Coupled Reactions

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biology_06er
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Coupled Reactions

Post by biology_06er » Tue Aug 22, 2006 10:18 am

Hi there

OK...So I have a test tomorrow eeeeeeek and I am a little confused on something in the lecture notes that doesn't have a very good explanation and I can't find anything similar in the textbook apart from the definition.


so here it goes...a reply would be MOST appreciated

it states that...the energy released (talking about ATP) is used in a wide varirty of processed eg. Muscle contraction, pumping across membranes, biosynthesis etc. In particular it is used in coupling reactions

the underneath it has a box containing the following

C+A <----> B UNFAVOURABLE
A+ATP<---->A-P+ADP FAVOURABLE
A-P+C<---->B+P FAVOURABLE

net effect:
A+C<---->B
ATP<---->Pi+ADP

ie: energy from ATP-->ADP+Pi drives otherwise unfavourable rxn

ok so what does this mean inc. the favourable/unfavourable thing.

From the definition I get that the energy from an exergonic rxn allows an endergonic rxn to occur? is this correct? so what I think it means (PLEASE correct me if I'm wrong) is that C+A<---->B is not an exergonic rxn as it does not involve hydrolysis of a phosphate group hence its unfavourable meaning it does not help an endergonic rxn.

A+ATP<---->A-P+ADP & A-P+C<---->B+P both hydrolyse a Phosphate group=exergonic hence an endergonic rxn can occur-have i explained this correctly...also on my page i have wriiten A-P is a common intermediate but am unsure why I have written this :oops: is there any significance to this? also I am unsure on what the "net effect" means... i would be very grateful for anyhelp/explanation with the above

Thanks
biology_06er

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