A 45-year-old male presents to the Emergency Room with hematemesis and melena, which is actively managed. He has been previously diagnosed with liver cirrhosis. An esophago-gastro- duodenoscopy has been planned and patient has been asked to observe an overnight fast in esophagogastroduodenoscopy preparation of endoscopy. Patient had dinner at 7 pm and endoscopy was performed at 1 pm the next day. At the time of endoscopy, some pathways were generating glucose to maintain serum glucose levels. Which of the following enzymes catalyze the irreversible biochemical reaction of this process?

Answer: c) Fructose-1,6-bisphosphatase* Patient is observing a fast for 18 hours.* During fasting, glycogen storage is usually depleted within 12 hours.* After this point, gluconeogenesis is mainly responsible for maintaining serum glucose levels by converting non-glucose substances to glucose.* It occurs within liver and is opposite of glycolysis with four key irreversible steps.* One of those steps is conversion of Fructose 1,6-bisphosphate to Fructose-6-phosphate.* It is catalyzed by the enzyme, Fructose-1,6-bisphosphatase.* The other irreversible steps are:o The conversion of Pyruvate to Oxaloacetate, catalyzed by Pyruvate carboxylase enzyme and requires biotin.o The conversion of Oxaloacetate to Phosphoenolpyruvate, catalyzed by Phosphoenolpyruvate carboxykinase.o The conversion of Glucose-6-phosphate to Glucose, catalyzed by Glucose 6-phosphatase.