Question 1

An enzyme used in both glycolysis and gluconeogenesis is:

Accepted Answer

A) 3-phosphoglycerate kinase. 
B) glucose 6-phosphatase. 
C) hexokinase. 
D) phosphofructokinase-1. 
E) pyruvate kinase. 
A) 3-phosphoglycerate kinase. 
B) glucose 6-phosphatase. 
C) hexokinase. 
D) phosphofructokinase-1. 
E) pyruvate kinase.

Question 2

Define "fermentation" and explain,by describing relevant reactions,how it differs from glycolysis.Your explanation should include a discussion of the role of NADH in the reaction(s).

Accepted Answer

Fermentation is the operation of the gly

Question 3

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

Accepted Answer

In lactose intolerance,the enzyme lactas

Question 4

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

Question 5

Rat liver is able to metabolize glucose by both the glycolytic and the pentose phosphate pathways.Indicate in the blanks if the following are properties of glycolytic (G),pentose phosphate (P),both (G + P),or neither (0):
_____ NAD+ is involved.
_____ CO2 is liberated.
_____ Phosphate esters are intermediates.
_____ Glyceraldehyde 3-phosphate is an intermediate.
_____ Fructose 6-phosphate is an intermediate.

Accepted Answer

Question 6

Two reactions in glycolysis produce ATP.For each of these,show the name and structure of reactant and product,indicate which cofactors participate and where,and name the enzymes.

Accepted Answer

The two reactions ar

Question 7

Yeast can metabolize D-mannose to ethanol and CO2.In addition to the glycolytic enzymes,the only other enzyme needed is phosphomannose isomerase,which converts mannose 6-phosphate to fructose 6-phosphate.If mannose is converted to ethanol and CO2 by the most direct pathway,which of the compounds and cofactors in this list are involved?

Accepted Answer

A) Lactate 
B) Acetaldehyde 
C) Acetyl-CoA 
D) FAD 
E) Glucose 6-phosphate
F)Fructose 1-phosphate
G)Pyruvate
H)Lipoic acid
I)Thiamine pyrophosphate
J)Dihydroxyacetone phosphate 
A) Lactate 
B) Acetaldehyde 
C) Acetyl-CoA 
D) FAD 
E) Glucose 6-phosphate
F)Fructose 1-phosphate
G)Pyruvate
H)Lipoic acid
I)Thiamine pyrophosphate
J)Dihydroxyacetone phosphate

Question 8

Which of the following compounds cannot serve as the starting material for the synthesis of glucose via gluconeogenesis?

Accepted Answer

A) acetate 
B) glycerol 
C) lactate 
D) oxaloacetate 
E) ($\alpha$-ketoglutarate) 
A) acetate 
B) glycerol 
C) lactate 
D) oxaloacetate 
E) ($\alpha$-ketoglutarate)

Question 9

Show how NADH is recycled to NAD+ under aerobic conditions and under anaerobic conditions.Why is it important to recycle NADH produced during glycolysis to NAD+?

Accepted Answer

Cells contain a limited supply of NAD⁺ an

Question 10

When glucose labeled with a 14C at C-1 (the aldehyde carbon)passes through glycolysis,the glyceraldehyde 3-phosphate that is produced from it still contains the radioactive carbon atom.Draw the structure of glyceraldehyde 3-phosphate,and circle the atom(s)that would be radioactive.

Accepted Answer

The labele

Question 11

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

Accepted Answer

A) Enolase 
B) Phosphoglycerate mutase 
C) Phosphohexose isomerase 
D) Aldolase 
E) Glyceraldehyde-3-phosphate dehydrogenase 
A) Enolase 
B) Phosphoglycerate mutase 
C) Phosphohexose isomerase 
D) Aldolase 
E) Glyceraldehyde-3-phosphate dehydrogenase

Question 12

Which of the following reactions in glycolysis produces ATP as a product?

Accepted Answer

A) Hexokinase 
B) Glyceraldehyde-3-phosphate dehydrogenase 
C) Pyruvate kinase 
D) Aldolase 
E) Phosphofructokinase-1 
A) Hexokinase 
B) Glyceraldehyde-3-phosphate dehydrogenase 
C) Pyruvate kinase 
D) Aldolase 
E) Phosphofructokinase-1

Question 13

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

Muscle glycogen consists of linear polym

Question 14

In an anaerobic muscle preparation,lactate formed from glucose labeled in C-3 and C-4 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.

Question 15

All of the following enzymes involved in the flow of carbon from glucose to lactate (glycolysis)are also involved in the reversal of this flow (gluconeogenesis)except:

Accepted Answer

A) 3-phosphoglycerate kinase. 
B) aldolase. 
C) enolase. 
D) phosphofructokinase-1. 
E) phosphoglucoisomerase. 
A) 3-phosphoglycerate kinase. 
B) aldolase. 
C) enolase. 
D) phosphofructokinase-1. 
E) phosphoglucoisomerase.

Question 16

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

Accepted Answer

A) It generates 36 mol of ATP per mole of glucose consumed. 
B) It generates 6 moles of CO2 for each mole of glucose consumed 
C) It is a reductive pathway;it consumes NADH. 
D) It is present in plants,but not in animals. 
E) It provides precursors for the synthesis of nucleotides. 
A) It generates 36 mol of ATP per mole of glucose consumed. 
B) It generates 6 moles of CO2 for each mole of glucose consumed 
C) It is a reductive pathway;it consumes NADH. 
D) It is present in plants,but not in animals. 
E) It provides precursors for the synthesis of nucleotides.

Question 17

If glucose labeled with 14C in C-1 were fed to yeast carrying out the ethanol fermentation,where would the 14C label be in the products?

Accepted Answer

A) In C-1 of ethanol and CO2  
B) In C-1 of ethanol only 
C) In C-2 (methyl group)of ethanol only 
D) In C-2 of ethanol and CO2 
E) In CO2 only 
A) In C-1 of ethanol and CO2  
B) In C-1 of ethanol only 
C) In C-2 (methyl group)of ethanol only 
D) In C-2 of ethanol and CO2 
E) In CO2 only

Question 18

In the phosphoglycerate mutase reaction,the side chain of which amino acid in the enzyme is transiently phosphorylated as part of the reaction?

Accepted Answer

A) Serine 
B) Threonine 
C) Tyrosine 
D) Histidine 
E) Arginine 
A) Serine 
B) Threonine 
C) Tyrosine 
D) Histidine 
E) Arginine

Question 19

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

Accepted Answer

Inorganic phosphate (P_i)is an e

Question 20

The bacterium E.coli can grow in a medium in which the only carbon source is glucose.How does this organism obtain ribose 5-phosphate for the synthesis of ATP? (Do not describe ATP synthesis,just the origin of ribose 5-phosphate. )Show structures and indicate where cofactors participate.

Accepted Answer

Ribose 5-phosphate i

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

An enzyme used in both glycolysis and gluconeogenesis is:

Define "fermentation" and explain,by describing relevant reactions,how it differs from glycolysis.Your explanation should include a discussion of the role of NADH in the reaction(s).

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

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

Two reactions in glycolysis produce ATP.For each of these,show the name and structure of reactant and product,indicate which cofactors participate and where,and name the enzymes.

Which of the following compounds cannot serve as the starting material for the synthesis of glucose via gluconeogenesis?

Show how NADH is recycled to NAD+ under aerobic conditions and under anaerobic conditions.Why is it important to recycle NADH produced during glycolysis to NAD+?

When glucose labeled with a 14C at C-1 (the aldehyde carbon)passes through glycolysis,the glyceraldehyde 3-phosphate that is produced from it still contains the radioactive carbon atom.Draw the structure of glyceraldehyde 3-phosphate,and circle the atom(s)that would be radioactive.

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

Which of the following reactions in glycolysis produces ATP as a product?

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).

In an anaerobic muscle preparation,lactate formed from glucose labeled in C-3 and C-4 would be labeled in:

All of the following enzymes involved in the flow of carbon from glucose to lactate (glycolysis)are also involved in the reversal of this flow (gluconeogenesis)except:

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

If glucose labeled with 14C in C-1 were fed to yeast carrying out the ethanol fermentation,where would the 14C label be in the products?

In the phosphoglycerate mutase reaction,the side chain of which amino acid in the enzyme is transiently phosphorylated as part of the reaction?

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

The bacterium E.coli can grow in a medium in which the only carbon source is glucose.How does this organism obtain ribose 5-phosphate for the synthesis of ATP? (Do not describe ATP synthesis,just the origin of ribose 5-phosphate. )Show structures and indicate where cofactors participate.

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

Filters

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

Show how NADH is recycled to NAD⁺ under aerobic conditions and under anaerobic conditions.Why is it important to recycle NADH produced during glycolysis to NAD⁺?

When glucose labeled with a ¹⁴C at C-1 (the aldehyde carbon)passes through glycolysis,the glyceraldehyde 3-phosphate that is produced from it still contains the radioactive carbon atom.Draw the structure of glyceraldehyde 3-phosphate,and circle the atom(s)that would be radioactive.

If glucose labeled with ¹⁴C in C-1 were fed to yeast carrying out the ethanol fermentation,where would the ¹⁴C label be in the products?

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