Question 1

Which of the following is NOT a major precursor for gluconeogenesis in humans?

Accepted Answer

Fatty acids

Question 2

During a prolonged fast, which organ contributes up to 40% of total gluconeogenesis?

Accepted Answer

Kidney

Question 3

Which enzyme catalyzes the conversion of pyruvate to oxaloacetate in gluconeogenesis?

Accepted Answer

Pyruvate carboxylase

Question 4

What coenzyme is required by pyruvate carboxylase for its activity?

Accepted Answer

Biotin

Question 5

Which reaction in gluconeogenesis bypasses the irreversible phosphofructokinase-1 (PFK-1) step of glycolysis?

Accepted Answer

Hydrolysis of fructose 1,6-bisphosphate by fructose 1,6-bisphosphatase

Question 6

Which molecule allosterically activates pyruvate carboxylase?

Accepted Answer

Acetyl CoA

Question 7

In the Cori cycle, what is the fate of lactate produced by exercising muscle?

Accepted Answer

It is converted to glucose in the liver

Question 8

Which of the following steps in gluconeogenesis requires GTP hydrolysis?

Accepted Answer

Conversion of oxaloacetate to phosphoenolpyruvate by PEPCK

Question 9

Which of the following inhibits fructose 1,6-bisphosphatase?

Accepted Answer

Fructose 2,6-bisphosphate

Question 10

A patient with a deficiency in glucose 6-phosphatase would most likely present with which clinical symptom during fasting?

Accepted Answer

Fasting hypoglycemia

Question 11

Which of the following equations correctly represents the reaction catalyzed by pyruvate carboxylase?

Accepted Answer

$$\mathrm{Pyruvate} + \mathrm{CO}_2 + \mathrm{ATP} \rightarrow \mathrm{Oxaloacetate} + \mathrm{ADP} + \mathrm{Pi}$$

Question 12

Which enzyme is responsible for the final step in gluconeogenesis, releasing free glucose into the bloodstream?

Accepted Answer

Glucose 6-phosphatase

Question 13

Which of the following statements about the regulation of gluconeogenesis is TRUE?

Accepted Answer

Acetyl CoA activates pyruvate carboxylase

Question 14

Which of the following is a correct multi-step sequence for the conversion of pyruvate to phosphoenolpyruvate (PEP) in gluconeogenesis?

Accepted Answer

Pyruvate $$\rightarrow$$ Oxaloacetate $$\rightarrow$$ Malate $$\rightarrow$$ Oxaloacetate $$\rightarrow$$ PEP

Question 15

Which hormone increases the transcription of the gene for phosphoenolpyruvate carboxykinase (PEPCK) during fasting?

Accepted Answer

Glucagon

Question 16

Which of the following best explains why fatty acids cannot be used as substrates for gluconeogenesis?

Accepted Answer

Fatty acid oxidation produces acetyl CoA, which cannot be converted to pyruvate or oxaloacetate in humans

Question 17

Which of the following is a direct product of the reaction catalyzed by phosphoenolpyruvate carboxykinase (PEPCK)?

Accepted Answer

Phosphoenolpyruvate (PEP)

Question 18

Which of the following best describes the role of NADH in gluconeogenesis?

Accepted Answer

It is required for the reduction of 1,3-bisphosphoglycerate to glyceraldehyde 3-phosphate

Question 19

Which of the following is a consequence of increased acetyl CoA levels in the liver during fasting?

Accepted Answer

Activation of pyruvate carboxylase and increased gluconeogenesis

Gluconeogenesis: Pathway, Substrates, and Regulation

Guida di studio - Domande di pratica