<span title="Pyruvate-->oxaloacetate-->malate-->pyruvate">Pyruvate-->oxaloacetate--...</span>

Question

There is a cyclic reaction in which pyruvate becomes oxaloacetate.

The oxaloacetate is converted to malate and then back to pyruvate. This cycle is important because:

a) There is no net use or fixation of CO2 in this cycle.

b) NADH is converted to NADPH in this cycle.

c) There is no net oxidation or reduction in this cycle.

d) NADPH is converted to NADH in this cycle.

e) This is actually a wasteful pathway with no practical use.

Answer 1

This pathway is part of gluconeogenesis - the pyruvate will lead to synthesis of glucose.  See link for a diagram of the pathway.

) There is no net use or fixation of CO2 in this cycle. **CO2 is used to convertpyruvate to oxaloacetate.

b) NADH is converted to NADPH in this cycle. **NADPH not involved

c) There is no net oxidation or reduction in this cycle. ** NADH/NAD is involved in the oxaloacetate --&gt; malate conversion.

d) NADPH is converted to NADH in this cycle. **NADPH is not involved

e) This is actually a wasteful pathway with no practical use.** Used in gluconeogenesis