Question

Liver fatty acid synthesis is stimulated by glucose. In which of the following ways does the reaction of glucose not stimulate the synthesis of acyl-CoA in the liver?

a. The reaction of glucose contributes NADPH to the fatty acid synthesis.

b. The turnover of glucose contributes with ATP to fatty acid synthesis.

c. The reaction of glucose contributes with citrate to transport acetyl-CoA to the fatty acid synthesis.

d. The reaction of glucose contributes with acetyl-CoA to the fatty acid synthesis.

e. The reaction of glucose contributes glycerol-3-phosphate to the fatty acid synthesis.

Answer 1

• When glucose concentration increases, for example, after a meal, insulin concentrations rise, glucagon concentrations fall. Glucose is phosphorylated immediately on entry into cells, and thus there is a tight linkage between glucose uptake and glucose metabolism.
• Glucose taken up peripherally can be either stored as muscle glycogen or metabolized via glycolysis to pyruvate. Some of the pyruvate will then be decarboxylated via the pyruvate dehydrogenase enzyme system and enter the tricarboxylic acid cycle as acetyl-CoA for complete oxidation.
• Glucose, along with NADPH converts acetyl CoA to fatty acid either by Pentose Phosphate Shunt or by Glycolysis.
• During the transport, citrate is formed through TCA cycle.

Thus, option (b) is incorrect since glucose turnover number directly doesn't contribute to fatty acid synthesis.