AP BIOLOGY

Detailed explanation-1: -¶ Pyruvate is converted to phosphoenolpyruvate (PEP) in a two-step process via oxaloacetate (OA), which can be viewed as an “activated” form of pyruvate. Bicarbonate and the cofactor biotin are involved in this activation, which requires the expenditure of ATP.

Detailed explanation-2: -PPDK catalyses the conversion of pyruvate to phosphoenolpyruvate (PEP), consuming 1 molecule of ATP, and producing one molecule of AMP in the process. The mechanism consists of 3 reversible reactions: The enzyme PPDK binds to ATP, to produce AMP and a diphosphorylated PPDK.

Detailed explanation-3: -The transition reaction is a one-way reaction, meaning that acetyl-CoA cannot be converted back to pyruvate.

Detailed explanation-4: -Oxaloacetate is then converted to phosphoenolpyruvate. The next several steps are a reversal of glycolytic enzymes and result in the conversion of phosphoenolpyruvate to dihydroxyacetone phosphate and glyceraldehyde 3-phosphate, which then condense to form fructose 1, 6-bisphosphate.