Question

e. How many ATP can be generated if lactose is completely breakdown? Don't forget to account for ATP is used in activating the component of lactose before entering the glycolysis pathway. Assuming malate-asparate shuttle is used to transfer reducing equivalents into the mitochondria. Show your work!

Answer 1

The malate-aspartate shuttle system, is an essential system used by mitochondria, that allows electrons to move across the impermeable membrane between the cytosol and the mitochondrial matrix. The electrons are created during glycolysis which are needed for oxidative phosphorylation.

the malate-aspartate shuttle regenerates NADH inside the mitochondrial matrix, it is capable of maximizing the number of ATPs produced in glycolysis, ultimately resulting in a net gain of 38 ATP molecules per molecule of glucose metabolized.

Glycolysis = 2 ATP

NADH transport cost   = -2 ATP

Pyruvate into Acetyl CoA= 0 ATP

Kreb Cycle = 2 ATP

ETC = 34 ATP       

Total= 36 + 2 From Shuttle = 38 per glucose.

So Glucose + Galactose = 38*2= 76 ATP.