Question 1

Which enzyme is used by both glycolysis and gluconeogenesis?

Accepted Answer

Phosphoglycerate kinase

Question 2

What enzyme used in gluconeogenesis reverses the action of the glycolytic enzyme phosphofructokinase-1?

Accepted Answer

Fructose-1,6-bisphosphatase

Question 3

Which of the following statements about gluconeogenesis is false?

Accepted Answer

It consists entirely of the reactions of glycolysis, operating in the reverse direction.

Question 4

Pyruvate cannot be directly converted to phosphoenolpyruvate (PEP) in gluconeogenesis. Which sequence of enzymes is required for this conversion?

Accepted Answer

Pyruvate carboxylase and phosphoenolpyruvate carboxykinase

Question 5

Why is it important that glycolysis and gluconeogenesis are highly regulated and not simultaneously active in the same cell?

Accepted Answer

To prevent futile cycling and waste of energy

Question 6

Which of the following best describes the role of fructose-2,6-bisphosphate in the regulation of glycolysis and gluconeogenesis?

Accepted Answer

It activates phosphofructokinase-1 and inhibits fructose-1,6-bisphosphatase

Question 7

Which of the following equations correctly represents the overall reaction for gluconeogenesis from pyruvate?

Accepted Answer

$$2 \mathrm{Pyruvate} + 4 \mathrm{ATP} + 2 \mathrm{GTP} + 2 \mathrm{NADH} + 6 \mathrm{H_2O} \rightarrow 1 \mathrm{Glucose} + 4 \mathrm{ADP} + 2 \mathrm{GDP} + 6 \mathrm{P_i} + 2 \mathrm{NAD^+} + 2 \mathrm{H^+}$$

Question 8

A patient with a deficiency in glucose-6-phosphatase would most likely present with which of the following symptoms?

Accepted Answer

Inability to maintain blood glucose during fasting

Question 9

Which of the following steps in gluconeogenesis is considered irreversible under physiological conditions?

Accepted Answer

$$\mathrm{Fructose-1,6-bisphosphate} \rightarrow \mathrm{Fructose-6-phosphate}$$

Question 10

Which molecule is an allosteric activator of pyruvate carboxylase in gluconeogenesis?

Accepted Answer

Acetyl-CoA

Question 11

During prolonged fasting, which tissue is primarily responsible for maintaining blood glucose levels via gluconeogenesis?

Accepted Answer

Liver

Question 12

Which of the following best explains why gluconeogenesis is not simply the reverse of glycolysis?

Accepted Answer

Several steps in glycolysis are highly exergonic and must be bypassed by different enzymes in gluconeogenesis

Question 13

Which of the following is a substrate for gluconeogenesis but NOT for glycolysis?

Accepted Answer

Lactate

Question 14

A mutation that causes constitutive activation of phosphofructokinase-1 would most likely result in which metabolic consequence?

Accepted Answer

Increased glycolytic flux and decreased gluconeogenesis

Question 15

Which of the following best describes the fate of oxaloacetate during gluconeogenesis in the cytosol?

Accepted Answer

It is converted to phosphoenolpyruvate by phosphoenolpyruvate carboxykinase

Study Notes: Gluconeogenesis and Glycolysis Regulation

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