Question

2. The hydrolysis of ATP is the cell’s most commonly used exergonic reaction when performing energy coupling. Explain energy coupling, why it is necessary, and how the hydrolysis of ATP fits into the process. Use vocabulary words such as “endergonic,” “exergonic,” “spontaneous,” and “nonspontaneous.” (8 points)

BIOLOGY CELLULAR RESPIRATION/PHOTOSYNTHESIS

Please answer in one-two paragraphs

Answer 1

Endergonic,

Means when external energy is required to perform any reaction called endergonic reactions.

In which free energy of the product is greater than the reactant hence it is also called as non-spantaneous reaction. and Free energy change ∆G° in the positive sign.

Exergonic,

When the product have less free energy than the reactant then reaction between two reactant evolves energy this is called exergonic and spontaneous reaction, and free energy change ∆G° in the negative sign.

For example;

Formation of Glucose 6 phosphate from glucose and pi( inorganic phosphate) is a very endergonic reactions (non-spantaneous) .

Glucose + Pi ---------------> Glucose 6 phosphate +H2O ∆G° = 13.8 KJ/mol  

But the reaction can be driven in forward direction by coupling it to highly exergonic reaction as-

ATP + H2O -----------------> ADP + Pi ∆G°= -30.5 KJ/mol

Then coupling of reaction-

Glucose + Pi --------------> Glucose 6 phosphate + H2O ∆G° = 13.8 KJ/mol

ATP + H2O -------------------> ADP + Pi ∆G° = -30.5 KJ/mol

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ATP + Glucose ------------------> ADP + Glucose 6 phosphate

( -30. 5) + 13.8 = - 16.2 KJ/mol

Overall free energy changeenergy in negative hence exergonic and spontaneous.

Hence hydrolysis of ATP most commonly used exergonic reaction when performing energy coupling.