Question 1

The pentose phosphate pathway occurs in the

Accepted Answer

A)  cytoplasm. 
B)  nucleus. 
C)  Golgi apparatus. 
D)  mitochondria. 
A)  cytoplasm. 
B)  nucleus. 
C)  Golgi apparatus. 
D)  mitochondria.

Question 2

The branching enzyme

Accepted Answer

A)  couples the formation of glycogen with UDP loss from UDP-glucose. 
B)  makes $\alpha$(1,4) linkages with the transfer of seven glucose units. 
C)  breaks $\alpha$(1,6) branch points and remakes $\alpha$(1,4) linkages. 
D)  catalyzes the cleavage of $\alpha$(1,4) links and the formation of $\alpha$(1,6) links. 
A)  couples the formation of glycogen with UDP loss from UDP-glucose. 
B)  makes $\alpha$(1,4) linkages with the transfer of seven glucose units. 
C)  breaks $\alpha$(1,6) branch points and remakes $\alpha$(1,4) linkages. 
D)  catalyzes the cleavage of $\alpha$(1,4) links and the formation of $\alpha$(1,6) links.

Question 3

The gluconeogenesis pathway

Accepted Answer

A)  converts NADH into NAD+ so that glycolysis can continue. 
B)  provides energy for the cell. 
C)  increases the ratio of ATP to ADP in the cell. 
D)  converts two 3C sugars into a 6C sugar. 
A)  converts NADH into NAD+ so that glycolysis can continue. 
B)  provides energy for the cell. 
C)  increases the ratio of ATP to ADP in the cell. 
D)  converts two 3C sugars into a 6C sugar.

Question 4

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 5

Draw a diagram indicating the organs, metabolic pathways, and key molecules involved in the circular Cori cycle.

Accepted Answer

The answer of Draw a diagram indicating the organs, metabolic...

Question 6

State how glucagon functions to increase blood glucose levels.

Accepted Answer

It activates a phosphorylation cascade t

Question 7

Which enzyme class catalyzes the following pentose phosphate pathway reaction (note that there may be some missing reactants and products)?

Accepted Answer

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

Question 8

What molecules are missing from boxes in the gluconeogenesis reaction shown below?

Accepted Answer

A)  Ser-Pi; Ser-Pi 
B)  H2O; Pi 
C)  ADP; ATP 
D)  ATP; ADP 
A)  Ser-Pi; Ser-Pi 
B)  H2O; Pi 
C)  ADP; ATP 
D)  ATP; ADP

Question 9

Which correctly describes the role of the transport system shown below?

Accepted Answer

A)  It provides an alternate fate for pyruvate degradation. 
B)  It provides a source of NADH for gluconeogenesis via malate transport. 
C)  It converts NADH equivalents into reduced forms of carbon. 
D)  It allows for pyruvate transport into and out of the mitochondria. 
A)  It provides an alternate fate for pyruvate degradation. 
B)  It provides a source of NADH for gluconeogenesis via malate transport. 
C)  It converts NADH equivalents into reduced forms of carbon. 
D)  It allows for pyruvate transport into and out of the mitochondria.

Question 10

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 11

Starting from the oxidative phase of the pentose phosphate pathway, how many ATP and high-energy reduced molecules, respectively, are made in going from one glucose molecule to glyceraldehyde-3-phosphate and fructose-6-phosphate?

Accepted Answer

A)  0; 0 
B)  0; 2 
C)  2; 0 
D)  2; 2 
A)  0; 0 
B)  0; 2 
C)  2; 0 
D)  2; 2

Question 12

What controls the activity of the opposing enzymes hexokinase and glucose-6-phosphatase from the glycolysis and gluconeogenesis pathways?

Accepted Answer

A)  levels of ATP 
B)  cellular compartmentalization and separation of the two enzymes 
C)  fructose-2,6-bisphosphate concentration 
D)  phosphorylation of the enzymes 
A)  levels of ATP 
B)  cellular compartmentalization and separation of the two enzymes 
C)  fructose-2,6-bisphosphate concentration 
D)  phosphorylation of the enzymes

Question 13

Of the four molecules listed below, three of them reciprocally regulate phosphofructokinase 1 (PFK1) and fructose-1,6-bisphosphatase. Which molecule does NOT fit?

Accepted Answer

A)  pyruvate 
B)  fructose-2,6-bisphosphate 
C)  citrate 
D)  AMP 
A)  pyruvate 
B)  fructose-2,6-bisphosphate 
C)  citrate 
D)  AMP

Question 14

In the glycogenesis pathway, which enzyme catalyzes the formation of $\alpha$(1,6) linkages?

Accepted Answer

A)  debranching enzyme 
B)  glycogen synthase 
C)  glycogen phosphorylase 
D)  branching enzyme 
A)  debranching enzyme 
B)  glycogen synthase 
C)  glycogen phosphorylase 
D)  branching enzyme

Question 15

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 16

von Gierke disease is a common glycogen storage disease caused by a deficiency in glucose-6-phosphatase. Explain how a deficiency in this gluconeogenesis enzyme leads to glycogen storage issues.

Accepted Answer

A deficiency in glucose-6-phosphatase gi

Question 17

Fill in the names of the enzymes involved in the important cellular glutathione detoxification system shown below.

Accepted Answer

The answer of Fill in the names of the enzymes...

Question 18

Draw a glucose molecule and indicate which atom is linked to glycogen during the glycogen synthesis process.

Accepted Answer

The C1 of the incomi

Question 19

Which pathway is opposite to gluconeogenesis?

Accepted Answer

A)  TCA cycle 
B)  glycogen synthesis pathway 
C)  pentose phosphate pathway 
D)  glycolysis pathway 
A)  TCA cycle 
B)  glycogen synthesis pathway 
C)  pentose phosphate pathway 
D)  glycolysis pathway

Question 20

The pentose phosphate pathway

Accepted Answer

A)  resembles the TCA cycle in that it couples the loss of CO2 with the formation of NADH. 
B)  allows 5C sugars to converge with or diverge from the glycolysis pathway. 
C)  contains 2C, 3C, 4C, 5C, 6C, and 7C sugar molecules. 
D)  enables the production of ATP from glucose. 
A)  resembles the TCA cycle in that it couples the loss of CO2 with the formation of NADH. 
B)  allows 5C sugars to converge with or diverge from the glycolysis pathway. 
C)  contains 2C, 3C, 4C, 5C, 6C, and 7C sugar molecules. 
D)  enables the production of ATP from glucose.

Exam 14: Carbohydrate Metabolism

The pentose phosphate pathway occurs in the

The branching enzyme

The gluconeogenesis pathway

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

Draw a diagram indicating the organs, metabolic pathways, and key molecules involved in the circular Cori cycle.

State how glucagon functions to increase blood glucose levels.

Which enzyme class catalyzes the following pentose phosphate pathway reaction (note that there may be some missing reactants and products)?

What molecules are missing from boxes in the gluconeogenesis reaction shown below?

Which correctly describes the role of the transport system shown below?

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

Starting from the oxidative phase of the pentose phosphate pathway, how many ATP and high-energy reduced molecules, respectively, are made in going from one glucose molecule to glyceraldehyde-3-phosphate and fructose-6-phosphate?

What controls the activity of the opposing enzymes hexokinase and glucose-6-phosphatase from the glycolysis and gluconeogenesis pathways?

Of the four molecules listed below, three of them reciprocally regulate phosphofructokinase 1 (PFK1) and fructose-1,6-bisphosphatase. Which molecule does NOT fit?

In the glycogenesis pathway, which enzyme catalyzes the formation of α\alphaα (1,6) linkages?

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

von Gierke disease is a common glycogen storage disease caused by a deficiency in glucose-6-phosphatase. Explain how a deficiency in this gluconeogenesis enzyme leads to glycogen storage issues.

Fill in the names of the enzymes involved in the important cellular glutathione detoxification system shown below.

Draw a glucose molecule and indicate which atom is linked to glycogen during the glycogen synthesis process.

Which pathway is opposite to gluconeogenesis?

The pentose phosphate pathway

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

Filters

In the glycogenesis pathway, which enzyme catalyzes the formation of $\alpha$ (1,6) linkages?