Deck 17: The Organic Chemistry of Metabolic Pathways

Question 1

Consider the deamination of serine to answer the following questions.
a)Draw the structure of the $\alpha$ -keto acid produced by the deamination of serine.
b)What is the fate of the amino group in serine when this conversion occurs in a mammalian system?

Answer 1

a)
b)The amino group is removed in the deamination as ammonia. The ammonia is in turn converted into urea and excreted during the urea cycle.

Question 2

The reaction of fructose 1,6-bisphosphate to give glyceraldehyde-3-phosphate and dihydroxyacetone phosphate is an example of

A) a reverse aldol condensation
B) hydrolysis
C) oxidation
D) dehydration

Answer 2

a reverse aldol condensation

Question 3

A coenzyme frequently encountered in transamination reactions is

A) tetrahydrofolate
B) pyridoxal phosphate
C) thiamine pyrophosphate
D) biotin

Answer 3

pyridoxal phosphate

Question 4

Which group of small molecules best fit the boxes associated with the reaction shown?

Question 5

Consider the structure of amylopectin below to answer the following questions. a)Circle the glycosidic links that are hydrolyzed in the small intestine.
b)What is the final product of complete hydrolysis of amylpectin?

Question 6

Instructions: Consider the reaction below to answer the following question(s).
Refer to instructions. Write the mechanism for this isomerization.

Question 7

Many biological reactions are endergonic. Explain how it is possible that these reactions occur spontaneously.

Question 8

During the complete catabolism of a molecule of glucose, the ultimate fate of the carbon atoms are

A) pyruvate
B) AcetylCoA
C) carbon dioxide
D) fructose-6-phosphate
E) a, b or c

Question 9

Which enzyme catalyzes the reaction shown?

A) an epimerase
B) an isomerase
C) a mutase
D) a dehydrogenase

Question 10

The key functional group in the PLP-dependent transamination of an $\alpha$ -amino acid is an activated

A) amine
B) imine
C) amide
D) enamine

Question 11

The formation of amino acids from proteins

A) occurs during anabolism.
B) is endergonic.
C) occurs during digestion.
D) is a cellular process.
E) all of these

Question 12

Instructions: Consider the reaction below to answer the following question(s).
Refer to instructions. This reaction proceeds through a common enol structure. Draw the structure of the glucose/fructose enol.

Question 13

Which group of small molecules best fit the boxes associated with the reaction shown?

Question 14

What reaction does glutamate dehydrogenase (GDH) catalyze?

A) The oxidative deamination of glutamate to yield $\alpha$ -ketoglutarate.
B) Phosphorylation of carbamate to yield carbamoyl phosphate.
C) The amidation of the $\gamma$ carboxyl group of glutamate to form glutamine.
D) The deadenylation of glutamine synthetase (GS).
E) The adenylation of glutamine synthetase.

Question 15

What product would be obtained from enzymatic transamination of 3-hydroxy-2-ketopropanoic acid?

Question 16

Consider the following reaction. Which of the following describes this reaction?

A) is so strongly exergonic that it does not require a catalyst
B) is an exergonic reaction not coupled to any other reaction
C) is an endergonic reaction that takes place because it is coupled to the exergonic hydrolysis of ATP
D) is an exergonic reaction that is coupled to the endergonic hydrolysis of ATP

Question 17

When acetyl-CoA reacts with oxaloacetate to form citrate

A) a new carbon-carbon bond is formed
B) an oxidative decarboxylation reaction takes place
C) a dehydration reaction takes place
D) a rearrangement takes place

Question 18

Which group of small molecules best fit the boxes associated with the reaction shown?

Question 19

Which group of small molecules best fit the boxes associated with the reaction shown?

Question 20

What amino acid is the following $\alpha$ -keto acid derived from?

Question 21

The source of oxygen for $\beta$ -oxidation is:

A) CO₂
B) O₂
C) Peroxide
D) Water
E) None of these is the source of oxygen for $\beta$ -oxidation.

Question 22

Instructions: Match a term or structure from the list below to each of the following definitions or names.

The product of the citric acid cycle, which is a reactant in the first step.

A)electron-transport chain
B)
C)citric acid cycle
D)Embden-Meyerhoff
E)glycolysis
F)
G)Hans Krebs
H)catabolism
I)ATP
J)
K)anabolism
L)acetyl CoA
M)
N)metabolism
O)

Question 23

Instructions: Match a term or structure from the list below to each of the following definitions or names.

The "energy currency" of the cell.

A)electron-transport chain
B)
C)citric acid cycle
D)Embden-Meyerhoff
E)glycolysis
F)
G)Hans Krebs
H)catabolism
I)ATP
J)
K)anabolism
L)acetyl CoA
M)
N)metabolism
O)

Question 24

Instructions: Match a term or structure from the list below to each of the following definitions or names.

Pathways that break down larger biomolecules into smaller ones.

A)electron-transport chain
B)
C)citric acid cycle
D)Embden-Meyerhoff
E)glycolysis
F)
G)Hans Krebs
H)catabolism
I)ATP
J)
K)anabolism
L)acetyl CoA
M)
N)metabolism
O)

Question 25

Instructions: Match a term or structure from the list below to each of the following definitions or names.

Reactions that put smaller molecules together to synthesize larger biomolecules.

A)electron-transport chain
B)
C)citric acid cycle
D)Embden-Meyerhoff
E)glycolysis
F)
G)Hans Krebs
H)catabolism
I)ATP
J)
K)anabolism
L)acetyl CoA
M)
N)metabolism
O)

Question 26

All of the following are byproducts of $\beta$ -oxidation, except:

A) Acetyl CoA
B) ADP
C) NADH
D) FADH₂
E) All of these are byproducts of $\beta$ -oxidation.

Question 27

Instructions: Match a term or structure from the list below to each of the following definitions or names.

Acetyl groups are oxidized to yield carbon dioxide and water.

A)electron-transport chain
B)
C)citric acid cycle
D)Embden-Meyerhoff
E)glycolysis
F)
G)Hans Krebs
H)catabolism
I)ATP
J)
K)anabolism
L)acetyl CoA
M)
N)metabolism
O)

Question 28

What is the structure of the $\alpha$ -keto acid formed by transamination of the amino acid isoleucine?

Question 29

Draw the structure of the ultimate organic glycolysis product of $\alpha$ -glucose.

Question 30

Instructions: Consider the reaction below to answer the following questions:

Refer to instructions. Draw arrows on the structure below showing electron flow in this reaction.

Question 31

How many molecules of acetyl CoA are produced in the catabolism of stearic acid?

Question 32

Draw and name the major product of the reaction of $\alpha$ -glucose with ATP.

Question 33

Instructions: Consider the reaction below to answer the following questions:

Refer to instructions. This reaction is an example of:

A) an aldol reaction
B) a Claisen reaction
C) a reverse Claisen reaction
D) a reto aldol reaction

Question 34

Instructions: Match a term or structure from the list below to each of the following definitions or names.

Discoverer of the glycolysis pathway.

A)electron-transport chain
B)
C)citric acid cycle
D)Embden-Meyerhoff
E)glycolysis
F)
G)Hans Krebs
H)catabolism
I)ATP
J)
K)anabolism
L)acetyl CoA
M)
N)metabolism
O)

Question 35

Instructions: Match a term or structure from the list below to each of the following definitions or names.

Pyridoxal phosphate, the cofactor in transaminations.

A)electron-transport chain
B)
C)citric acid cycle
D)Embden-Meyerhoff
E)glycolysis
F)
G)Hans Krebs
H)catabolism
I)ATP
J)
K)anabolism
L)acetyl CoA
M)
N)metabolism
O)

Question 36

How many passages through the $\beta$ -oxidation pathway are required to completely degrade the following fatty acid?
CH₃(CH₂)₁₂CO₂H

Question 37

Instructions: Match a term or structure from the list below to each of the following definitions or names.


-Coenzyme NAD⁺ required in the $\beta$ -oxidation of fatty acids, glycolysis, and the citric acid cycle.

A)electron-transport chain
B)
C)citric acid cycle
D)Embden-Meyerhoff
E)glycolysis
F)
G)Hans Krebs
H)catabolism
I)ATP
J)
K)anabolism
L)acetyl CoA
M)
N)metabolism
O)

Question 38

All of the following describe $\beta$ -oxidation, except:

A) Two-carbon units are eliminated during each cycle.
B) The process employs NAD⁺ as an oxidant.
C) The process is the primary route to fatty acid degradation.
D) The 2-carbon groups are eliminated from the methyl end of the fatty acid.
E) Fatty acids are attached to coenzyme A during the process.

Question 39

Draw the product of the following reaction, which is involved in the catabolism of triacylglycerols.

Question 40

Instructions: Consider the reaction below to answer the following question(s).
Refer to instructions. The isomerization of glucose 6-phosphate to fructose 6-phosphate is an example of:

A) an elimination reaction
B) an oxidation reaction
C) keto-enol tautomerism
D) a conjugate addition reaction