Question 1

Which of the following statements is not true concerning glycolysis in anaerobic muscle?

Accepted Answer

A) Fructose 1,6-bisphosphatase is one of the enzymes of the pathway. 
B) It is an endergonic process. 
C) It results in net synthesis of ATP. 
D) It results in synthesis of NADH. 
E) Its rate is slowed by a high [ATP]/[ADP] ratio. 
A) Fructose 1,6-bisphosphatase is one of the enzymes of the pathway. 
B) It is an endergonic process. 
C) It results in net synthesis of ATP. 
D) It results in synthesis of NADH. 
E) Its rate is slowed by a high [ATP]/[ADP] ratio.

Question 2

Glucose,labeled with 14C in different carbon atoms,is added to a crude extract of a tissue rich in the enzymes of the pentose phosphate pathway.The most rapid production of 14CO2 will occur when the glucose is labeled in:

Accepted Answer

A) C-1. 
B) C-3. 
C) C-4. 
D) C-5. 
E) C-6. 
A) C-1. 
B) C-3. 
C) C-4. 
D) C-5. 
E) C-6.

Question 3

What are the biological functions of the pentose phosphate pathway?

Accepted Answer

The pentose phosphate pathway

Question 4

The ultimate electron acceptor in the fermentation of glucose to ethanol is:

Accepted Answer

A) acetaldehyde. 
B) acetate. 
C) ethanol. 
D) NAD+. 
E) pyruvate. 
A) acetaldehyde. 
B) acetate. 
C) ethanol. 
D) NAD+. 
E) pyruvate.

Question 5

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 6

Which of the following statements 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 7

In glycolysis,fructose 1,6-bisphosphate is converted to two products with a standard free-energy change ($\Delta$G'°)of 23.8 kJ/mol.Under what conditions (encountered in a normal cell)will the free-energy change ($\Delta$G)be negative,enabling the reaction to proceed to the right?

Accepted Answer

A) If the concentrations of the two products are high relative to that of fructose 1,6-bisphosphate. 
B) The reaction will not go to the right spontaneously under any conditions because the $\Delta$G'° is positive. 
C) Under standard conditions,enough energy is released to drive the reaction to the right. 
D) When there is a high concentration of fructose 1,6-bisphosphate relative to the concentration of products. 
E) When there is a high concentration of products relative to the concentration of fructose 1,6-bisphosphate. 
A) If the concentrations of the two products are high relative to that of fructose 1,6-bisphosphate. 
B) The reaction will not go to the right spontaneously under any conditions because the $\Delta$G'° is positive. 
C) Under standard conditions,enough energy is released to drive the reaction to the right. 
D) When there is a high concentration of fructose 1,6-bisphosphate relative to the concentration of products. 
E) When there is a high concentration of products relative to the concentration of fructose 1,6-bisphosphate.

Question 8

Which of the following reactions in glycolysis is a ketose to aldose isomerization?

Accepted Answer

A) Hexokinase 
B) Phosphoglycerate mutase 
C) Enolase 
D) Aldolase 
E) Triose phosphate isomerase 
A) Hexokinase 
B) Phosphoglycerate mutase 
C) Enolase 
D) Aldolase 
E) Triose phosphate isomerase

Question 9

Which of the following reactions in glycolysis requires ATP as a substrate?

Accepted Answer

A) Hexokinase 
B) Glyceraldehyde-3-phosphate dehydrogenase 
C) Pyruvate kinase 
D) Aldolase 
E) Phosphoglycerate kinase 
A) Hexokinase 
B) Glyceraldehyde-3-phosphate dehydrogenase 
C) Pyruvate kinase 
D) Aldolase 
E) Phosphoglycerate kinase

Question 10

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 reaction catalyzed by glyc

Question 11

During strenuous activity,muscle tissue demands large quantities of ATP,compared with resting muscle.In white skeletal muscle (in contrast with red muscle),ATP is produced almost exclusively by fermentation of glucose to lactate.If a person had white muscle tissue devoid of the enzyme lactate dehydrogenase,how would this affect his or her metabolism at rest and during strenuous exercise?

Accepted Answer

Lactate dehydrogenase allows cells to pa

Question 12

Glucose breakdown in certain mammalian and bacterial cells can occur by mechanisms other than classic glycolysis.In most of these,glucose 6-phosphate is oxidized to 6-phosphogluconate,which is then further metabolized by:

Accepted Answer

A) an aldolase-type split to form glyceric acid and glyceraldehyde 3-phosphate. 
B) an aldolase-type split to form glycolic acid and erythrose 4-phosphate. 
C) conversion to 1,6-bisphosphogluconate. 
D) decarboxylation to produce keto- and aldopentoses. 
E) oxidation to a six-carbon dicarboxylic acid. 
A) an aldolase-type split to form glyceric acid and glyceraldehyde 3-phosphate. 
B) an aldolase-type split to form glycolic acid and erythrose 4-phosphate. 
C) conversion to 1,6-bisphosphogluconate. 
D) decarboxylation to produce keto- and aldopentoses. 
E) oxidation to a six-carbon dicarboxylic acid.

Question 13

Which of the following statements about the pentose phosphate pathway is incorrect?

Accepted Answer

A) It generates CO2 from C-1 of glucose. 
B) It involves the conversion of an aldohexose to an aldopentose. 
C) It is prominant in lactating mammary gland. 
D) It is principally directed toward the generation of NADPH. 
E) It requires the participation of molecular oxygen. 
A) It generates CO2 from C-1 of glucose. 
B) It involves the conversion of an aldohexose to an aldopentose. 
C) It is prominant in lactating mammary gland. 
D) It is principally directed toward the generation of NADPH. 
E) It requires the participation of molecular oxygen.

Question 14

All of the intermediated in the glycolytic pathway are phosphorylated.Give two plausible reasons why this might be advantageous to the cell.

Accepted Answer

There are at least three reasons (1)so t

Question 15

Explain why the phosphorolysis of glycogen is more efficient than the hydrolysis of glycogen in mobilizing glucose for the glycolytic pathway.

Accepted Answer

Phosphorolysis yields glucose 1-phosphat

Question 16

Which of the following enzymes acts in the pentose phosphate pathway?

Accepted Answer

A) 6-Phosphogluconate dehydrogenase 
B) Aldolase 
C) Glycogen phosphorylase 
D) Phosphofructokinase-1 
E) Pyruvate kinase 
A) 6-Phosphogluconate dehydrogenase 
B) Aldolase 
C) Glycogen phosphorylase 
D) Phosphofructokinase-1 
E) Pyruvate kinase

Question 17

Which of the following substrates 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 18

Describe the glycolytic pathway from glyceraldehyde 3-phosphate to pyruvate,showing structures of intermediates and names of enzymes.Indicate where any cofactors participate.

Accepted Answer

The answer should show the rea

Question 19

In an anaerobic muscle preparation,lactate formed from glucose labeled in C-2 would be labeled in:

Accepted Answer

A) all three carbon atoms. 
B) only the carbon atom carrying the OH. 
C) only the carboxyl carbon atom. 
D) only the methyl carbon atom. 
E) the methyl and carboxyl carbon atoms. 
A) all three carbon atoms. 
B) only the carbon atom carrying the OH. 
C) only the carboxyl carbon atom. 
D) only the methyl carbon atom. 
E) the methyl and carboxyl carbon atoms.

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

Which of the following statements is not true concerning glycolysis in anaerobic muscle?

Glucose,labeled with 14C in different carbon atoms,is added to a crude extract of a tissue rich in the enzymes of the pentose phosphate pathway.The most rapid production of 14CO2 will occur when the glucose is labeled in:

What are the biological functions of the pentose phosphate pathway?

The ultimate electron acceptor in the fermentation of glucose to ethanol is:

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:

Which of the following statements is incorrect?

In glycolysis,fructose 1,6-bisphosphate is converted to two products with a standard free-energy change ( Δ\DeltaΔ G'°)of 23.8 kJ/mol.Under what conditions (encountered in a normal cell)will the free-energy change ( Δ\DeltaΔ G)be negative,enabling the reaction to proceed to the right?

Which of the following reactions in glycolysis is a ketose to aldose isomerization?

Which of the following reactions in glycolysis requires ATP as a substrate?

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.

Glucose breakdown in certain mammalian and bacterial cells can occur by mechanisms other than classic glycolysis.In most of these,glucose 6-phosphate is oxidized to 6-phosphogluconate,which is then further metabolized by:

Which of the following statements about the pentose phosphate pathway is incorrect?

All of the intermediated in the glycolytic pathway are phosphorylated.Give two plausible reasons why this might be advantageous to the cell.

Explain why the phosphorolysis of glycogen is more efficient than the hydrolysis of glycogen in mobilizing glucose for the glycolytic pathway.

Which of the following enzymes acts in the pentose phosphate pathway?

Which of the following substrates cannot contribute to net gluconeogenesis in mammalian liver?

Describe the glycolytic pathway from glyceraldehyde 3-phosphate to pyruvate,showing structures of intermediates and names of enzymes.Indicate where any cofactors participate.

In an anaerobic muscle preparation,lactate formed from glucose labeled in C-2 would be labeled in:

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

Recombinant Dna Technology

Lipids

Biological Membranes and Transport

Biosignaling

Principles of Bioenergetics

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

Integration and Hormonal Regulation of Mammalian Metabolism

Genes and Chromosomes

Dna Metabolism

Rna Metabolism

Protein Metabolism

Regulation of Gene Expression

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Glucose,labeled with ¹⁴C in different carbon atoms,is added to a crude extract of a tissue rich in the enzymes of the pentose phosphate pathway.The most rapid production of ¹⁴CO₂ will occur when the glucose is labeled in:

In glycolysis,fructose 1,6-bisphosphate is converted to two products with a standard free-energy change ( $\Delta$ G'°)of 23.8 kJ/mol.Under what conditions (encountered in a normal cell)will the free-energy change ( $\Delta$ G)be negative,enabling the reaction to proceed to the right?

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.