Q: Which of the following is a correct net equation for glycolysis in the conversion of glucose to pyruvate?

$$\text{Glucose} + 2 \text{ADP} + 2 \text{P}_i + 2 \text{NAD}^+ \rightarrow 2 \text{Pyruvate} + 2 \text{ATP} + 2 \text{NADH} + 2 \text{H}^+$$

Q: Which of the following is the correct stoichiometry for gluconeogenesis from pyruvate?

$$2\text{Pyruvate} + 4\text{ATP} + 2\text{GTP} + 2\text{NADH} + 6\text{H}_2\text{O} \rightarrow \text{Glucose} + 4\text{ADP} + 2\text{GDP} + 6\text{P}_i + 2\text{NAD}^+ + 2\text{H}^+$$

Question 1

During a 200-meter sprint, such as Usain Bolt's Olympic run, which metabolic pathway is primarily responsible for ATP generation in muscle cells when oxygen delivery cannot meet demand?

Accepted Answer

Glycolysis followed by lactic acid fermentation

Question 2

Which of the following statements best explains why the regeneration of NAD$$^+ is $$crucial for glycolysis to continue under anaerobic conditions?

Accepted Answer

NAD$$^+ is $$needed for the oxidation of glyceraldehyde 3-phosphate to 1,3-bisphosphoglycerate.

Question 3

Which enzyme catalyzes the first irreversible step of glycolysis, and what is the product of this reaction?

Accepted Answer

Phosphofructokinase; fructose 1,6-bisphosphate

Question 4

Which of the following is a correct net equation for glycolysis in the conversion of glucose to pyruvate?

Accepted Answer

$$	ext{Glucose} + 2 	ext{ADP} + 2 	ext{P}_i + 2 	ext{NAD}^+ ightarrow 2 	ext{Pyruvate} + 2 	ext{ATP} + 2 	ext{NADH} + 2 	ext{H}^+$$

Question 5

A patient with a deficiency in triose phosphate isomerase would most likely experience which of the following consequences?

Accepted Answer

Accumulation of dihydroxyacetone phosphate and impaired ATP production

Question 6

Which of the following best describes the role of substrate channeling in glycolytic enzyme complexes within eukaryotic cells?

Accepted Answer

It allows for the direct transfer of intermediates between enzymes, increasing efficiency and preventing release of toxic intermediates.

Question 7

Which of the following regulatory molecules acts as a powerful activator of phosphofructokinase in the liver?

Accepted Answer

Fructose 2,6-bisphosphate

Question 8

In the context of gluconeogenesis, which enzyme catalyzes the irreversible hydrolysis of fructose 1,6-bisphosphate to fructose 6-phosphate?

Accepted Answer

Fructose 1,6-bisphosphatase

Question 9

Which of the following best explains why excessive fructose consumption can lead to fatty liver and insulin resistance?

Accepted Answer

Fructose metabolism in the liver bypasses phosphofructokinase, leading to excess pyruvate and acetyl CoA, which are converted to fatty acids.

Question 10

Which of the following is the correct stoichiometry for gluconeogenesis from pyruvate?

Accepted Answer

$$2	ext{Pyruvate} + 4	ext{ATP} + 2	ext{GTP} + 2	ext{NADH} + 6	ext{H}_2	ext{O} ightarrow 	ext{Glucose} + 4	ext{ADP} + 2	ext{GDP} + 6	ext{P}_i + 2	ext{NAD}^+ + 2	ext{H}^+$$

Question 11

Which of the following best describes the Cori cycle?

Accepted Answer

It is the process by which lactate produced by muscle during anaerobic glycolysis is transported to the liver and converted back to glucose.

Question 12

Which of the following enzymes requires biotin as a cofactor and is involved in the first step of gluconeogenesis from pyruvate?

Accepted Answer

Pyruvate carboxylase

Question 13

Which glucose transporter is primarily responsible for removing excess glucose from the blood in the liver and has a high $$K_m$$ value?

Accepted Answer

GLUT2

Question 14

Which of the following best explains the Warburg effect observed in rapidly growing tumor cells?

Accepted Answer

Tumor cells preferentially metabolize glucose to lactate via glycolysis even in the presence of oxygen.

Question 15

Which of the following is a key regulatory difference between glycolysis in muscle and liver?

Accepted Answer

In the liver, phosphofructokinase is activated by fructose 2,6-bisphosphate, while in muscle it is regulated primarily by ATP and AMP.

Question 16

Which of the following best describes the reciprocal regulation of glycolysis and gluconeogenesis at the interconversion of fructose 1,6-bisphosphate and fructose 6-phosphate?

Accepted Answer

Fructose 2,6-bisphosphate stimulates phosphofructokinase and inhibits fructose 1,6-bisphosphatase.

Question 17

A patient presents with cataracts and liver enlargement. Laboratory tests reveal a deficiency in galactose 1-phosphate uridyl transferase. What is the most likely diagnosis?

Accepted Answer

Classic galactosemia

Question 18

Which of the following reactions is catalyzed by glyceraldehyde 3-phosphate dehydrogenase in glycolysis?

Accepted Answer

$$	ext{Glyceraldehyde 3-phosphate} + 	ext{NAD}^+ + 	ext{P}_i ightarrow 1,3	ext{-bisphosphoglycerate} + 	ext{NADH} + 	ext{H}^+$$

Glycolysis & Gluconeogenesis: Chapter 16 Study Notes

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