When ATP is converted to ADP one bond is broken and a phosphate group is liberated. But shouldn't energy be put in to the molecule to break a bond? If that's the case, how does breaking the phosphate bond allow ATP to give energy to other molecules?

It takes energy to break the bond but as the bond breaks it releases energy. More energy is released as the bond breaks than it takes to break the bond, and this energy is available to other molecules.

why is energy liberated when the bond is broken?

umm, skye are you sure?

 

breaking bonds typically uses up energy and forming bonds releases energy. this is because the bound stat is at a lower energy level than the unbound state.

From what i have learned: stuffing a third phosphate to ADP has a negative ΔG. Anabolic processes reverse that reaction so that results in a positive ΔG, therefore it produces energy.

umm, skye are you sure?

 

breaking bonds typically uses up energy and forming bonds releases energy. this is because the bound stat is at a lower energy level than the unbound state.

Yeah it was a poor answer by me.

 

It depends how you view the reaction. Often, like Fuzzwood says, it's considered to a positive change in free energy in water, since energy is released. But really this energy comes from the better stability of the ADP molecule in water, with the formation of hydration bonds.

Yeah it was a poor answer by me.

 

It depends how you view the reaction. Often, like Fuzzwood says, it's considered to a positive change in free energy in water, since energy is released. But really this energy comes from the better stability of the ADP molecule in water, with the formation of hydration bonds.

It is due to the levels of ATP compare to ADP and AMP being keeps so far from equilibrium, this is the reason it works as an effective energy store.

umm, skye are you sure?

 

breaking bonds typically uses up energy and forming bonds releases energy. this is because the bound stat is at a lower energy level than the unbound state.

 

Chemical reactions that include breaking bonds can be exothermic or endothermic. You have to consider the total energy of your reactants vs. your products.

 

Here you can see the process of a chemical reaction. (Try to ignore all the letters and arrows and concentrate on the black path.) The graph shows energy levels as a function of time. Read from left to right you'll notice that to start the reaction a lot of energy is needed, and some of that energy is then contained in the resulting product. This is equivalent to the production of ATP.

 

When ATP->ADP this happens backwards. Some energy is needed to get over the 'energy barrier', known as the activation energy, of the reaction, after which a considerable amount of energy is released (more than was needed to activate the reaction).

 

Thus energy is needed, but also released, in the process of ATP->ADP.