Question

standard free energy change alone cannot predict the direction of biochemical reaction comment​

Answer 1

Answer:

Biochemical processes in the body occur spontaneously in a certain direction, ensuring their normal functioning. Changes in the enthalpy or internal energy of the system occurring in accordance with the first law of thermodynamics allow us to quantitatively determine the thermal effect of the reaction, the conversion of various forms of energy, the exchange parameters of biochemical systems of matter and energy with the environment, but these thermodynamic functions cannot serve as criteria determining the direction of reactions, the possibility of their spontaneous implementation. They also do not allow us to estimate how much energy a biochemical system must receive in order to initiate spontaneous transformation in it. It should also be noted that, in bioenergy systems, the change in free energy, as a rule, is not equal to zero, which is observed upon the occurrence of thermodynamic equilibrium. Therefore, biochemical systems in the course of transformations of substances almost never reach true chemical equilibrium. They are characterized by the so-called stationary states, when certain rates of the influx of substances and energy into the system and their outflow from the system are maintained, since the products formed during the reaction do not accumulate, but undergo further transformations. When a stationary state is reached, maximum rates of biochemical transformations are provided, which are also accompanied by a significant decrease or increase in free energy.