- Endergonic means absorbing energy
-Bond making is an exothermic process, bd breaking is endothermic

so how come the formation of ATP from ADP and inorganic phosphate is endergonic? we're making bds so shouldn't it be exothermic?

also the answer says the formation of ATP from and inorganic phosphate can drive cellular work...how does the FORMATION do work? isn't it the ATP itself that does work?

bump

when do you look at overall catabolism and anabolism versus if bonds are broken or made?

For my originial question I get now that even though we break bonds (endergonic) to make ADP it's still an exergonic reaction because the whole point of breaking down aTP in the body is to make energy (exergnoic)- think catabolism!

but when do you not think of it as overall and when do you just look at what's going on with the bonds?

related thread: http://forums.studentdoctor.net/showthread.php?t=433537&highlight=endergonic

- Endergonic means absorbing energy
-Bond making is an exothermic process, bd breaking is endothermic

so how come the formation of ATP from ADP and inorganic phosphate is endergonic? we're making bds so shouldn't it be exothermic?

also the answer says the formation of ATP from and inorganic phosphate can drive cellular work...how does the FORMATION do work? isn't it the ATP itself that does work?

Just 1 thought that may help.

Just because a rxn is endergonic, doesn't mean it is necessarily endothermic.

Think G = H-TdeltaS

If G<0, then it is exergonic. However, it can still be an endothermic rxn if S increases enough.

Just want to make sure that is clear...

thanks for pointing that out sacjumpman, but I'm still lost.

I get how making ATP is endergonic and making ADP is exergonic. Yet how come making ATP can drive cellular work? shoudln't only exergonic reactions be able to do that because they're the ones releasing energy?

related problem: topscore test 3 bio#2

The formation of ATP from inorganic phosphate and ADP creates ATP. The hydrolysis of ATP has a -G so it can be coupled to other cellular processes that have +G and make them spontaneous.

i'm sorry i'm not follwing....you're saying hydrolysis of ATP (which makes ADP) is exergonic and therefore can drive cellular work.

the question is saying the opposite- that the formation of ATP (from ADP) drives cellular work.

getting more lost :?

You're looking too much into the question. The choice is driving cellular work because the product from the reaction, ATP, can be used to drive cellular work why hydrolyzed. The reaction doesn't drive cellular work as it is energetically unfavorable. Essentially the question is, "what does ATP do?"