Question 1

Complete oxidation of 1 mole of which fatty acid would yield the most ATP?

Accepted Answer

A) 16-carbon saturated fatty acid 
B) 18-carbon mono-unsaturated fatty acid 
C) 16-carbon mono-unsaturated fatty acid 
D) 16-carbon poly-unsaturated fatty acid 
E) 14-carbon saturated fatty acid 
A) 16-carbon saturated fatty acid 
B) 18-carbon mono-unsaturated fatty acid 
C) 16-carbon mono-unsaturated fatty acid 
D) 16-carbon poly-unsaturated fatty acid 
E) 14-carbon saturated fatty acid B

Question 2

Explain the chemical reason why the addition of water across the double bond in the second step of $\beta$-oxidation occurs with the OH adding at the $\beta$-carbon,not the $\alpha$-carbon.Also,how does addition at the $\beta$-carbon aid in the subsequent step(s)of $\beta$-oxidation?

Accepted Answer

Recall that the carbon that is $\alpha$ to a carbonyl is readily able to become a carbanion;i.e.it is not a good electrophilic center for nucleophilic addition of a hydroxide (see Chapter 13).The $\beta$-carbon,by contrast is a good electrophilic center as can be readily shown by "pushing" the electrons from the C=C double bond onto the carbonyl oxygen.Addition of the OH in the $\beta$-position is useful for later steps since after oxidation of the OH to a carbonyl,the $\alpha$-carbon is even more susceptible to becoming a carbanion,as is needed for the reverse Claisen condensation catalyzed by thiolase.

Question 3

The total degradation of a fatty acid with an odd number of carbons yields acetyl-CoA and another compound,X.Show the structure of X and describe the pathway by which it is converted into a citric acid cycle intermediate,including where any cofactors participate.

Accepted Answer

X is propionyl-CoA, and its conversion into succinyl-CoA is accomplished by the reactions in Fig. 17-12.

Question 4

Which of the following is (are) true of the oxidation of 1 mol of palmitate (a 16-carbon saturated fatty acid; 16:0) by the β-oxidation pathway, beginning with the free fatty acid in the cytoplasm?
1. Activation of the free fatty acid requires the equivalent of two ATPs.
2. Inorganic pyrophosphate (PPi) is produced.
3. Carnitine functions as an electron acceptor.
4. 8 mol of FADH2 are formed.
5. 8 mol of acetyl-CoA are formed.
6. There is no direct involvement of NAD+.

Accepted Answer

A) 1 and 5 only 
B) 1,2,and 5 
C) 1,2,and 6 
D) 1,3,and 5 
E) 5 only 
A) 1 and 5 only 
B) 1,2,and 5 
C) 1,2,and 6 
D) 1,3,and 5 
E) 5 only

Question 5

Which of the following statements apply (applies) to the β-oxidation of fatty acids? 
1.  The process takes place in the cytosol of mammalian cells.
2.  Carbon atoms are removed from the acyl chain one at a time.
3.  Before oxidation, fatty acids must be converted to their CoA derivatives.
4.  NADP+ is the electron acceptor.
5.  The products of β-oxidation can directly enter the citric acid cycle for further oxidation.

Accepted Answer

A) 1 and 3 only 
B) 1,2,and 3 
C) 1,2,and 5 
D) 3 and 5 only 
E) 4 only 
A) 1 and 3 only 
B) 1,2,and 3 
C) 1,2,and 5 
D) 3 and 5 only 
E) 4 only

Question 6

Free fatty acids in the bloodstream are:

Accepted Answer

A) bound to hemoglobin. 
B) carried by the protein serum albumin. 
C) freely soluble in the aqueous phase of the blood. 
D) nonexistent;the blood does not contain free fatty acids. 
E) present at levels that are independent of epinephrine. 
A) bound to hemoglobin. 
B) carried by the protein serum albumin. 
C) freely soluble in the aqueous phase of the blood. 
D) nonexistent;the blood does not contain free fatty acids. 
E) present at levels that are independent of epinephrine.

Question 7

When comparing the $\beta$-oxidation and  $ \omega $-oxidation pathways,which one of the following statements is correct?

Accepted Answer

A) ($\beta$-oxidation and  $ \omega $-oxidation occur in the cytoplasm.) 
B) ($\beta$-oxidation occurs at the carboxyl end of the fatty acid whereas  $ \omega $ oxidation occurs at the methyl end.) 
C) ($\beta$-oxidation occurs at the methyl end of the fatty acid,whereas  $ \omega $-oxidation occurs at the carboxyl end.) 
D) ($\beta$-oxidation occurs mainly in the cytoplasm,whereas  $ \omega $-oxidation occurs mainly in the mitochondria.) 
E) ($\beta$-oxidation occurs mainly in the mitochondria,whereas  $ \omega $-oxidation occurs mainly in the cytoplasm.) 
A) ($\beta$-oxidation and  $ \omega $-oxidation occur in the cytoplasm.) 
B) ($\beta$-oxidation occurs at the carboxyl end of the fatty acid whereas  $ \omega $ oxidation occurs at the methyl end.) 
C) ($\beta$-oxidation occurs at the methyl end of the fatty acid,whereas  $ \omega $-oxidation occurs at the carboxyl end.) 
D) ($\beta$-oxidation occurs mainly in the cytoplasm,whereas  $ \omega $-oxidation occurs mainly in the mitochondria.) 
E) ($\beta$-oxidation occurs mainly in the mitochondria,whereas  $ \omega $-oxidation occurs mainly in the cytoplasm.)

Question 8

In the disease sprue,vitamin B12 (cobalamin)is poorly absorbed in the intestine,resulting in B12 deficiency.If each of the following fatty acids were in the diet,for which one would the process of fatty acid oxidation be most affected in a patient with sprue?

Accepted Answer

A) CH3(CH2)10COOH 
B) CH3(CH2)11COOH 
C) CH3(CH2)12COOH 
D) CH3(CH2)14COOH 
E) CH3(CH2)18COOH 
A) CH3(CH2)10COOH 
B) CH3(CH2)11COOH 
C) CH3(CH2)12COOH 
D) CH3(CH2)14COOH 
E) CH3(CH2)18COOH

Question 9

Describe the steps in the metabolic pathway in which cells oxidize a four-carbon,straight-chain,saturated fatty acid (butyrate;4:0)to the fragments that enter the citric acid cycle.Show the structures of intermediates and products,and indicate where any cofactor(s)participate(s).

Accepted Answer

Butyrate is first activated:
Butyrate +

Question 10

The carbon atoms from a fatty acid with an odd number of carbons will enter the citric acid cycle as acetyl-CoA and:

Accepted Answer

A) butyrate. 
B) citrate. 
C) malate. 
D) succinyl-CoA. 
E) ($\alpha$-ketoglutarate.) 
A) butyrate. 
B) citrate. 
C) malate. 
D) succinyl-CoA. 
E) ($\alpha$-ketoglutarate.)

Question 11

In the first step of fatty acid oxidation,the fatty acid (R-COOH)is converted to its coenzyme A derivative in the following reaction:
R-COOH + ATP + CoA-SH $\rightarrow$ R-CO-S-CoA + AMP + PPi
The standard free-energy change ($\Delta$G'° )for this reaction is -15 kJ/mol
What will tend to make the reaction even more favorable when it takes place within a cell?

Accepted Answer

The hydrolysis of PP_i

Question 12

Saturated fatty acids are degraded by the stepwise reactions of $\beta$-oxidation,producing acetyl-CoA.Under aerobic conditions,how many ATP molecules would be produced as a consequence of removal of each acetyl-CoA?

Accepted Answer

A) 2 
B) 3 
C) 4 
D) 5 
E) 6 
A) 2 
B) 3 
C) 4 
D) 5 
E) 6

Question 13

Draw the structure of one ketone body,and describe circumstances under which you would expect to find high concentrations of this compound in the urine of a human.

Accepted Answer

The ketone bodies,acetoacetate

Question 14

Ketone bodies are formed in the liver and transported to the extrahepatic tissues mainly as:

Accepted Answer

A) acetoacetyl-CoA. 
B) acetone. 
C) ($\beta$-hydroxybutyric acid.) 
D) ($\beta$-hydroxybutyryl-CoA.) 
E) lactic acid. 
A) acetoacetyl-CoA. 
B) acetone. 
C) ($\beta$-hydroxybutyric acid.) 
D) ($\beta$-hydroxybutyryl-CoA.) 
E) lactic acid.

Question 15

An experimenter studying the oxidation of fatty acids in extracts of liver found that when palmitate (16:0)was provided as substrate,it was completely oxidized to CO2.However,when undecanoic acid (11:0)was added as substrate,incomplete oxidation occurred unless he bubbled CO2 through the reaction mixture.The addition of the protein avidin,which binds tightly to biotin,prevented the complete oxidation of undecanoic acid even in the presence of CO2,although it had no effect on palmitate oxidation.Explain these observations in light of what you know of fatty acid oxidation reactions.

Accepted Answer

Oxidation of odd-chain fatty acid yields

Question 16

The role of hormone-sensitive triacylglycerol lipase is to:

Accepted Answer

A) hydrolyze lipids stored in the liver. 
B) hydrolyze membrane phospholipids in hormone-producing cells. 
C) hydrolyze triacylglycerols stored in adipose tissue. 
D) synthesize lipids in adipose tissue. 
E) synthesize triacylglycerols in the liver. 
A) hydrolyze lipids stored in the liver. 
B) hydrolyze membrane phospholipids in hormone-producing cells. 
C) hydrolyze triacylglycerols stored in adipose tissue. 
D) synthesize lipids in adipose tissue. 
E) synthesize triacylglycerols in the liver.

Question 17

The following fatty acid,in which the indicated carbon is labeled with 14C,is fed to an animal: 14CH3(CH2)9COOH
After allowing 30 minutes for fatty acid $\beta$-oxidation,the label would most likely be recovered in:

Accepted Answer

A) acetyl-CoA. 
B) beta-hydroxy butyryl-CoA. 
C) both acetyl-CoA and propionyl-CoA. 
D) palmitoyl-CoA. 
E) propionyl-CoA. 
A) acetyl-CoA. 
B) beta-hydroxy butyryl-CoA. 
C) both acetyl-CoA and propionyl-CoA. 
D) palmitoyl-CoA. 
E) propionyl-CoA.

Question 18

Which compound is an intermediate of the $\beta$-oxidation of fatty acids?

Accepted Answer

A) CH3-(CH2)20-CO-COOH 
B) CH3-CH2-CO-CH2-CO-OPO32-  
C) CH3-CH2-CO-CH2-OH 
D) CH3-CH2-CO-CO-S-CoA 
E) CH3-CO-CH2-CO-S-CoA 
A) CH3-(CH2)20-CO-COOH 
B) CH3-CH2-CO-CH2-CO-OPO32-  
C) CH3-CH2-CO-CH2-OH 
D) CH3-CH2-CO-CO-S-CoA 
E) CH3-CO-CH2-CO-S-CoA

Question 19

If an aerobic organism (e.g. ,the bacterium E.coli)were fed each of the following four compounds as a source of energy,the energy yield per mole from these molecules would be in the order:

Accepted Answer

A) alanine > glucose > palmitate 
B) glucose > alanine > palmitate 
C) glucose > palmitate > alanine 
D) palmitate > alanine > glucose 
E) palmitate > glucose > alanine 
A) alanine > glucose > palmitate 
B) glucose > alanine > palmitate 
C) glucose > palmitate > alanine 
D) palmitate > alanine > glucose 
E) palmitate > glucose > alanine

Question 20

Carnitine is:

Accepted Answer

A) a 15-carbon fatty acid. 
B) an essential cofactor for the citric acid cycle. 
C) essential for intracellular transport of fatty acids. 
D) one of the amino acids commonly found in protein. 
E) present only in carnivorous animals. 
A) a 15-carbon fatty acid. 
B) an essential cofactor for the citric acid cycle. 
C) essential for intracellular transport of fatty acids. 
D) one of the amino acids commonly found in protein. 
E) present only in carnivorous animals.

Exam 17: Fatty Acid Catabolism

Complete oxidation of 1 mole of which fatty acid would yield the most ATP?

Explain the chemical reason why the addition of water across the double bond in the second step of β\betaβ -oxidation occurs with the OH adding at the β\betaβ -carbon,not the α\alphaα -carbon.Also,how does addition at the β\betaβ -carbon aid in the subsequent step(s)of β\betaβ -oxidation?

The total degradation of a fatty acid with an odd number of carbons yields acetyl-CoA and another compound,X.Show the structure of X and describe the pathway by which it is converted into a citric acid cycle intermediate,including where any cofactors participate.

Free fatty acids in the bloodstream are:

When comparing the β\betaβ -oxidation and ω \omega ω -oxidation pathways,which one of the following statements is correct?

In the disease sprue,vitamin B12 (cobalamin)is poorly absorbed in the intestine,resulting in B12 deficiency.If each of the following fatty acids were in the diet,for which one would the process of fatty acid oxidation be most affected in a patient with sprue?

Describe the steps in the metabolic pathway in which cells oxidize a four-carbon,straight-chain,saturated fatty acid (butyrate;4:0)to the fragments that enter the citric acid cycle.Show the structures of intermediates and products,and indicate where any cofactor(s)participate(s).

The carbon atoms from a fatty acid with an odd number of carbons will enter the citric acid cycle as acetyl-CoA and:

Saturated fatty acids are degraded by the stepwise reactions of β\betaβ -oxidation,producing acetyl-CoA.Under aerobic conditions,how many ATP molecules would be produced as a consequence of removal of each acetyl-CoA?

Draw the structure of one ketone body,and describe circumstances under which you would expect to find high concentrations of this compound in the urine of a human.

Ketone bodies are formed in the liver and transported to the extrahepatic tissues mainly as:

The role of hormone-sensitive triacylglycerol lipase is to:

The following fatty acid,in which the indicated carbon is labeled with 14C,is fed to an animal: 14CH3(CH2)9COOH After allowing 30 minutes for fatty acid β\betaβ -oxidation,the label would most likely be recovered in:

Which compound is an intermediate of the β\betaβ -oxidation of fatty acids?

If an aerobic organism (e.g. ,the bacterium E.coli)were fed each of the following four compounds as a source of energy,the energy yield per mole from these molecules would be in the order:

Carnitine is:

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

Glycolysis, gluconeogenesis, and the Pentose Phosphate Pathway

Principles of Metabolic Regulation

The Citric Acid Cycle

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

Explain the chemical reason why the addition of water across the double bond in the second step of $\beta$ -oxidation occurs with the OH adding at the $\beta$ -carbon,not the $\alpha$ -carbon.Also,how does addition at the $\beta$ -carbon aid in the subsequent step(s)of $\beta$ -oxidation?

When comparing the $\beta$ -oxidation and $\omega$ -oxidation pathways,which one of the following statements is correct?

In the disease sprue,vitamin B₁₂ (cobalamin)is poorly absorbed in the intestine,resulting in B₁₂ deficiency.If each of the following fatty acids were in the diet,for which one would the process of fatty acid oxidation be most affected in a patient with sprue?

Saturated fatty acids are degraded by the stepwise reactions of $\beta$ -oxidation,producing acetyl-CoA.Under aerobic conditions,how many ATP molecules would be produced as a consequence of removal of each acetyl-CoA?

The following fatty acid,in which the indicated carbon is labeled with ¹⁴C,is fed to an animal: ¹⁴CH₃(CH₂)₉COOH After allowing 30 minutes for fatty acid $\beta$ -oxidation,the label would most likely be recovered in:

Which compound is an intermediate of the $\beta$ -oxidation of fatty acids?