Question 1

All are characteristic of fructose bisphosphate aldolase in animal tissues EXCEPT:

Accepted Answer

Fructose bisphosphate aldolase in animal tissues is a Class I aldolase, not a Class II aldolase.

Question 2

Glucokinase has a K_m value of 10.0 mM, whereas hexokinase has a K_m value of 0.1 mM. This is consistent with which of the following?

Accepted Answer

The lower KM value of hexokinase indicates that it has a higher affinity for glucose compared to glucokinase. This means that hexokinase can effectively phosphorylate glucose even at low glucose concentrations, whereas glucokinase requires higher glucose concentrations to phosphorylate glucose. Thus, option B is the correct answer as glucokinase acts on glucose only at high glucose concentrations.

Question 3

All are characteristics of Type 1 diabetes mellitus EXCEPT:

Accepted Answer

In Type 1 diabetes mellitus, the immune system attacks and destroys the pancreas cells that produce insulin, resulting in insufficient insulin production. This leads to high blood glucose levels and the production of little liver glycogen. Glucokinase is not induced, and there are low levels of it in Type 1 diabetes mellitus. Therefore, the answer is B, as glucokinase is not induced in Type 1 diabetes mellitus.

Question 4

Dihydroxyacetone phosphate is:

Accepted Answer

Dihydroxyacetone phosphate is isomerized to glyceraldehyde-3-phosphate by triose phosphate isomerase (TPI).

Question 5

Adenylate kinase catalyzes the reaction:
ADP + ____ ⇔ ____ + AMP

Accepted Answer

Adenylate kinase catalyzes the conversion of two molecules of ADP into one molecule of ATP and one molecule of AMP, making option C correct.

Question 6

The step that commits glucose to glycolysis is catalyzed by:

Accepted Answer

The step that commits glucose to the glycolytic pathway is the phosphorylation of glucose to glucose-6-phosphate, which is catalyzed by the enzyme hexokinase in most tissues, or by glucokinase in the liver and pancreas. However, the regulation of the glycolytic pathway is mainly carried out by the enzyme phosphofructokinase-1 (PFK-1), which facilitates the conversion of fructose-6-phosphate to fructose-1,6-bisphosphate, the third step of glycolysis. Therefore, the correct answer is C, phosphofructokinase-1 (PFK-1).

Question 7

When phosphoglucoisomerase is secreted by T-cells it:

Accepted Answer

Phosphoglucoisomerase, when secreted by T-cells, acts as a neurotrophic factor promoting the survival of certain spinal neurons and sensory nerves.

Question 8

For phosphofructokinase-1:

Accepted Answer

Low ATP levels indicate a need for energy, stimulating phosphofructokinase-1 to increase glycolysis. Fructose-2,6-bisphosphate is a potent activator of the enzyme, promoting glycolysis even further.

Question 9

All are characteristic of the conversion of glucose to lactate EXCEPT:

Accepted Answer

The conversion of glucose to lactate generates only two ATP per glucose, not four, making option E incorrect. The remaining options are all characteristics of the conversion of glucose to lactate.

Question 10

α-D-Glucose + ATP → ____ + ____ + H⁺

Accepted Answer

The reaction given is a phosphorylation reaction, where glucose is being phosphorylated by ATP. The product formed would be glucose-6-phosphate (G6P) as ATP donates a phosphate group to glucose. Therefore, the correct answer is D - α-D-glucose-6-phosphate and ADP. The other options either involve fructose or a bisphosphate molecule, which is not formed in this reaction.

Question 11

All are important reasons to phosphorylate glucose in the first step of glycolysis EXCEPT:

Accepted Answer

The large positive free energy change is not a reason for phosphorylating glucose in glycolysis. The phosphorylation of glucose by hexokinase (or glucokinase in liver cells) to form glucose-6-phosphate is actually coupled with the hydrolysis of ATP to ADP, which is an energetically favorable reaction. This step is important for trapping glucose within the cell, preventing its transport out, lowering its intracellular concentration to favor further uptake, and providing a means of regulatory control.

Question 12

All are allosteric regulators of phosphofructokinase-1 EXCEPT:

Accepted Answer

The answer of All are allosteric regulators of phosphofructokinase-1 EXCEPT:
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Question 13

All of the following characterize phosphofructokinase-1 (PFK-1) EXCEPT:

Accepted Answer

All of the other choices are true characteristics of PFK-1. However, choice B is false as ATP decreases the affinity of the enzyme for fructose-6-phosphate, not increases it.

Question 14

All are characteristics of the phosphofructokinase-1 catalyzed reaction EXCEPT:

Accepted Answer

All the statements provided are true characteristics of the phosphofructokinase-1 (PFK-1) catalyzed reaction in glycolysis. It is exergonic (releases energy), considered a "priming reaction" because it requires ATP (thus investing energy early in the pathway), acts as a "valve" controlling the rate of glycolysis by being allosterically regulated by various metabolites, and commits the cell to metabolize glucose by catalyzing an irreversible step.

Question 15

Class I aldolases are characterized by:

Accepted Answer

Class I aldolases use a Schiff base intermediate in their reaction mechanism.

Question 16

All are true for the isomerase reaction of glucose-6-phosphate to fructose-6-phosphate EXCEPT:

Accepted Answer

The statement that the reaction is irreversible with a large negative ΔG is false. The isomerase reaction of glucose-6-phosphate to fructose-6-phosphate has a near-equilibrium constant and is reversible. The other statements are true.

Question 17

Which of the following pathways is NOT properly paired with its precursor?

Accepted Answer

Glucosamine-6-phosphate is derived from fructose-6-phosphate through the hexosamine biosynthesis pathway, not from glucose-6-phosphate.

Question 18

All of the following are characteristic of the coupling between glycolysis and the citric acid cycle EXCEPT:

Accepted Answer

Citrate does not directly inhibit glucokinase. Rather, it indirectly inhibits the enzyme by promoting the activity of the kinase that phosphorylates and inactivates glucokinase.

Question 19

For the first five steps of glycolysis, the appropriate sequence of enzymes is:
A.phosphofructokinase-1 (PFK-1).
B.hexokinase / glucokinasE.
C.fructose bisphosphate aldolasE.
D.PhosphoglucoisomerasE.
E.triose phosphate isomerase (TPI).

Accepted Answer

The answer of For the first five steps of glycolysis,...

Question 20

Hexokinase and glucokinase belong to the kinase subclass of what class of enzymes?

Accepted Answer

Hexokinase and glucokinase are both transferases, which catalyze the transfer of a functional group from one molecule to another. Specifically, they transfer a phosphate group from ATP to glucose, which is the first step in glucose metabolism.

Quiz 18: Glycolysis

All are characteristic of fructose bisphosphate aldolase in animal tissues EXCEPT:

Glucokinase has a K_m value of 10.0 mM, whereas hexokinase has a K_m value of 0.1 mM. This is consistent with which of the following?

All are characteristics of Type 1 diabetes mellitus EXCEPT:

Dihydroxyacetone phosphate is:

Adenylate kinase catalyzes the reaction: ADP + ⇔ + AMP

The step that commits glucose to glycolysis is catalyzed by:

When phosphoglucoisomerase is secreted by T-cells it:

For phosphofructokinase-1:

All are characteristic of the conversion of glucose to lactate EXCEPT:

α-D-Glucose + ATP → + + H⁺

All are important reasons to phosphorylate glucose in the first step of glycolysis EXCEPT:

All are allosteric regulators of phosphofructokinase-1 EXCEPT:

All of the following characterize phosphofructokinase-1 (PFK-1) EXCEPT:

All are characteristics of the phosphofructokinase-1 catalyzed reaction EXCEPT:

Class I aldolases are characterized by:

All are true for the isomerase reaction of glucose-6-phosphate to fructose-6-phosphate EXCEPT:

Which of the following pathways is NOT properly paired with its precursor?

All of the following are characteristic of the coupling between glycolysis and the citric acid cycle EXCEPT:

For the first five steps of glycolysis, the appropriate sequence of enzymes is: A.phosphofructokinase-1 (PFK-1) . B.hexokinase / glucokinasE. C.fructose bisphosphate aldolasE. D.PhosphoglucoisomerasE. E.triose phosphate isomerase (TPI) .

Hexokinase and glucokinase belong to the kinase subclass of what class of enzymes?

Quiz 18: Glycolysis

All are characteristic of fructose bisphosphate aldolase in animal tissues EXCEPT:

Glucokinase has a Km value of 10.0 mM, whereas hexokinase has a Km value of 0.1 mM. This is consistent with which of the following?

All are characteristics of Type 1 diabetes mellitus EXCEPT:

Dihydroxyacetone phosphate is:

Adenylate kinase catalyzes the reaction: ADP + ____ ⇔ ____ + AMP

The step that commits glucose to glycolysis is catalyzed by:

When phosphoglucoisomerase is secreted by T-cells it:

For phosphofructokinase-1:

All are characteristic of the conversion of glucose to lactate EXCEPT:

α-D-Glucose + ATP → ____ + ____ + H+

All are important reasons to phosphorylate glucose in the first step of glycolysis EXCEPT:

All are allosteric regulators of phosphofructokinase-1 EXCEPT:

All of the following characterize phosphofructokinase-1 (PFK-1) EXCEPT:

All are characteristics of the phosphofructokinase-1 catalyzed reaction EXCEPT:

Class I aldolases are characterized by:

All are true for the isomerase reaction of glucose-6-phosphate to fructose-6-phosphate EXCEPT:

Which of the following pathways is NOT properly paired with its precursor?

All of the following are characteristic of the coupling between glycolysis and the citric acid cycle EXCEPT:

For the first five steps of glycolysis, the appropriate sequence of enzymes is: A.phosphofructokinase-1 (PFK-1) . B.hexokinase / glucokinasE. C.fructose bisphosphate aldolasE. D.PhosphoglucoisomerasE. E.triose phosphate isomerase (TPI) .

Hexokinase and glucokinase belong to the kinase subclass of what class of enzymes?

Glucokinase has a K_m value of 10.0 mM, whereas hexokinase has a K_m value of 0.1 mM. This is consistent with which of the following?

Adenylate kinase catalyzes the reaction: ADP + ⇔ + AMP

α-D-Glucose + ATP → + + H⁺