Question 1

State the role of the liver and the role of the muscles and explain their need for different glycogen metabolism regulation.

Accepted Answer

The liver stores glycogen to meet the ne

Question 2

State whether enzymes are phosphorylated or dephosphorylated in the glycogen metabolism pathways on the binding of adrenaline to liver or muscle cell receptors and state how this affects their activity.

Accepted Answer

Adrenaline leads to the phosph

Question 3

A patient is found to have a mutated enzyme that results in fewer branch points in glycogen.Which one of the following would best characterize the way in which the patient's glycogen is altered relative to normal glycogen?

Accepted Answer

A)   
B)  a change in the stereochemical configuration at the reducing end 
C)   
D)  a decreased ratio of nonreducing to reducing ends 
A)   
B)  a change in the stereochemical configuration at the reducing end 
C)   
D)  a decreased ratio of nonreducing to reducing ends

Question 4

Which enzyme in the glycolysis pathway catalyzes a reaction that requires two enzymes to reverse in the gluconeogenesis pathway?

Accepted Answer

A)  pyruvate kinase 
B)  phosphofructokinase I 
C)  pyruvate dehydrogenase 
D)  glycogen phosphorylase 
A)  pyruvate kinase 
B)  phosphofructokinase I 
C)  pyruvate dehydrogenase 
D)  glycogen phosphorylase

Question 5

Which of the following metabolites is NOT a gluconeogenesis substrate in humans?

Accepted Answer

A)  pyruvate 
B)  lactate 
C)  oxaloacetate 
D)  acetate 
A)  pyruvate 
B)  lactate 
C)  oxaloacetate 
D)  acetate

Question 6

Why is it important that muscle cells are unresponsive to glucagon?

Accepted Answer

A)  Muscle cells store glycogen for its own energy needs and not the needs of other tissues. 
B)  The muscles do not store glycogen. 
C)  The muscles release glucose to other tissues in need. 
D)  Muscle cells respond to insulin instead. 
A)  Muscle cells store glycogen for its own energy needs and not the needs of other tissues. 
B)  The muscles do not store glycogen. 
C)  The muscles release glucose to other tissues in need. 
D)  Muscle cells respond to insulin instead.

Question 7

Which pair of opposite enzymes in the glycolysis and gluconeogenesis pathway are not allosterically regulated but rather regulated by compartmentalization?

Accepted Answer

A)  pyruvate kinase/PEP carboxykinase 
B)  phosphofructokinase 1/fructose-1,6-bisphosphatase 
C)  phosphofructokinase 2/fructose-2,6-bisphosphatase 
D)  hexokinase/glucose-6-phosphatase 
A)  pyruvate kinase/PEP carboxykinase 
B)  phosphofructokinase 1/fructose-1,6-bisphosphatase 
C)  phosphofructokinase 2/fructose-2,6-bisphosphatase 
D)  hexokinase/glucose-6-phosphatase

Question 8

In the breakdown of glycogen by glycogen phosphorylase,the immediate predominant product is

Accepted Answer

A)  glucose. 
B)  glucose-1-phosphate. 
C)  UDP-glucose. 
D)  glucose-6-phosphate. 
A)  glucose. 
B)  glucose-1-phosphate. 
C)  UDP-glucose. 
D)  glucose-6-phosphate.

Question 9

In the gluconeogenesis pathway,the enzyme glucose-6-phosphatase reverses which step in glycolysis?

Accepted Answer

A)  the formation of glucose 
B)  the reaction catalyzed by pyruvate dehydrogenase 
C)  the reaction catalyzed by hexokinase 
D)  the formation of fructose-1,6-bisphosphate 
A)  the formation of glucose 
B)  the reaction catalyzed by pyruvate dehydrogenase 
C)  the reaction catalyzed by hexokinase 
D)  the formation of fructose-1,6-bisphosphate

Question 10

How would individuals with decreased levels of the pentose phosphate enzyme glucose-6-phosphate dehydrogenase respond to oxidative stress?

Accepted Answer

A)  Higher than normal levels of NADPH would accumulate. 
B)  They would not have the ability to regenerate reduced glutathione as rapidly. 
C)  They would rapidly neutralize cellular levels of H2O2 and other reactive oxygen species. 
D)  They would compensate with higher than normal levels of pentose phosphate pathway activity. 
A)  Higher than normal levels of NADPH would accumulate. 
B)  They would not have the ability to regenerate reduced glutathione as rapidly. 
C)  They would rapidly neutralize cellular levels of H2O2 and other reactive oxygen species. 
D)  They would compensate with higher than normal levels of pentose phosphate pathway activity.

Question 11

Cytoplasmic levels of NADH must be maintained in order for gluconeogenesis to occur.What generates NADH for this pathway?

Accepted Answer

A)  the glycolysis pathway 
B)  the TCA cycle 
C)  the mitochondrial electron transport chain 
D)  the movement of NADH equivalents from inside the mitochondria via malate transport 
A)  the glycolysis pathway 
B)  the TCA cycle 
C)  the mitochondrial electron transport chain 
D)  the movement of NADH equivalents from inside the mitochondria via malate transport

Question 12

What is the cellular role of glutathione in red blood cells?

Accepted Answer

Glutathione acts as an antioxidant to pr

Question 13

Which of the following is NOT a role played by the pentose phosphate pathway?

Accepted Answer

A)  converting pyruvate into TCA cycle intermediates 
B)  making NADPH for other metabolic pathways 
C)  converting 6C glucose into 5C ribose 
D)  converting DNA backbone sugars into glycolysis intermediates 
A)  converting pyruvate into TCA cycle intermediates 
B)  making NADPH for other metabolic pathways 
C)  converting 6C glucose into 5C ribose 
D)  converting DNA backbone sugars into glycolysis intermediates

Question 14

The debranching enzyme does NOT catalyze the

Accepted Answer

A)    
B) 
  
C)    
D)    
A)    
B) 
  
C)    
D)

Question 15

Which enzyme class catalyzes the following pentose phosphate pathway reaction?

Accepted Answer

A)  lyase 
B)  transferase 
C)  oxidoreductase 
D)  isomerase 
A)  lyase 
B)  transferase 
C)  oxidoreductase 
D)  isomerase

Question 16

Which of the following molecules is found in the nonoxidative phase of the pentose phosphate pathway?

Accepted Answer

A)  ATP 
B)  NADPH 
C)  fructose-6-phosphate 
D)  CO2 
A)  ATP 
B)  NADPH 
C)  fructose-6-phosphate 
D)  CO2

Question 17

The Cori cycle

Accepted Answer

A)  transports pyruvate from working muscles to the liver, where it is converted back to glucose. 
B)  is important in organisms respiring aerobically. 
C)  involves the conversion of muscle pyruvate to alanine followed by transport to the liver. 
D)  relies on functioning lactate dehydrogenase in both muscle and liver tissues. 
A)  transports pyruvate from working muscles to the liver, where it is converted back to glucose. 
B)  is important in organisms respiring aerobically. 
C)  involves the conversion of muscle pyruvate to alanine followed by transport to the liver. 
D)  relies on functioning lactate dehydrogenase in both muscle and liver tissues.

Question 18

The enzymes that catalyze the regulated steps in glycolysis are

Accepted Answer

A)  phosphofructokinase, pyruvate dehydrogenase, and lactate dehydrogenase. 
B)  hexokinase, phosphofructokinase, and pyruvate dehydrogenase. 
C)  aldolase, phosphofructokinase, and pyruvate kinase. 
D)  hexokinase, phosphofructokinase, and pyruvate kinase. 
A)  phosphofructokinase, pyruvate dehydrogenase, and lactate dehydrogenase. 
B)  hexokinase, phosphofructokinase, and pyruvate dehydrogenase. 
C)  aldolase, phosphofructokinase, and pyruvate kinase. 
D)  hexokinase, phosphofructokinase, and pyruvate kinase.

Question 19

Give the overall balanced reaction for the gluconeogenesis pathway,beginning from pyruvate.Please include any energy currency molecules required by the pathway.

Accepted Answer

2 pyruvate + 2NADH +

Question 20

The role of glycogenin is to

Accepted Answer

A)  catalyze the formation of UDP-glucose. 
B)  act as a hormone to regulate glucose levels. 
C)  serve as the origin of the glycogen polymer. 
D)  enable glycogen to fold properly. 
A)  catalyze the formation of UDP-glucose. 
B)  act as a hormone to regulate glucose levels. 
C)  serve as the origin of the glycogen polymer. 
D)  enable glycogen to fold properly.

Exam 14: Carbohydrate Metabolism

State the role of the liver and the role of the muscles and explain their need for different glycogen metabolism regulation.

State whether enzymes are phosphorylated or dephosphorylated in the glycogen metabolism pathways on the binding of adrenaline to liver or muscle cell receptors and state how this affects their activity.

A patient is found to have a mutated enzyme that results in fewer branch points in glycogen.Which one of the following would best characterize the way in which the patient's glycogen is altered relative to normal glycogen?

Which enzyme in the glycolysis pathway catalyzes a reaction that requires two enzymes to reverse in the gluconeogenesis pathway?

Which of the following metabolites is NOT a gluconeogenesis substrate in humans?

Why is it important that muscle cells are unresponsive to glucagon?

Which pair of opposite enzymes in the glycolysis and gluconeogenesis pathway are not allosterically regulated but rather regulated by compartmentalization?

In the breakdown of glycogen by glycogen phosphorylase,the immediate predominant product is

In the gluconeogenesis pathway,the enzyme glucose-6-phosphatase reverses which step in glycolysis?

How would individuals with decreased levels of the pentose phosphate enzyme glucose-6-phosphate dehydrogenase respond to oxidative stress?

Cytoplasmic levels of NADH must be maintained in order for gluconeogenesis to occur.What generates NADH for this pathway?

What is the cellular role of glutathione in red blood cells?

Which of the following is NOT a role played by the pentose phosphate pathway?

The debranching enzyme does NOT catalyze the

Which enzyme class catalyzes the following pentose phosphate pathway reaction?

Which of the following molecules is found in the nonoxidative phase of the pentose phosphate pathway?

The Cori cycle

The enzymes that catalyze the regulated steps in glycolysis are

Give the overall balanced reaction for the gluconeogenesis pathway,beginning from pyruvate.Please include any energy currency molecules required by the pathway.

The role of glycogenin is to

Principles of Biochemistry

Physical Biochemistry: Energy Conversion,water,and Membranes

Nucleic Acid Structure and Function

Protein Structure

Methods in Protein Biochemistry

Protein Function

Enzyme Mechanisms

Cell Signaling Systems

Glycolysis: a Paradigm of Metabolic Regulation

The Citrate Cycle

Oxidative Phosphorylation

Photosynthesis

Carbohydrate Structure and Function

Lipid Structure and Function

Lipid Metabolism

Amino Acid Metabolism

Nucleotide Metabolism

Metabolic Integration

Dna Replication, repair, and Recombination

Rna Synthesis, processing, and Gene Silencing

Protein Synthesis, posttranslational Modification, and Transport

Gene Regulation

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