Question 1

Which statement about gluconeogenesis is FALSE?

Accepted Answer

A)  For starting materials, it can use carbon skeletons derived from certain amino acids. 
B)  It consists entirely of the reactions of glycolysis, operating in the reverse direction. 
C)  It employs the enzyme glucose 6-phosphatase. 
D)  It is one of the ways that mammals maintain normal blood glucose levels between meals. 
E)  It requires metabolic energy (ATP or GTP). 
A)  For starting materials, it can use carbon skeletons derived from certain amino acids. 
B)  It consists entirely of the reactions of glycolysis, operating in the reverse direction. 
C)  It employs the enzyme glucose 6-phosphatase. 
D)  It is one of the ways that mammals maintain normal blood glucose levels between meals. 
E)  It requires metabolic energy (ATP or GTP).

Question 2

The oxidation of 3 mol of glucose by the pentose phosphate pathway may result in the production of:

Accepted Answer

A)  2 mol of pentose, 4 mol of NADPH, and 8 mol of CO2. 
B)  3 mol of pentose, 4 mol of NADPH, and 3 mol of CO2. 
C)  3 mol of pentose, 6 mol of NADPH, and 3 mol of CO2. 
D)  4 mol of pentose, 3 mol of NADPH, and 3 mol of CO2. 
E)  4 mol of pentose, 6 mol of NADPH, and 6 mol of CO2. 
A)  2 mol of pentose, 4 mol of NADPH, and 8 mol of CO2. 
B)  3 mol of pentose, 4 mol of NADPH, and 3 mol of CO2. 
C)  3 mol of pentose, 6 mol of NADPH, and 3 mol of CO2. 
D)  4 mol of pentose, 3 mol of NADPH, and 3 mol of CO2. 
E)  4 mol of pentose, 6 mol of NADPH, and 6 mol of CO2.

Question 3

Which statement is INCORRECT?

Accepted Answer

A)  Aerobically, oxidative decarboxylation of pyruvate forms acetate that enters the citric acid cycle. 
B)  In anaerobic muscle, pyruvate is converted to lactate. 
C)  In yeast growing anaerobically, pyruvate is converted to ethanol. 
D)  Reduction of pyruvate to lactate regenerates a cofactor essential for glycolysis. 
E)  Under anaerobic conditions pyruvate does not form because glycolysis does not occur. 
A)  Aerobically, oxidative decarboxylation of pyruvate forms acetate that enters the citric acid cycle. 
B)  In anaerobic muscle, pyruvate is converted to lactate. 
C)  In yeast growing anaerobically, pyruvate is converted to ethanol. 
D)  Reduction of pyruvate to lactate regenerates a cofactor essential for glycolysis. 
E)  Under anaerobic conditions pyruvate does not form because glycolysis does not occur.

Question 4

If glucose, radioactively labeled in the C-2 position with 14C, is used as a substrate in a yeast extract maintained under strictly anaerobic conditions, what is the location of 14C in the product ethanol?

Accepted Answer

A)  14CH3-CH2-OH 
B)  CH3-14CH2-OH 
C)  CH3-CHOH-14COO- 
D)  It is released as 14CO2 by pyruvate decarboxylase and never becomes part of ethanol. 
E)  It is released as 14CO2 by alcohol dehydrogenase and never becomes part of ethanol. 
A)  14CH3-CH2-OH 
B)  CH3-14CH2-OH 
C)  CH3-CHOH-14COO- 
D)  It is released as 14CO2 by pyruvate decarboxylase and never becomes part of ethanol. 
E)  It is released as 14CO2 by alcohol dehydrogenase and never becomes part of ethanol.

Question 5

Explain why Pi (inorganic phosphate) is absolutely required for glycolysis to proceed.

Accepted Answer

Inorganic phosphate (Pi) is absolutely r

Question 6

Which substrate CANNOT contribute to net gluconeogenesis in mammalian liver?

Accepted Answer

A)  alanine 
B)  glutamate 
C)  palmitate 
D)  pyruvate 
E)  $\alpha$-ketoglutarate 
A)  alanine 
B)  glutamate 
C)  palmitate 
D)  pyruvate 
E)  $\alpha$-ketoglutarate

Question 7

Which carbon atom in one of the glycolytic intermediates shown below would have to be radiolabeled with 14C in order to ensure all the radioactivity would be release as 14CO2 during alcoholic fermentation?

Accepted Answer

A)  C6 of glucose 6-phosphate. 
B)  C3 of fructose 1,6-bisphosphate. 
C)  C1 of pyruvate. 
D)  C2 of glyceraldehyde 3-phosphate. 
E)  C5 of fructose 6-phosphate. 
A)  C6 of glucose 6-phosphate. 
B)  C3 of fructose 1,6-bisphosphate. 
C)  C1 of pyruvate. 
D)  C2 of glyceraldehyde 3-phosphate. 
E)  C5 of fructose 6-phosphate.

Question 8

When a mixture of glucose 6-phosphate and fructose 6-phosphate is incubated with the enzyme phosphohexose isomerase, the final mixture contains twice as much glucose 6-phosphate as fructose 6-phosphate. Which statement is MOST nearly correct, when applied to the reaction below (R = 8.315 J/mol · K and T = 298 K)? glucose 6-phosphate $\leftrightarrow$ fructose 6-phosphate

Accepted Answer

A)  $\Delta$G'° is +1.7 kJ/mol. 
B)  $\Delta$G'° is -1.7 kJ/mol. 
C)  $\Delta$G'° is incalculably large and negative. 
D)  $\Delta$G'° is incalculably large and positive. 
E)  $\Delta$G'° is zero. 
A)  $\Delta$G'° is +1.7 kJ/mol. 
B)  $\Delta$G'° is -1.7 kJ/mol. 
C)  $\Delta$G'° is incalculably large and negative. 
D)  $\Delta$G'° is incalculably large and positive. 
E)  $\Delta$G'° is zero.

Question 9

If brewer's yeast is mixed with pure sugar (glucose) in the absence of phosphate (Pi), no ethanol is produced. With the addition of a little Pi, ethanol production soon begins. Explain this observation in 25 words or less.

Accepted Answer

The presence of phosphate is n

Question 10

Which cofactor participates directly in most of the oxidation-reduction reactions in the fermentation of glucose to lactate?

Accepted Answer

A)  ADP 
B)  ATP 
C)  FAD/FADH2 
D)  glyceraldehyde 3-phosphate 
E)  NAD+/NADH 
A)  ADP 
B)  ATP 
C)  FAD/FADH2 
D)  glyceraldehyde 3-phosphate 
E)  NAD+/NADH

Question 11

If glucose labeled with 14C at C-2 were metabolized in the liver, the first radioactive pyruvate formed would be labeled in:

Accepted Answer

A)  all three carbons. 
B)  both its carbonyl and carboxyl carbons. 
C)  its carbonyl carbon. 
D)  its carboxyl carbon. 
E)  its methyl carbon. 
A)  all three carbons. 
B)  both its carbonyl and carboxyl carbons. 
C)  its carbonyl carbon. 
D)  its carboxyl carbon. 
E)  its methyl carbon.

Question 12

At which point in glycolysis do C-3 and C-4 of glucose become chemically equivalent?

Accepted Answer

In the glycolytic pathway, C-3 (carbon 3

Question 13

Explain the biochemical basis of the human metabolic disorder called lactose intolerance.

Accepted Answer

Lactose intolerance is a common metaboli

Question 14

Glyceraldehyde 3-phosphate (GAP) that is labeled with 14C in a single carbon atom was added to a yeast cytoplasmic extract. After a short period of time, fructose 1,6-bisphosphate was produced that was labeled at carbons 3 and 4.
a) What was the location of the radiolabeled carbon in the GAP molecule?
b) Where did the second 14C label if fructose 1,6-bisphosphate come from?

Accepted Answer

a) The radiolabeled carbon in

Question 15

Glycolysis is the name given to a metabolic pathway occurring in many different cell types. It consists of 11 enzymatic steps that convert glucose to lactic acid. Glycolysis is an example of:

Accepted Answer

A)  aerobic metabolism. 
B)  anabolic metabolism. 
C)  a net reductive process. 
D)  fermentation. 
E)  oxidative phosphorylation. 
A)  aerobic metabolism. 
B)  anabolic metabolism. 
C)  a net reductive process. 
D)  fermentation. 
E)  oxidative phosphorylation.

Question 16

In glycolysis there are two reactions that require one ATP each and two reactions that produce one ATP each. This being the case, how can fermentation of glucose to lactate lead to the net production of two ATP molecules per glucose?

Accepted Answer

Glycolysis is a metabolic pathway that b

Question 17

Describe the process of glycogen breakdown in muscle. Include a description of the structure of glycogen, the nature of the breakdown reaction and the breakdown product, and the required enzyme(s).

Accepted Answer

Glycogen is a highly branched polysaccha

Question 18

The enzyme 2,3-BPG mutase produces 1,3-BPG in red blood cells through an isomerization (rearrangement) reaction. What amino acid(s) would you predict to be important in substrate binding?

Accepted Answer

A)  Asp 
B)  Glu 
C)  Lys 
D)  Leu 
E)  both Asp and Glu 
A)  Asp 
B)  Glu 
C)  Lys 
D)  Leu 
E)  both Asp and Glu

Question 19

Galactosemia is a genetic error of metabolism associated with:

Accepted Answer

A)  deficiency of galactokinase. 
B)  deficiency of UDP-glucose. 
C)  deficiency of UDP-glucose: galactose 1-phosphate uridylyltransferase. 
D)  excessive ingestion of galactose. 
E)  inability to digest lactose. 
A)  deficiency of galactokinase. 
B)  deficiency of UDP-glucose. 
C)  deficiency of UDP-glucose: galactose 1-phosphate uridylyltransferase. 
D)  excessive ingestion of galactose. 
E)  inability to digest lactose.

Question 20

Which amount of ATP and NADH identifies net production when 3 mol of ribulose 5-phosphate are converted to pyruvate?

Accepted Answer

A)  4 mol of ATP and 2 mol of NADH 
B)  5 mol of ATP and 3 mol of NADH 
C)  8 mol of ATP and 5 mol of NADH 
D)  10 mol of ATP and 5 mol of NADH 
E)  10 mol of ATP and 6 mol of NADH 
A)  4 mol of ATP and 2 mol of NADH 
B)  5 mol of ATP and 3 mol of NADH 
C)  8 mol of ATP and 5 mol of NADH 
D)  10 mol of ATP and 5 mol of NADH 
E)  10 mol of ATP and 6 mol of NADH

Exam 14: Glycolysis, Gluconeogenesis, and the Pentose Phosphate Pathway

Which statement about gluconeogenesis is FALSE?

The oxidation of 3 mol of glucose by the pentose phosphate pathway may result in the production of:

Which statement is INCORRECT?

If glucose, radioactively labeled in the C-2 position with 14C, is used as a substrate in a yeast extract maintained under strictly anaerobic conditions, what is the location of 14C in the product ethanol?

Explain why Pi (inorganic phosphate) is absolutely required for glycolysis to proceed.

Which substrate CANNOT contribute to net gluconeogenesis in mammalian liver?

Which carbon atom in one of the glycolytic intermediates shown below would have to be radiolabeled with 14C in order to ensure all the radioactivity would be release as 14CO2 during alcoholic fermentation?

If brewer's yeast is mixed with pure sugar (glucose) in the absence of phosphate (Pi), no ethanol is produced. With the addition of a little Pi, ethanol production soon begins. Explain this observation in 25 words or less.

Which cofactor participates directly in most of the oxidation-reduction reactions in the fermentation of glucose to lactate?

If glucose labeled with 14C at C-2 were metabolized in the liver, the first radioactive pyruvate formed would be labeled in:

At which point in glycolysis do C-3 and C-4 of glucose become chemically equivalent?

Explain the biochemical basis of the human metabolic disorder called lactose intolerance.

Glycolysis is the name given to a metabolic pathway occurring in many different cell types. It consists of 11 enzymatic steps that convert glucose to lactic acid. Glycolysis is an example of:

In glycolysis there are two reactions that require one ATP each and two reactions that produce one ATP each. This being the case, how can fermentation of glucose to lactate lead to the net production of two ATP molecules per glucose?

Describe the process of glycogen breakdown in muscle. Include a description of the structure of glycogen, the nature of the breakdown reaction and the breakdown product, and the required enzyme(s).

The enzyme 2,3-BPG mutase produces 1,3-BPG in red blood cells through an isomerization (rearrangement) reaction. What amino acid(s) would you predict to be important in substrate binding?

Galactosemia is a genetic error of metabolism associated with:

Which amount of ATP and NADH identifies net production when 3 mol of ribulose 5-phosphate are converted to pyruvate?

The Foundations of Biochemistry

Water

Amino Acids, Peptides, and Proteins

The Three-Dimensional Structure of Proteins

Protein Function

Enzymes

Carbohydrates and Glycobiology

Nucleotides and Nucleic Acids

DNA-Based Information Technologies

Lipids

Biological Membranes and Transport

Biosignaling

Bioenergetics and Biochemical Reaction Types

Principles of Metabolic Regulation

The Citric Acid Cycle

Fatty Acid Catabolism

Amino Acid Oxidation and the Production of Urea

Oxidative Phosphorylation and Photophosphorylation

Carbohydrate Biosynthesis in Plants and Bacteria

Lipid Biosynthesis

Biosynthesis of Amino Acids, Nucleotides, and Related Molecules

Hormonal Regulation and Integration of Mammalian Metabolism

Genes and Chromosomes

DNA Metabolism

RNA Metabolism

Protein Metabolism

Regulation of Gene Expression

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If glucose, radioactively labeled in the C-2 position with ¹⁴C, is used as a substrate in a yeast extract maintained under strictly anaerobic conditions, what is the location of ¹⁴C in the product ethanol?

Explain why P_i (inorganic phosphate) is absolutely required for glycolysis to proceed.

Which carbon atom in one of the glycolytic intermediates shown below would have to be radiolabeled with ¹⁴C in order to ensure all the radioactivity would be release as ¹⁴CO₂ during alcoholic fermentation?

If brewer's yeast is mixed with pure sugar (glucose) in the absence of phosphate (P_i), no ethanol is produced. With the addition of a little P_i, ethanol production soon begins. Explain this observation in 25 words or less.

If glucose labeled with ¹⁴C at C-2 were metabolized in the liver, the first radioactive pyruvate formed would be labeled in: