Q: Which of the following equations correctly represents the net ATP yield from glycolysis per molecule of glucose under anaerobic conditions?

$$\text{Glucose} + 2 \text{ADP} + 2 \text{P}_i \rightarrow 2 \text{Pyruvate} + 2 \text{ATP} + 2 \text{H}_2\text{O}$$

Question 1

Which of the following best explains why sucrose is not a reducing sugar, while lactose is?

Accepted Answer

Lactose contains a free anomeric carbon, allowing it to act as a reducing sugar, while sucrose's anomeric carbons are both involved in the glycosidic bond.

Question 2

Which of the following statements about the first step of glycolysis is correct?

Accepted Answer

The phosphorylation of glucose by hexokinase traps glucose inside the cell by adding a negative charge.

Question 3

Which enzyme is allosterically inhibited by its product, glucose-6-phosphate?

Accepted Answer

Hexokinase

Question 4

A patient with diabetes has low levels of liver glucokinase. What is the most likely consequence for their blood glucose levels?

Accepted Answer

Blood glucose levels will be higher than normal due to decreased glucose uptake and storage.

Question 5

Which of the following best describes the role of Mg$$^{2+} in $$the phosphoglucoisomerase reaction?

Accepted Answer

Mg$$^{2+}$$ acts as a cofactor to stabilize the negative charges on the phosphate group during isomerization.

Question 6

Which of the following equations correctly represents the net ATP yield from glycolysis per molecule of glucose under anaerobic conditions?

Accepted Answer

$$	ext{Glucose} + 2 	ext{ADP} + 2 	ext{P}_i ightarrow 2 	ext{Pyruvate} + 2 	ext{ATP} + 2 	ext{H}_2	ext{O}$$

Question 7

Which of the following best explains why the isomerization of glucose-6-phosphate to fructose-6-phosphate is necessary in glycolysis?

Accepted Answer

It allows the next phosphorylation to occur at a primary alcohol, making the reaction more efficient.

Question 8

Which of the following statements about hexokinase and glucokinase is correct?

Accepted Answer

Hexokinase is found in most tissues and has a low Km for glucose.

Question 9

Which of the following best describes the fate of pyruvate in yeast under anaerobic conditions?

Accepted Answer

Pyruvate is converted to ethanol and CO$$_2.$$

Question 10

Which of the following is a correct statement about the energy changes in the first step of glycolysis?

Accepted Answer

The overall reaction (ATP hydrolysis coupled to glucose phosphorylation) is exergonic with $$\Delta G$$^{\circ'}$$ = -16.7 kJ/$$mol.

Question 11

Which of the following best explains why glucose-6-phosphate is considered a metabolic hub?

Accepted Answer

It is a precursor for glycogen synthesis, the pentose phosphate pathway, and glycolysis.

Question 12

Which of the following best describes the difference between an α- and β-glycosidic bond?

Accepted Answer

α-glycosidic bonds are formed when the hemiacetal and alcohol are on the same side of their rings, while β-glycosidic bonds are formed when they are on opposite sides.

Question 13

Which of the following is a correct statement about the regulation of glycolysis in the liver?

Accepted Answer

Glucokinase is synthesized in response to high dietary glucose and insulin.

Question 14

Which of the following best explains how glucose is kept inside the cell against a concentration gradient?

Accepted Answer

Glucose is kept inside the cell by conversion to glucose-6-phosphate, which cannot cross the membrane due to its negative charge.

Question 15

Which carbons of the original glucose are phosphorylated in the two molecules of glyceraldehyde 3-phosphate produced during glycolysis?

Accepted Answer

C-1 and C-6

Question 16

Which of the following is a correct description of the mechanism of phosphoglucoisomerase?

Accepted Answer

It involves ring opening, formation of an enediol intermediate, and ring closure.

Question 17

Which of the following is a correct statement about the fate of pyruvate in muscle cells under anaerobic conditions?

Accepted Answer

Pyruvate is converted to lactate.

Question 18

Which of the following best describes the function of glycoconjugates in cells?

Accepted Answer

They are involved in cell signaling, recognition, and structural roles.

LEC 17 Oligosaccharides, Polysaccharides, Glycoconjugates, and Glycolysis: Structure, Function, and Metabolic Pathways

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