1. Driving unfavorable reactions: Coupled reactions allow thermodynamically unfavorable reactions (ΔG > 0) to proceed by coupling them with a favorable reaction (ΔG < 0). This is achieved by having a common intermediate, allowing the energy released from the favorable reaction to be used to power the unfavorable one.
Example: ATP hydrolysis (favorable) drives the synthesis of protein from amino acids (unfavorable) in biological systems.
2. Increased efficiency: By coupling reactions, the overall efficiency of metabolic pathways is increased. This is because the intermediate produced by the first reaction is immediately used by the second reaction, minimizing energy loss and maximizing the conversion of reactants to products.
Example: In glycolysis, the energy released from the oxidation of glucose is used to produce ATP, which is then used to drive other metabolic processes. This coupling ensures efficient energy utilization and prevents energy waste.
