PPT Slide

Example of Coupling in Reactions

Compound A + ADP +Pi __ Compound B + ATP + Heat

• Compound A gives up its energy to synthesize ATP. Enough of the free energy is captured by the rxn to accomplish this task (free energy is that available to perform work).

• Heat escapes because the efficiency of energy capture is not 100%

• Compound B now has less energy stored in it than Compound A had.

• The energy that is released by the high energy compound A is referred to as free energy (_G), or that which is capable of performing work.

In order for a molecule to be able to resynthesize ATP, it must possess a greater _G than ATP itself (>7 Kcal/mol)

Energy transfer can only be accomplished ìdownhillî

Example:

Creatine Phosphate (_G = 10-12 Kcal/mol)

CP + ADP __ ATP

Rxn is feasible as _G for CP degradation >> that for ATP synthesis

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