Question 1

Which of the following statements regarding sugar metabolism is correct?

Accepted Answer

A) Lactase,a b-galactosidase-type enzyme,cleaves the a(1,4)glycosidic bond observed in lactose. 
B) In the liver,fructose is converted to fructose-1-P,then to DHAP and glyceraldehyde,thus skipping normal glycolytic regulation. 
C) In the muscle,fructose is converted into fructose-1-P by hexokinase. 
D) Galactose enters glycolysis as galactose-6-P. 
A) Lactase,a b-galactosidase-type enzyme,cleaves the a(1,4)glycosidic bond observed in lactose. 
B) In the liver,fructose is converted to fructose-1-P,then to DHAP and glyceraldehyde,thus skipping normal glycolytic regulation. 
C) In the muscle,fructose is converted into fructose-1-P by hexokinase. 
D) Galactose enters glycolysis as galactose-6-P.

Question 2

Which enzyme is NOT involved in the first 5 steps of glycolysis?

Accepted Answer

A) phosphofructokinase-1 (PFK-1) 
B) phosphoglycerate kinase 
C) fructose bisphosphate aldolase 
D) triose phosphate isomerase (TPI) 
A) phosphofructokinase-1 (PFK-1) 
B) phosphoglycerate kinase 
C) fructose bisphosphate aldolase 
D) triose phosphate isomerase (TPI)

Question 3

Which of the following stable tautomers of pyruvate is formed during the conversion of PEP to pyruvate?

Accepted Answer

A) enol 
B) keto 
C) imine 
D) aldol 
A) enol 
B) keto 
C) imine 
D) aldol

Question 4

How is phosphofructokinase-1 regulated?

Accepted Answer

A) Low ATP stimulates the enzyme,but fructose-2,6-bisphosphate inhibits. 
B) High ATP stimulates the enzyme,and fructose-2,6-bisphosphate activates. 
C) High ATP stimulates the enzyme,but fructose-2,6-bisphosphate inhibits. 
D) Low ATP stimulates the enzyme,and fructose-2,6-bisphosphate activates. 
A) Low ATP stimulates the enzyme,but fructose-2,6-bisphosphate inhibits. 
B) High ATP stimulates the enzyme,and fructose-2,6-bisphosphate activates. 
C) High ATP stimulates the enzyme,but fructose-2,6-bisphosphate inhibits. 
D) Low ATP stimulates the enzyme,and fructose-2,6-bisphosphate activates.

Question 5

Which of the following is an allosteric effector of pyruvate kinase?

Accepted Answer

A) acetyl-CoA 
B) pyruvate 
C) citrate 
D) PFK-1 
A) acetyl-CoA 
B) pyruvate 
C) citrate 
D) PFK-1

Question 6

If glucose were labelled with ¹⁴C at carbon #6,which carbon of pyruvate would have the ¹⁴C?

Accepted Answer

A) carboxyl carbon 
B) ketone carbon 
C) methyl carbon 
D) The 14C would be lost as CO₂. 
A) carboxyl carbon 
B) ketone carbon 
C) methyl carbon 
D) The 14C would be lost as CO₂.

Question 7

Which of the following characterizes the conversion of glucose to lactate?

Accepted Answer

A) aerobic pathway with no net oxidation 
B) "primed" by ATP phosphorylation 
C) located in the mitochondria 
D) net production of 4 ATP per glucose 
A) aerobic pathway with no net oxidation 
B) "primed" by ATP phosphorylation 
C) located in the mitochondria 
D) net production of 4 ATP per glucose

Question 8

Which of the following is NOT a characteristic of the phosphofructokinase-1 catalyzed reaction?

Accepted Answer

A) endergonic 
B) "priming reaction" 
C) "valve" controlling the rate of glycolysis 
D) commits the cell to metabolize glucose 
A) endergonic 
B) "priming reaction" 
C) "valve" controlling the rate of glycolysis 
D) commits the cell to metabolize glucose

Question 9

Which of the following two proteins form the dimeric complex lactose synthase?

Accepted Answer

A) lactase and ?-galactosidase 
B) galactosyl transferase and lactase 
C) a-lactalbumin and galactosyl transferase 
D) galactosyl transferase and ?-galactosidase 
A) lactase and ?-galactosidase 
B) galactosyl transferase and lactase 
C) a-lactalbumin and galactosyl transferase 
D) galactosyl transferase and ?-galactosidase

Question 10

Which of the following enzymes is NOT used when fructose is metabolized to pyruvate in the liver?

Accepted Answer

A) triose phosphate isomerase 
B) glyceraldehyde-3-phosphate dehydrogenase 
C) glucokinase 
D) phosphofructokinase-1 
A) triose phosphate isomerase 
B) glyceraldehyde-3-phosphate dehydrogenase 
C) glucokinase 
D) phosphofructokinase-1

Question 11

Which of the following enzymes in the liver is used to phosphorylate fructose to fructose-1-phosphate?

Accepted Answer

A) glucokinase 
B) phosphofructokinase-1 
C) hexokinase 
D) fructokinase 
A) glucokinase 
B) phosphofructokinase-1 
C) hexokinase 
D) fructokinase

Question 12

Which of the following enzymes catalyzes substrate-level phosphorylation during glycolysis?

Accepted Answer

A) phosphoglycerate kinase 
B) hexokinase 
C) phosphofructokinase 
D) glucokinase 
A) phosphoglycerate kinase 
B) hexokinase 
C) phosphofructokinase 
D) glucokinase

Question 13

Which of the following enzymes catalyzes the reaction 1,3-bisphosphoglycerate ? 2,3-bisphosphoglycerate?
-Which of the following enzymes catalyzes the reaction 1,3-bisphosphoglycerate ? 2,3-bisphosphoglycerate?

Accepted Answer

A) bisphosphoglycerate phosphatase 
B) bisphosphoglycerate mutase 
C) 2,3-bisphosphoglycerate synthetase 
D) 1,3-bisphosphoglycerate hydrolase 
A) bisphosphoglycerate phosphatase 
B) bisphosphoglycerate mutase 
C) 2,3-bisphosphoglycerate synthetase 
D) 1,3-bisphosphoglycerate hydrolase

Question 14

Which of the following products is formed when a-D-glucose reacts with ATP?

Accepted Answer

A) α-D-glucose-1-phosphate 
B) α-D-fructose-1-phosphate 
C) α-D-glucose-6-phosphate 
D) α-D-fructose-6-phosphate 
A) α-D-glucose-1-phosphate 
B) α-D-fructose-1-phosphate 
C) α-D-glucose-6-phosphate 
D) α-D-fructose-6-phosphate

Question 15

Which of the following enzymes,when genetically defective,can result in the most common form of hemolytic anemia?

Accepted Answer

A) pyruvate kinase 
B) hexokinase 
C) PFK-1 
D) phosphoglycerate mutase 
A) pyruvate kinase 
B) hexokinase 
C) PFK-1 
D) phosphoglycerate mutase

Question 16

What is the net ATP yield per glucose molecule at the end of the glycolytic pathway?

Accepted Answer

A) 1 
B) 2 
C) 3 
D) 4 
A) 1 
B) 2 
C) 3 
D) 4

Question 17

Which of the following is NOT an important reason to phosphorylate glucose in the first step of glycolysis?

Accepted Answer

A) The large positive free energy is important in getting the pathway started. 
B) Glucose-6-phosphate has a negative charge,preventing transport out of the cell. 
C) The concentration of free glucose in the cell is lowered,favouring influx of glucose. 
D) Regulatory control can be imposed only at a reaction,not at equilibrium. 
A) The large positive free energy is important in getting the pathway started. 
B) Glucose-6-phosphate has a negative charge,preventing transport out of the cell. 
C) The concentration of free glucose in the cell is lowered,favouring influx of glucose. 
D) Regulatory control can be imposed only at a reaction,not at equilibrium.

Question 18

Which of the following for 2,3-bisphosphoglycerate (2,3-BPG)is correct?

Accepted Answer

A) Erythrocytes typically have low levels of 2,3-BPG. 
B) 1,3-BPG is synthesized from 2,3-BPG. 
C) 2,3-BPG is involved in unloading oxygen from hemoglobin. 
D) A kinase converts 2,3-BPG to 3-phosphoglycerate. 
A) Erythrocytes typically have low levels of 2,3-BPG. 
B) 1,3-BPG is synthesized from 2,3-BPG. 
C) 2,3-BPG is involved in unloading oxygen from hemoglobin. 
D) A kinase converts 2,3-BPG to 3-phosphoglycerate.

Question 19

Which of the following is a characteristic of the coupling between glycolysis and the citric acid cycle?

Accepted Answer

A) Citrate inhibits glucokinase to regulate glycolysis. 
B) Glycolysis feeds acetyl-CoA,via pyruvate,to the citric acid cycle. 
C) Oxaloacetate builds up when the citric acid cycle reaches saturation. 
D) Glycolysis directs electrons into the electron transport chain for the purpose of ATP production. 
A) Citrate inhibits glucokinase to regulate glycolysis. 
B) Glycolysis feeds acetyl-CoA,via pyruvate,to the citric acid cycle. 
C) Oxaloacetate builds up when the citric acid cycle reaches saturation. 
D) Glycolysis directs electrons into the electron transport chain for the purpose of ATP production.

Question 20

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

Accepted Answer

A) Glucokinase acts on glucose only at high glucose concentrations. 
B) Glucokinase acts on glucose at low concentrations. 
C) Hexokinase acts on glucose only at high levels of glucose. 
D) Hexokinase acts at about half-maximal velocity at glucose concentrations of 4-5 mM. 
A) Glucokinase acts on glucose only at high glucose concentrations. 
B) Glucokinase acts on glucose at low concentrations. 
C) Hexokinase acts on glucose only at high levels of glucose. 
D) Hexokinase acts at about half-maximal velocity at glucose concentrations of 4-5 mM.

Exam 17: Glycolysis

Which of the following statements regarding sugar metabolism is correct?

Which enzyme is NOT involved in the first 5 steps of glycolysis?

Which of the following stable tautomers of pyruvate is formed during the conversion of PEP to pyruvate?

How is phosphofructokinase-1 regulated?

Which of the following is an allosteric effector of pyruvate kinase?

If glucose were labelled with ¹⁴C at carbon #6,which carbon of pyruvate would have the ¹⁴C?

Which of the following characterizes the conversion of glucose to lactate?

Which of the following is NOT a characteristic of the phosphofructokinase-1 catalyzed reaction?

Which of the following two proteins form the dimeric complex lactose synthase?

Which of the following enzymes is NOT used when fructose is metabolized to pyruvate in the liver?

Which of the following enzymes in the liver is used to phosphorylate fructose to fructose-1-phosphate?

Which of the following enzymes catalyzes substrate-level phosphorylation during glycolysis?

Which of the following enzymes catalyzes the reaction 1,3-bisphosphoglycerate ? 2,3-bisphosphoglycerate? -Which of the following enzymes catalyzes the reaction 1,3-bisphosphoglycerate ? 2,3-bisphosphoglycerate?

Which of the following products is formed when a-D-glucose reacts with ATP?

Which of the following enzymes,when genetically defective,can result in the most common form of hemolytic anemia?

What is the net ATP yield per glucose molecule at the end of the glycolytic pathway?

Which of the following is NOT an important reason to phosphorylate glucose in the first step of glycolysis?

Which of the following for 2,3-bisphosphoglycerate (2,3-BPG)is correct?

Which of the following is a characteristic of the coupling between glycolysis and the citric acid cycle?

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

The Facts of Life: Chemistry Is the Logic of Biological Phenomena

Water: the Medium of Life

Thermodynamics of Biological Systems

Amino Acids

Proteins: Their Primary Structure and Biological Functions

Proteins: Secondary, tertiary, and Quaternary Structure

Carbohydrates and the Glycoconjugates of Cell Surfaces

Lipids

Lipid Biosynthesis

Membranes and Membrane Transport

The Reception and Transmission of Extracellular Information

Enzymes Kinetics and Specificity

Mechanisms of Enzyme Action

Enzyme Regulation

Molecular Motors

Nutrition and the Organization of Metabolism

The Tricarboxylic Acid Cycle

Electron Transport and Oxidative Phosphorylation

Photosynthesis

Gluconeogenesis, glycogen Metabolism, and the Pentose Phosphate Pathway

Fatty Acid Catabolism

Nitrogen Acquisition and Amino Acid Metabolism

Nucleotides and Nucleic Acids

Structure of Nucleic Acids

Synthesis and Degradation of Nucleotides

Recombinant Dna: Cloning and Creation of Chimeric Genes

DNA Metabolism: Replication, recombination, and Repair

Transcription and the Regulation of Gene Expression

Protein Synthesis

Post-Transcriptional Regulation of Gene Expression

Completing the Protein Life Cycle: Folding, processing, and Degradation

Metabolic Integration and Organ Specialization

Filters

Glucokinase has a K_mvalue of 10.0 mM,whereas hexokinase has a K_m value of 0.1 mM.Which of the following is this consistent with?