<u>An endergonic reaction is the one which in which energy is consumed. </u>Synthesis of ATP occurs in the inner mitochondrial membrane but it does not happen on its own i.e. this reaction is not spontaneous and therefore this reaction has a positive δg. δg is negative only for those reactions which are spontaneous. <u>The production of ATP from adp and pi (inorganic phosphorus) which is an unfavorable reaction can be made favorable by coupling it with electron transport chain (ETS) which is a favorable reaction.</u> During ETS, H⁺ are pumped from higher concentration to lower concentration with the help of reverse pumps. Since moving molecules/ionic species from higher concentration to lower concentration is a spontaneous process, energy rather than getting consumed gets produced during ETS. This is the reason why δg for pumping H⁺ is negative.
<u>Synthesis of ATP has positive δg but when it is coupled with ETS which has negative δg, the overall δg for ATP synthesis becomes negative. </u>
The entire process of manufacturing energy is known as oxidative phosphorylation, which takes place in the mitochondria, where ATP synthase enzyme is situated in the inner mitochondrial membrane and the F1-component protrudes into the mitochondrial matrix.
In the process, ADP combines with a phosphate to produce ATP. The energy liberated due to the hydrolysis of ATP into ADP is utilized to do cellular function, generally by coupling the exergonic reaction of the hydrolysis of ATP with the endergonic reactions.
The synthesis of ATP from ADP and Pi is an endergonic reaction with positive delta G.
