Energetic aspects of biological processes

In all organisms the free energy released in redox reactions is conserved in the energy-carrier molecule adenosine triphosphate (ATP) which is the universal carrier 

The inter-relationships between metabolism, energy and redox processes 

The high, negative AC0 values indicate that hydrolysis of the phosphate bond is strongly favoured thermodynamically. 

Another important set of reactions in living systems comprise those that involve redox processes. Reduced pyridine nucleotides, nicotinamide adenine dinucleotide 

All organisms use the same pair of pyridine nucleotides as carrier molecules for hydrogen and electrons. Both of these molecules accept hydrogen and electrons in the redox reactions of catabolism and become reduced. The oxidative half-reactions of catabolism generally produce two H+ and two electrons. The nicotinamide ring can accept two electrons and one H+ and, since the second H+ is released into the solution, most redox reactions in biological systems take the form  

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