The concept of ATP -> ADP and energy releasal

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The concept of ATP -> ADP and energy releasal

Post by darks0ulz » Fri Jul 11, 2008 1:14 am

I understand that when:

When bonds form -> energy is released.
When bonds break -> energy is required.

However, from ATP -> ADP (adenine triphosphate -> adenine diphosphate, the removal of one phospide ion), which is a break of the bonds, energy is released.

I don't understand how the breaking down of ATP to ADP releases energy while it should in theory require energy instead.

Already tried looking through the internet/wikipedia and I can't ask my teacher for another 3 days, so I turn to you guys for any suggestions.

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Post by mith » Fri Jul 11, 2008 3:17 pm

Lol, surely, some bonds are forming. Look at the structure of ADP.
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Post by MisterATP » Fri Jul 11, 2008 3:59 pm

I think you aren't right saying that ,,When bonds form -> energy is released.
When bonds break -> energy is required''. You are right in part. Free Gibss energy (G), activation energy of substrates are very important. Allmost every time exergonic and endergonic reactions occurs together. So when ATP is splited released energy help to form bonds. So saying ,,when bonds form -> energy is released''. is right. But as I said, remember whether reaction is endergonic or exergonic is very important. For example, ATP release huge amount of energy, but activation energy is pretty high (actually, activation energy depends on pH and at pH 7 ATP is very stable).

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Post by spirochete » Sun Jul 20, 2008 6:54 am

In most chemical reactions bonds are both broken and formed. Hydrolysis is an example. In hydrolysis the elements of water are added across a bond. ATP is an example of a molecule which has a high free energy of hydrolysis. This doesn't mean that energy is released when any bond in ATP is just broken. You can look up hydrolysis on wikipedia for a full definition.

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