Question

1. Which enzyme is NOT part of the GNG process?

a .Pyruvate kinase

b. Pyruvate carboxylase

c. Phosphoenolpyruvate carboxykinsase

d. Glucose-6-phosphatase

2. Which molecule can NOT be derived from pyruvate in human?

a. Oxaloacetate

b. Acetyl CoA

c. Lactate

d. Ethanol

3. Which one of the following statements regarding the ruminant gluconeogenesis process is correct?

a. It leads to net gain of ATP.

b. It begins with propionate.

c. It begins with lactate.

d. It begins with pyruvate.

Answer 1

1) The enzyme which is not a part of gluconeogenesis is Pyruvate Kinase, Option A. Pyruvate kinase is actually involved in the last energy requiring stage of glycolysis i.e. the break down of Glucose molecules. Having said that it transfers Phophate from Phosphoenolpyruvate to ADP. The Enzymes involved in Gluconeogenesis are:

Phosphoglucoisomerase

Enolase

Phosphoglycerate mutase

Phosphoglycerate kinase

G3P Dehdrogenase

Triosephosphate isomerase

Fructose 1,6 biphosphate aldolase

Pyruvate carboxylase

Phosphoenol pyruvate Carboxykinase

Fructose 1,6 biphosphatase

Glucose 6 phosphatase

2) The correct option is D, Ethanol. Ethanol is derived under Anaerobic conditions but in some microorganisms not in human.

Acetyl coenzyme is derived from Pyruvate under the catalysis of pyruvate dehydrogenase, oxidation of pyruvate. Lactate is formed under anaerobic conditions. And oxaloacetate is derived from pyruvate through Pyruvate carboxylase, all these three derivations occur in humans, animals and microoorganisms except for ethanol conversion in human.

3) The correct option is B, it begins with propionate. Propionate is an importtant precursor of gluconeogensis in ruminant animals (cattle, sheeps, deer etc) because all the dietary carbohydrates have to be fermented to form volatile fatty acids in the rumen(first chamber in the alimentary canal of ruminants also called paunch), and propionate being the only major volatile fatty acid, leads to the commencement of Gluconeogenesis in ruminant animals.