What happens to all that energy? _____ How come respiration from glucose (or any

Question

What happens to all that energy? _____ How come respiration from glucose (or any pathway) is accomplished in many small steps instead of just one big reaction? _____ Should the Delta G degree for the entire reaction change if it is done in many little steps rather in one big step? ______ In the body, the first step of glycolysis, where glucose needs to be converted into glucose-6-P, should actually be an "endergonic" reaction. Yet the enzyme hexokinase knows how to "couple" two reactions together to get what should be endergonic reaction to take place. Explain this coupling process.

Explanation / Answer

PART 1 ANSWER

The standard free energy change, can be calculated by substituting standard enthalpies and entropies of reaction and a Kelvin temperature into the Gibbs equation.
The Gibbs free energy (G) of a system is a measure of the amount of usable energy (energy that can do work) in that system.
G= Gfinal - G initial
=H - T * S
H is the enthalpy change.
S is the entropy change.
So if through on one large glucose breakdown happens then the entrophy becomes Positive meaning the symtem is more disordered, so to reduce the make the system entrophy in stable conditions small reactions takes palce for glucose breakdown.

PART 2 ANSWER

Yes G will change, we need to look at if the one step big reaction is energonic or exargonic based on that G will change.

PART 3 ANSWER

Hexokinase undergoes and induced-fit conformational change while binding to glucose, which ultimately prevents the hydrolysis of ATP. It is also allosterically inhibited by physiological concentrations of its immediate product, glucose-6-phosphate. This is a mechanism by which the influx of substrate into the glycolytic pathway is controlled. Hexokinase has regulatory as well as catalytic roles, So the G will be increased/get positive value to make it an endergonic reaction, this is how hexokinase controls two reaction together and an endergonic reaction takes place.

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