AP BIOLOGY

Detailed explanation-1: -Phosphofructokinase is activated by AMP and fructose-2, 6-bisphosphate and inhibited by ATP, while fructose-1, 6-bisphosphatase is regulated in the opposite manner by the same intermediates. The result is a coordinated control of carbon flux via glycolysis and gluconeogenesis in the liver.

Detailed explanation-2: -In the classic view, F26P2 regulates glucose metabolism by allosteric effects on 6-phosphofructo-1-kinase (6PFK1, activation) and fructose-1, 6-bisphosphatase (FBPase, inhibition). When levels of F26P2 are high, glycolysis is enhanced and gluconeogenesis is inhibited.

Detailed explanation-3: -Fructose-1, 6-Bisphosphatase (FBPase) The enzyme is regulated allosterically by a number of small molecules including AMP and fructose-2, 6-phosphate, which are negative regulators, and ATP that is a positive regulator.

Detailed explanation-4: -Fructose-2, 6-bisphosphate functions as a potent allosteric activator of PFK1, a rate-limiting enzyme of glycolysis. Therefore, TIGAR inhibits glycolysis, thereby redirecting cellular glucose metabolism to the pentose phosphate pathway shunt.

Detailed explanation-5: -While ATP is required to phosphorylate fructose 6-phosphate in glycolysis, none is produced by the dephosphorylation in gluconeogenesis. The enzyme also serves as a key regulatory point, being inhibited by AMP and fructose 2, 6-bisphosphate [3, 4].