Question

For each of the following redox reactions (not balanced), define which component is being reduced and which is being oxidized as the reaction progresses. *It may be quite beneficial to draw the element in question and its electrons in its reactant and product state. 1) C6H12O6 + O2 → CO2 + H2O Carbon is Oxygen is 2) CO2 + H2O + CHA + O2 Carbon is Oxygen is 3) NAD + H+ + 2e + Malate → NADH + Oxaloacetate NAD is Malate is into Oxaloacetate *Note Malate and Oxaloacetate are citric acid cycle intermediates. Determine the fate of NAD+ which should allow you to determine the fate of this reaction.

Answer 1

1) this equation is not balanced, the number of carbon atoms in the glucose is 6, but in the products, there is only one carbon atom.

the balanced equation is

C₆H₁₂O₆ + O₂ $\rightarrow$ 6CO₂+ 6H₂O

now the number of atoms is balanced on both sides.

here glucose is oxidized ( oxidation is the removal of Hydrogen atoms) to carbon dioxide and oxygen is reduced to water.

2) this equation is balanced. the number of atoms are equal on both sides.

Carbon dioxide is converted to methane, carbon is reduced and water is oxidized to oxygen ( the hydron atoms in the water are removed)

3) this equation is also balanced. electrons and hydrogen atoms are added to NAD+ and electrons and H+ from the malate is removed so.

NAD + is reduced to NADH, and malate is oxidized to oxaloacetate