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1.Glucose 6-phosphatase (G6Pase) catalyzes the dephosphorylation of glucose 6-phosphate (G6P). It bypasses the irreversible glycolytic reaction...

1.Glucose 6-phosphatase (G6Pase) catalyzes the dephosphorylation of glucose 6-phosphate (G6P). It bypasses the irreversible glycolytic reaction of glucokinase. Select the best answer that explains why G6Pase does not catalyze the reverse reaction of glucokinase.

A. G6Pase catalyzes an endergonic reaction

B. G6Pase hydrolyzes G6P

C. G6Pase requires energy from ATP to dephosphorylate G6P

D. G6Pase requires only one substrate

5. Insulin and glucagon oppositely control glucose metabolism in the liver. The former is elevated in response to a carbohydrate meal (fed state) and the latter in response to fasting. Show the overall effect of each on the pathways of glucose metabolism.

OPTIONS FOR TABLE: increase or decrease

	Fed state	Fasted state
glucose degradation (glycolysis)
glucose synthesis (gluconeogenesis)
glycogen degradation
glycogen synthesis

Expert Solution

Ans. B G6Pase hydrolysis G6P.

As G6Pase release Glucose on hydrolysis inito blood stream.

G6P is an intermediate substrate in gluconeogenesis.

Also is part of Pentose phosphate pathway.

Ans. 5. Insulin and Glucagon are antagonist.

Insulin promote glycolysis.

Glucagon promotes glycogenolysis, gluconeogenesis, ketolysis.

Circulating glucose is derived from three sources: intestinal absorption during the fed state, glycogenolysis, and gluconeogenesis.

Other sources of circulating glucose are derived chiefly from hepatic processes: glycogenolysis, the breakdown of glycogen, the polymerized storage form of glucose; and gluconeogenesis, the formation of glucose primarily from lactate and amino acids during the fasting state.

Glucagon facilitates this process and thus promotes glucose appearance in the circulation. Over longer periods of fasting, glucose, produced by gluconeogenesis, is released from the liver.

During fed state insulin levels are increased in blood stream to facilitate glucose entry into cells for glycolysis to release ATP.

During fasting period of 5 to 8 hrs glucagon level shoots up to break glycogen stored in muscles and liver to release glucose.

gladiator answered 7 months ago

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