endergonic/exergonic vs. endothermic/exothermic

rav4182 · May 16, 2011

someone plz explain the difference to me. other forums about this have been confusing

on topscore 3 it said hydrolysis of atp is endergonic. i dont understand why. it releases energy so i know its exothermic, but how is it endergonic???

Juggernauts · May 16, 2011

Breaking a bond requires an energy imput. It's like the difference between gross income and net income. Or gross ATP from net ATP of glycolosis(just using this as an example.) the act of splitting the bonds of glucose requires 2atp of energy imput(endergonic) but your going to produce 4 ATP(exothermic reaction). There is probably a better explanation out there but that's the way I look at gonic vs thermic definitions.

tRad · May 16, 2011

rav4182 said:
someone plz explain the difference to me. other forums about this have been confusing

on topscore 3 it said hydrolysis of atp is endergonic. i dont understand why. it releases energy so i know its exothermic, but how is it endergonic???

The release of energy in the form of heat is exothermic while the input of energy in the form of work is endergonic. Or, the absorption of energy in the form of heat is endothermic while the release of energy in the form of work is exergonic. To break bonds you need to input energy in the form of work, just as Juggernauts explained.

rav4182 · May 16, 2011

I just looked at dat destroyer 2010 question 363 BIO section

it says hydrolysis of atp is exergonic! for the explanation it says

"an an endergonic reaction is any nonspontaneous reaction and has a +deltaG. a an exergonic reaction has a -deltaG. hydrolysis of atp yields a deltaG of -30.5 KJ/Mol. the free energy is used to drive reactions that are endergonic to completeion"

WTF is topscore 3 wrong? i dont know what to beleive anymore. it seems like it should be something easy.

tRad · May 16, 2011

I agree, I think destroyer is correct. I dont think topscore went into as much detail as destroyer did. In general breaking bonds is endergonic but in the case of ATP hydrolysis its exergonic since ADP has less energy then ATP.

rav4182 · May 16, 2011

so i guess topscore was wrong and my initial instincts were right

Sanatore · Feb 19, 2013

Correct, ATP formation is endergonic, because the ATP molecule has a high density of negative charges.

ATP hydrolysis is exergonic.

However, note that the energy used to fuel our cells isn't directly provided by ATP, but that when ATP is hydrolyzed, it forms complexes with other molecules whose hydrolysis gives the cells energy.

biomolecmed · Feb 19, 2013

It is a typo. They meant to say exergonic. The dehydration synthesis of ATP is endergonic.

endergonic/exergonic vs. endothermic/exothermic

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