Write balanced equations for all the reactions in the catabolism of glucose to two molecules of glyceraldehyde 3-phosphate (the preparatory phase of glycolysis), including the standard free-energy change for each reaction. Then write the overall or net equation for the preparatory phase of glycolysis, with the net standard free-energy change.

Solution :

The balanced chemical equation are

The Catabolism of the glucose takes place in five stages :

1. Glucose + → glucose - - phosphate  ,  

2. Glucose - - phosphate → Fructose - - phosphate ,  

3. Glucose - - phosphate + → + Fructose - ,  

4. Fructose -  → dihydroxyacetonephosphate + glyceraldehyde   phosphate,  

5. Dihydroxyacetonephosphate → glyceraldehyde   phosphate ,

Therefore, the overall net equations

Glucose + glyceraldehyde   phosphate +