$$ \text{Fructose 6-phosphate} + \text{ATP} \rightarrow \text{Fructose 1,6-bisphosphate} + \text{ADP} $$

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

Question 1

Which enzyme catalyzes the committed step of glycolysis, and what is its main regulatory mechanism?

Accepted Answer

Phosphofructokinase-1 (PFK-1); regulated by ATP and AMP levels

Question 2

What effect does high ATP concentration have on phosphofructokinase-1 (PFK-1) activity?

Accepted Answer

It decreases PFK-1 activity by acting as an allosteric inhibitor

Question 3

Which molecule is the most important allosteric activator of PFK-1?

Accepted Answer

AMP

Question 4

Fructose 2,6-bisphosphate has which of the following effects on glycolysis and gluconeogenesis?

Accepted Answer

It stimulates glycolysis and inhibits gluconeogenesis

Question 5

Which enzyme is responsible for the conversion of fructose 1,6-bisphosphate to fructose 6-phosphate in gluconeogenesis?

Accepted Answer

Fructose 1,6-bisphosphatase

Question 6

During fasting, which hormone increases the activity of fructose 2,6-bisphosphatase, thereby promoting gluconeogenesis?

Accepted Answer

Glucagon

Question 7

Which of the following best describes the role of pyruvate kinase in glycolysis?

Accepted Answer

It catalyzes the conversion of phosphoenolpyruvate (PEP) to pyruvate

Question 8

Which equation correctly represents the reaction catalyzed by phosphofructokinase-1 (PFK-1)?

Accepted Answer

$$ 	ext{Fructose 6-phosphate} + 	ext{ATP} ightarrow 	ext{Fructose 1,6-bisphosphate} + 	ext{ADP} $$

Question 9

A patient with a deficiency in fructose 1,6-bisphosphatase would most likely have difficulty with which metabolic process?

Accepted Answer

Gluconeogenesis

Question 10

Which of the following is a direct effect of insulin on glycolysis and gluconeogenesis?

Accepted Answer

Insulin increases glycolysis and decreases gluconeogenesis

Question 11

Which enzyme is activated by fructose 2,6-bisphosphate and is a key regulator of glycolysis?

Accepted Answer

Phosphofructokinase-1 (PFK-1)

Question 12

Which of the following reactions is catalyzed by pyruvate carboxylase in gluconeogenesis?

Accepted Answer

$$ 	ext{Pyruvate} + 	ext{CO}_2 + 	ext{ATP} ightarrow 	ext{Oxaloacetate} + 	ext{ADP} + 	ext{Pi} $$

Question 13

Which of the following best explains why AMP stimulates glycolysis?

Accepted Answer

AMP indicates low energy availability, activating PFK-1 to increase ATP production

Question 14

Which enzyme is inhibited by ATP and citrate, and activated by AMP and fructose 2,6-bisphosphate?

Accepted Answer

Phosphofructokinase-1 (PFK-1)

Question 15

In the context of metabolic regulation, which of the following statements is TRUE regarding the role of glucagon?

Accepted Answer

Glucagon inhibits glycolysis and stimulates gluconeogenesis

Question 16

Which of the following is the correct sequence of intermediates in glycolysis from glucose to pyruvate?

Accepted Answer

Glucose → Fructose 6-phosphate → Fructose 1,6-bisphosphate → Glyceraldehyde 3-phosphate → 3-phosphoglycerate → Phosphoenolpyruvate → Pyruvate

Question 17

Which enzyme is responsible for converting phosphoenolpyruvate (PEP) to pyruvate in glycolysis?

Accepted Answer

Pyruvate kinase

Question 18

A mutation that decreases the activity of phosphofructokinase-2 (PFK-2) would most likely result in which of the following?

Accepted Answer

Decreased levels of fructose 2,6-bisphosphate and reduced glycolysis

Question 19

Which of the following best describes the reciprocal regulation of glycolysis and gluconeogenesis?

Accepted Answer

Glycolysis is activated by insulin, while gluconeogenesis is activated by glucagon

Metabolic Regulation: Glycolysis and Gluconeogenesis

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