Glycolysis, gluconeogenesis, and glycogen metabolism pathways tested on USMLE Step 1.
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- What is the rate-limiting enzyme of glycolysis?
- Phosphofructokinase-1 (PFK-1)
- What reaction does PFK-1 catalyze?
- Fructose-6-phosphate to fructose-1,6-bisphosphate
- Name a major allosteric activator of PFK-1.
- AMP
- What two molecules allosterically inhibit PFK-1?
- ATP and citrate
- What is the net ATP yield from one glucose molecule in glycolysis?
- 2 ATP (net, via substrate-level phosphorylation)
- How do hexokinase and glucokinase differ in substrate affinity?
- Hexokinase has a low Km (high affinity for glucose); glucokinase has a high Km (low affinity)
- In which tissues is glucokinase primarily found?
- Liver and pancreatic beta cells
- What hormone induces increased glucokinase gene expression in the liver?
- Insulin
- What inhibits hexokinase activity?
- Its own product, glucose-6-phosphate
- A deficiency of which glycolytic enzyme causes hereditary hemolytic anemia?
- Pyruvate kinase
- What reaction does pyruvate kinase catalyze?
- Phosphoenolpyruvate to pyruvate, generating ATP
- Which glycolytic enzyme is inhibited by arsenic poisoning?
- Glyceraldehyde-3-phosphate dehydrogenase (GAPDH)
- What is the rate-limiting enzyme of gluconeogenesis?
- Fructose-1,6-bisphosphatase
- What reaction does pyruvate carboxylase catalyze?
- Pyruvate to oxaloacetate
- What vitamin-derived cofactor does pyruvate carboxylase require?
- Biotin