) than in the substances which we must use for raw materials (reactants). So, the ATP attaches its phosphate to the reactant. This raises the energy in the reactant making it now have more energy (more unstable) than the product we wish to produce. The reaction now becomes "downhill" and can proceed naturally ("spontaneously") without holding a bunsen burner under your bottom. This concept is termed "coupled reactions" where we take the "downhill" breaking down of ATP and use it to power the "uphill" production of a requires substance.

There are two principal reasons a molecule becomes more energetic when a phosphate is attached. It is now more complex. Complexity increases instability, a consequence of the laws of thermodynamics. Another reason is that the highly charged phosphate creates stress in the molecule due to electrical interactions with other parts of the molecule.

Here's an image (mine) to show the concept of coupled reactions: enter image description here

  • $\begingroup$ Thanks for discussing the role of coupled reaction, i.e. performing a slight unfavorable reaction at 'cost' of highly favorable reaction... that exactly fits to the concept of 'currency', profit and economics. However here the ultimate 'gainer' is nature (entropy working same way as profit of seller) and 'loser' is organism. $\endgroup$ – Always Confused Oct 14 '16 at 2:25
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    $\begingroup$ @AlwaysConfused Thanks! We've come a long way since textbooks likened the energy in ATP as beling like a loaded spring that could somehow do work. $\endgroup$ – bpedit Oct 14 '16 at 2:35
  • $\begingroup$ But still I think a spring analogy is correct; but the 'molecule' ATP is not that spring. rather the 'reaction' ATP <==>ADP +Pi (in appropriate eqlb.) is the spring. A spring too, take energy due to coupling with some other action (hand move), and when it release some energy (do an work); it is too a coupling. $\endgroup$ – Always Confused Oct 14 '16 at 5:32

You seem to have misunderstood energy as some sort of substance which is produced as a product of cellular respiration like CO2 or H2O then released into the bonds of ATP molecules. Remembering that it is not a substance and that it is transferred(and not made) by the breaking and formation of bonds in the process of respiration should help clear that out.

  • $\begingroup$ Do correct me if I'm wrong. $\endgroup$ – MrFregg Oct 13 '16 at 17:48
  • $\begingroup$ it is not that I thought of energy as a substance, I know what energy is not, but I don't know what it is, except that it is the driving force of the universe and that it can take many forms. It is just that I cannot picture it in my mind. Even I consume, store, produce, waste, transform energy and still I can't get it right. $\endgroup$ – aurelius Oct 13 '16 at 18:16
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    $\begingroup$ @aurelius Have a look at this Physics SE question: physics.stackexchange.com/questions/3014/… . $\endgroup$ – MrFregg Oct 14 '16 at 2:17

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