Multiple Choice
In glycolysis, ATP is produced directly by which process?
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Review 2: Biosignaling, Glycolysis, Gluconeogenesis, & PP-Pathway
Glycolysis 1
Multiple Choice
Which steps of glycolysis are considered irreversible under physiological conditions?
A
Phosphoglucose isomerase (step 2), aldolase (step 4), and enolase (step 9)
B
Glyceraldehyde-3-phosphate dehydrogenase (step 6) and phosphoglycerate kinase (step 7)
C
Triose phosphate isomerase (step 5), phosphoglycerate mutase (step 8), and lactate dehydrogenase
D
Hexokinase (step 1), phosphofructokinase-1 (step 3), and pyruvate kinase (step 10)
Verified step by step guidance1
Understand that glycolysis consists of a series of enzymatic reactions converting glucose into pyruvate, with some steps being reversible and others irreversible under physiological conditions.
Recall that irreversible steps in metabolic pathways are typically those with large negative changes in Gibbs free energy (\( \Delta G \)) and are tightly regulated.
Identify the enzymes catalyzing irreversible steps in glycolysis: Hexokinase (step 1), which phosphorylates glucose; Phosphofructokinase-1 (step 3), which phosphorylates fructose-6-phosphate; and Pyruvate kinase (step 10), which converts phosphoenolpyruvate to pyruvate.
Note that other steps, such as those catalyzed by phosphoglucose isomerase, aldolase, enolase, glyceraldehyde-3-phosphate dehydrogenase, phosphoglycerate kinase, triose phosphate isomerase, and phosphoglycerate mutase, are reversible under physiological conditions.
Conclude that the irreversible steps serve as key regulatory points in glycolysis, controlling the flux through the pathway and ensuring directionality.
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