Question 1

The glycogen debranching enzyme is required for

Accepted Answer

A) the transfer of 3-glucose units from one branch to another. 
B) the transfer of phosphate from one position to another. 
C) cleaving $\alpha$(1$\to$6)sugar linkages 
D) A and C 
E) A,B and C 
A) the transfer of 3-glucose units from one branch to another. 
B) the transfer of phosphate from one position to another. 
C) cleaving $\alpha$(1$\to$6)sugar linkages 
D) A and C 
E) A,B and C D

Question 2

Matching
Choose the correct answer from the list.Not all the answers will be used.

-Carboxylation of pyruvate in humans requires ______ as an essential dietary nutrient.

Accepted Answer

A)  phosphorylase a 
B)  gluconeogenesis 
C)  glucagon 
D)  glucose-6-phosphatase 
E)  cAMP
F)  biotin
G)  insulin
H) glycogenolysis
I) liver
J) glucose-1-phosphate
K) dolichol
L) muscle 
A)  phosphorylase a 
B)  gluconeogenesis 
C)  glucagon 
D)  glucose-6-phosphatase 
E)  cAMP
F)  biotin
G)  insulin
H) glycogenolysis
I) liver
J) glucose-1-phosphate
K) dolichol
L) muscle F

Question 3

Phosphoprotein phosphatase -1 (PP1)

Accepted Answer

A) catalyzes the phosphorylation of phosphorylase kinase. 
B) increases glycogen breakdown when active. 
C) catalyzes the dephosphorylation of phosphorylase kinase. 
D) catalyzes the dephosphorylation of glycogen phosphorylase. 
E) Both C and Dare correct. 
A) catalyzes the phosphorylation of phosphorylase kinase. 
B) increases glycogen breakdown when active. 
C) catalyzes the dephosphorylation of phosphorylase kinase. 
D) catalyzes the dephosphorylation of glycogen phosphorylase. 
E) Both C and Dare correct. E

Question 4

The diagram represents a "substrate cycle" in glucose metabolism.Which of the following statements about the cycle is true?

Accepted Answer

A) Reactions I & II are catalyzed by the same enzyme and help establish equilibrium between the two metabolites. 
B) Reaction II produces ATP by substrate-level phosphorylation. 
C) Reaction II is catalyzed by an allosteric enzyme that is inhibited by fructose-2-6-bisphosphate. 
D) Reaction I is involved in the biosynthesis of glucose. 
E) Reaction II occurs under low-energy conditions when the cell needs ATP. 
A) Reactions I & II are catalyzed by the same enzyme and help establish equilibrium between the two metabolites. 
B) Reaction II produces ATP by substrate-level phosphorylation. 
C) Reaction II is catalyzed by an allosteric enzyme that is inhibited by fructose-2-6-bisphosphate. 
D) Reaction I is involved in the biosynthesis of glucose. 
E) Reaction II occurs under low-energy conditions when the cell needs ATP.

Question 5

Which of the following aides in formation of a primer for glycogen synthesis ?

Accepted Answer

A) glycogen synthase 
B) UDP-glucose pyrophosphatate 
C) glycogenin 
D) UDP-glycogen 
E) amylo-(1,4 $\to$1,6)-transglycosylase 
A) glycogen synthase 
B) UDP-glucose pyrophosphatate 
C) glycogenin 
D) UDP-glycogen 
E) amylo-(1,4 $\to$1,6)-transglycosylase

Question 6

Which statement is true regarding the activation of pyruvate carboxylase by acetyl-CoA?

Accepted Answer

A) Feedback activation enhances flux through glycolysis. 
B) Feedforward activation enhances the entry of pyruvate through the TCA cycle as Acetyl-CoA. 
C) Ensures that gluconeogenesis occurs rather than pyruvate conversion to acetyl-CoA. 
D) Ensures that ATP is not wasted in the production of oxaloacetate. 
E) Feedback inhibition ensures that excess glucose-6-phosphate is not produced. 
A) Feedback activation enhances flux through glycolysis. 
B) Feedforward activation enhances the entry of pyruvate through the TCA cycle as Acetyl-CoA. 
C) Ensures that gluconeogenesis occurs rather than pyruvate conversion to acetyl-CoA. 
D) Ensures that ATP is not wasted in the production of oxaloacetate. 
E) Feedback inhibition ensures that excess glucose-6-phosphate is not produced.

Question 7

Which enzyme below is NOT required for the synthesis of branched glycogen?

Accepted Answer

A) glycogen phosphorylase 
B) glycogen synthase 
C) branching enzyme 
D) phosphoglucomutase 
E) All are required for synthesis of glycogen. 
A) glycogen phosphorylase 
B) glycogen synthase 
C) branching enzyme 
D) phosphoglucomutase 
E) All are required for synthesis of glycogen.

Question 8

Which of the following overall sequences is correct with regard to gluconeogenesis?

Accepted Answer

A) Oxaloacetate $\to$ PEP $\to$G6P $\to$ Glucose 
B) Pyruvate $\to$ FBP $\to$ PEP $\to$ Glucose 
C) Lactate $\to$ PEP $\to$ Pyruvate $\to$ G6P 
D) Oxaloacetate $\to$ F6P $\to$ FBP $\to$ Glucose 
E) F6P $\to$ FBP $\to$ Glucose $\to$ G6P 
A) Oxaloacetate $\to$ PEP $\to$G6P $\to$ Glucose 
B) Pyruvate $\to$ FBP $\to$ PEP $\to$ Glucose 
C) Lactate $\to$ PEP $\to$ Pyruvate $\to$ G6P 
D) Oxaloacetate $\to$ F6P $\to$ FBP $\to$ Glucose 
E) F6P $\to$ FBP $\to$ Glucose $\to$ G6P

Question 9

Matching
Choose the correct answer from the list.Not all the answers will be used.

-The breakdown of glycogen is referred to as ______.

Accepted Answer

A)  phosphorylase a 
B)  gluconeogenesis 
C)  glucagon 
D)  glucose-6-phosphatase 
E)  cAMP
F)  biotin
G)  insulin
H) glycogenolysis
I) liver
J) glucose-1-phosphate
K) dolichol
L) muscle 
A)  phosphorylase a 
B)  gluconeogenesis 
C)  glucagon 
D)  glucose-6-phosphatase 
E)  cAMP
F)  biotin
G)  insulin
H) glycogenolysis
I) liver
J) glucose-1-phosphate
K) dolichol
L) muscle

Question 10

Which of the following statements about glycogen is true?
(I)Glycogen is a polymer of glucose in $\alpha$(1$\to$6)linkages with $\alpha$(1$\to$4)linked branches every 8-14 residues.
(II)UDP-glucose is produced from glycogen by the action of the enzyme phosphorylase.
(III)In glycogen breakdown,glucose residues are sequentially removed from the nonreducing ends.
(IV)The breakdown of glycogen in skeletal muscle ultimately supplies glucose-6-phosphate,which can enter glycolysis to generate ATP.

Accepted Answer

A) I,II,III,IV 
B) I,II 
C) II,III,IV 
D) III,IV 
E) III only 
A) I,II,III,IV 
B) I,II 
C) II,III,IV 
D) III,IV 
E) III only

Question 11

Matching
Choose the correct answer from the list.Not all the answers will be used.

-The membrane-bound polyisoprenol involved in the synthesis of N-linked glycoproteins is called ______.

Accepted Answer

A)  phosphorylase a 
B)  gluconeogenesis 
C)  glucagon 
D)  glucose-6-phosphatase 
E)  cAMP
F)  biotin
G)  insulin
H) glycogenolysis
I) liver
J) glucose-1-phosphate
K) dolichol
L) muscle 
A)  phosphorylase a 
B)  gluconeogenesis 
C)  glucagon 
D)  glucose-6-phosphatase 
E)  cAMP
F)  biotin
G)  insulin
H) glycogenolysis
I) liver
J) glucose-1-phosphate
K) dolichol
L) muscle

Question 12

Patient "G" has a glycogen storage disease which results in decreased muscle glycogen levels.Muscle biopsies indicate poor glycogen structure in the muscle.Which of the following enzymes might be related to the cause?

Accepted Answer

A) muscle debranching enzyme 
B) muscle glycogen phosphorylase 
C) liver debranching enzyme 
D) muscle glycogen synthase 
E) liver glycogen synthase 
A) muscle debranching enzyme 
B) muscle glycogen phosphorylase 
C) liver debranching enzyme 
D) muscle glycogen synthase 
E) liver glycogen synthase

Question 13

Matching
Choose the correct answer from the list.Not all the answers will be used.

-______ cells lack receptors for the hormone glucagon.

Accepted Answer

A)  phosphorylase a 
B)  gluconeogenesis 
C)  glucagon 
D)  glucose-6-phosphatase 
E)  cAMP
F)  biotin
G)  insulin
H) glycogenolysis
I) liver
J) glucose-1-phosphate
K) dolichol
L) muscle 
A)  phosphorylase a 
B)  gluconeogenesis 
C)  glucagon 
D)  glucose-6-phosphatase 
E)  cAMP
F)  biotin
G)  insulin
H) glycogenolysis
I) liver
J) glucose-1-phosphate
K) dolichol
L) muscle

Question 14

Which of the following metabolic conversions involved in glucose synthesis requires the direct expenditure of ATP?
(I)3-Phosphoglycerate $\to$ 1,3-bisphosphoglycerate
(II)Glyceraldehyde-3-phosphate + dihydroxyacetone phosphate $\to$ fructose-1,6-bisphosphate
(III)Fructose-1,6-bisphosphate $\to$ fructose-6-phosphate
(IV)1,3-Bisphosphoglycerate $\to$ glyceraldehyde-3-phosphate

Accepted Answer

A) I only 
B) II,III 
C) III only 
D) II,IV 
E) I,IV 
A) I only 
B) II,III 
C) III only 
D) II,IV 
E) I,IV

Question 15

Which of the following metabolic conversions does not occur in gluconeogenesis?

Accepted Answer

A) oxaloacetate $\to$ phosphoenolpyruvate 
B) fructose-1,6-bisphosphate $\to$ fructose-6-phosphate 
C) GTP $\to$ CO2 + GDP 
D) NADH + H+ $\to$ NAD+ 
E) 1,3-bisphosphoglycerate $\to$ 3-phosphoglycerate 
A) oxaloacetate $\to$ phosphoenolpyruvate 
B) fructose-1,6-bisphosphate $\to$ fructose-6-phosphate 
C) GTP $\to$ CO2 + GDP 
D) NADH + H+ $\to$ NAD+ 
E) 1,3-bisphosphoglycerate $\to$ 3-phosphoglycerate

Question 16

Matching
Choose the correct answer from the list.Not all the answers will be used.

-The first step in the breakdown of glycogen is catalyzed by ______.

Accepted Answer

A)  phosphorylase a 
B)  gluconeogenesis 
C)  glucagon 
D)  glucose-6-phosphatase 
E)  cAMP
F)  biotin
G)  insulin
H) glycogenolysis
I) liver
J) glucose-1-phosphate
K) dolichol
L) muscle 
A)  phosphorylase a 
B)  gluconeogenesis 
C)  glucagon 
D)  glucose-6-phosphatase 
E)  cAMP
F)  biotin
G)  insulin
H) glycogenolysis
I) liver
J) glucose-1-phosphate
K) dolichol
L) muscle

Question 17

Which of the following serves as the free energy source for the metabolic conversion of oxaloacetate to phosphoenolpyruvate,which is catalyzed by PEP carboxykinase?

Accepted Answer

A) hydrolysis of PPi 
B) hydrolysis of ATP 
C) hydrolysis of GTP 
D) hydrolysis of an internal phosphoanhydride bond 
E) hydrolysis of a thioester intermediate 
A) hydrolysis of PPi 
B) hydrolysis of ATP 
C) hydrolysis of GTP 
D) hydrolysis of an internal phosphoanhydride bond 
E) hydrolysis of a thioester intermediate

Question 18

Which of the following best describes the role of fructose-2,6-bisphosphate (FBP)in liver cells?

Accepted Answer

A) It is an intermediate in glycolysis. 
B) It is an intermediate in gluconeogenesis. 
C) It is an intermediate in both glycolysis and gluconeogenesis. 
D) FBP is a potent allosteric activator of phosphofructokinase and an inhibitor of fructose bisphosphatase. 
E) FBP is a potent allosteric activator of fructose bisphosphatase and an inhibitor of phosphofructokinase. 
A) It is an intermediate in glycolysis. 
B) It is an intermediate in gluconeogenesis. 
C) It is an intermediate in both glycolysis and gluconeogenesis. 
D) FBP is a potent allosteric activator of phosphofructokinase and an inhibitor of fructose bisphosphatase. 
E) FBP is a potent allosteric activator of fructose bisphosphatase and an inhibitor of phosphofructokinase.

Question 19

What is the net ATP yield for a muscle cell that stores one dietary glucose molecule as glycogen and then releases it and sends it through glycolysis?

Accepted Answer

A) 0 
B) 1 
C) 2 
D) 3 
E) 4 
A) 0 
B) 1 
C) 2 
D) 3 
E) 4

Question 20

Which of the following best describes the function of the glycogen debranching enzyme in glycogenolysis?

Accepted Answer

A) It cleaves $\alpha$(1$\to$6)branch points releasing glucose-6-phosphate. 
B) It cleaves $\alpha$(1$\to$6)branch points releasing glucose-1-phosphate. 
C) It cleaves $\alpha$(1$\to$6)branch points releasing glucose. 
D) It transfers an $\alpha$(1$\to$4)linked trisaccharide unit to the nonreducing end of an alternate branch,then cleaves the $\alpha$(1$\to$6)branch point releasing glucose-1-phosphate. 
E) It transfers an $\alpha$(1$\to$4)linked trisaccharide to the nonreducing end of an alternate branch,then cleaves the $\alpha$(1$\to$6)branch point releasing glucose. 
A) It cleaves $\alpha$(1$\to$6)branch points releasing glucose-6-phosphate. 
B) It cleaves $\alpha$(1$\to$6)branch points releasing glucose-1-phosphate. 
C) It cleaves $\alpha$(1$\to$6)branch points releasing glucose. 
D) It transfers an $\alpha$(1$\to$4)linked trisaccharide unit to the nonreducing end of an alternate branch,then cleaves the $\alpha$(1$\to$6)branch point releasing glucose-1-phosphate. 
E) It transfers an $\alpha$(1$\to$4)linked trisaccharide to the nonreducing end of an alternate branch,then cleaves the $\alpha$(1$\to$6)branch point releasing glucose.

Exam 16: Glycogen Metabolism and Gluconeogenesis

The glycogen debranching enzyme is required for

Matching Choose the correct answer from the list.Not all the answers will be used. -Carboxylation of pyruvate in humans requires ______ as an essential dietary nutrient.

Phosphoprotein phosphatase -1 (PP1)

The diagram represents a "substrate cycle" in glucose metabolism.Which of the following statements about the cycle is true?

Which of the following aides in formation of a primer for glycogen synthesis ?

Which statement is true regarding the activation of pyruvate carboxylase by acetyl-CoA?

Which enzyme below is NOT required for the synthesis of branched glycogen?

Which of the following overall sequences is correct with regard to gluconeogenesis?

Matching Choose the correct answer from the list.Not all the answers will be used. -The breakdown of glycogen is referred to as ______.

Matching Choose the correct answer from the list.Not all the answers will be used. -The membrane-bound polyisoprenol involved in the synthesis of N-linked glycoproteins is called ______.

Patient "G" has a glycogen storage disease which results in decreased muscle glycogen levels.Muscle biopsies indicate poor glycogen structure in the muscle.Which of the following enzymes might be related to the cause?

Matching Choose the correct answer from the list.Not all the answers will be used. -______ cells lack receptors for the hormone glucagon.

Which of the following metabolic conversions does not occur in gluconeogenesis?

Matching Choose the correct answer from the list.Not all the answers will be used. -The first step in the breakdown of glycogen is catalyzed by ______.

Which of the following serves as the free energy source for the metabolic conversion of oxaloacetate to phosphoenolpyruvate,which is catalyzed by PEP carboxykinase?

Which of the following best describes the role of fructose-2,6-bisphosphate (FBP)in liver cells?

What is the net ATP yield for a muscle cell that stores one dietary glucose molecule as glycogen and then releases it and sends it through glycolysis?

Which of the following best describes the function of the glycogen debranching enzyme in glycogenolysis?

Introduction to the Chemistry of Life

Water

Nucleotides, nucleic Acids, and Genetic Information

Amino Acids

Proteins: Primary Structure

Proteins: Three-Dimensional Structure

Protein Function Part I: Myoglobin and Hemoglobin

Carbohydrates

Lipids and Biological Membranes

Membrane Transport

Enzyme Catalysis

Enzyme Kinetics, inhibition and Control

Biochemical Signaling

Introduction to Metabolism

Glucose Catabolism

Citric Acid Cycle

Electron Transport and Oxidative Phosphorylation

Photosynthesis

Lipid Metabolism

Amino Acid Metabolism

Mammalian Fuel Metabolism: Integration and Regulation

Nucleotide Metabolism

Nucleic Acid Structure

DNA Replication, repair and Recombination

Transcription and Rna Processing

Protein Synthesis

Regulation of Gene Expression

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