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Homework Help: ATP in Muscle Contractions

  1. Feb 4, 2006 #1
    >> Calculate approximately how many molecules of ATP are required for a standard muscle like the biceps during the contraction phase of a single twitch.

    I honestly do not even know where to begin here... I don't think he wants us to go through and just outline Glycolysis/Kreb's Cycle/ETC because that's just producing ATP in general, not for a specific contraction. And that's not saying how much is NEEDED...

    I've looked around on the internet but can't really seem to come up with an answer. I know that calcium is needed but again, I can't figure out how much.

    Does anyone think they could help me out? Thanks
  2. jcsd
  3. Aug 14, 2017 #2


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    There are tons of different ways to approach this problem, from the very simple to the very involved. I'll go a very simple way. Let's take the bicep, for instance. Let's say you lift a 10kg weight 0.5m directly upward (using only your bicep somehow). This requires your bicep to do:
    $$W = mgh = (10kg)(9.8m/s^2)(0.5m) = 49J$$
    worth of work. ATP hydrolysis releases 30.5 kJ mol-1. This means that the number of moles of ATP required to do 49 J worth of work is:
    $$\frac{49J}{30500J\cdot mol^{-1}}=1.6\times 10^{-3} mol$$
    To get number of molecules, simply multiply by Avogadro's number:
    $$(1.6\times 10^{-3} mol)(6.022 \times 10^{23} mol^{-1}) = 9.6 \times 10^{20}$$
    So an order of magnitude estimate would be roughly 1021 molecules of ATP per muscle contraction.
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