Deck 22: Fatty Acid Catabolism

Question 1

The first oxidation in the b-oxidation of saturated fatty acids is catalyzed by acyl-CoA dehydrogenase.Which of the following chemical conversions does it catalyze?

A)a primary alcohol to an aldehyde
B)a carbon-carbon single bond to a carbon-carbon double bond
C)a secondary alcohol to a ketone
D)an aldehyde to a carboxylic acid

Answer 1

B

Question 2

Which of the following steps is NOT a part of the sequence of events for activation of the release of fatty acids from adipose cells?

A)triacylglycerol lipase inactivation
B)adenylyl cyclase activation
C)cAMP production
D)hormone binding to the receptor

Answer 2

A

Question 3

Which of the following sequences of metabolic reactions is analogous to the first 3 reactions of ?-oxidation of saturated fatty acids?

A)succinate? fumarate ?malate ?oxaloacetate
B)isocitrate ? ?-ketoglutarat?e succinate ? fumarate
C)oxaloacetate ?citrate? isocitrate ? ?-ketoglutarate
D)phosphoenolpyruvate? pyruvate? acetyl-CoA? citrate

Answer 3

succinate? fumarate ?malate ?oxaloacetate

Question 4

Which of the following is NOT a use for acetyl-CoA,a product of b-oxidation?

A)synthesis of ketone bodies
B)synthesis of amino acids
C)catabolism in the TCA cycle
D)synthesis of glucose

Question 5

Absorbed lipids are condensed with glycerol in the epithelial cells to make triacylglycerols.Which of the following lipid particles are they repackaged into,and then transported by the lymphatic system?

A)VLDLs
B)HDLs
C)LDLs
D)chylomicrons

Question 6

Which of the following citric acid cycle enzymes is L-hydroxyacyl-CoA dehydrogenase analogous to?

A)malate dehydrogenase
B)citrate synthase
C)isocitrate dehydrogenase
D)a-ketoglutarate dehydrogenase

Question 7

Which of the following is NOT a feature of acyl-CoA dehydrogenase?

A)The Ca-Cb bond is reduced.
B)It comes in at least 3 isozymes,each specific for fatty acids of differing chain lengths.
C)It uses tightly bound FAD.
D)Electrons are transferred to electron transfer flavoprotein (ETF)and on to Q of the electron transport system.

Question 8

How many NADH are generated from the complete oxidation of palmitoyl-CoA to CO₂?

A)21 by TCA plus 7 by b-oxidation
B)24 by TCA plus 7 by b-oxidation
C)24 by TCA plus 8 by b-oxidation
D)28 by TCA plus 7 by b-oxidation

Question 9

Which of the following tissues stores triacylglycerols?

A)liver
B)heart
C)spleen
D)fat

Question 10

Which of the following explains why bile salts are important in the initial digestion of triacylglycerols in the intestine?

A)They are coenzymes for pancreatic lipase activity.
B)They convert the inactive lipase into the active form leading to digestion.
C)They emulsify the triacylglycerol globules to produce greater surface area,which will increase the activity of the lipase.
D)They permit greater permeability of the triacylglycerols through the intestinal membrane.

Question 11

Which of the following cellular locations is the site for where fatty acids are condensed with coenzyme A to form acyl-CoA for b-oxidation?

A)mitochondrial matrix
B)cytoplasm
C)outer mitochondrial membrane
D)inner mitochondrial membrane

Question 12

Across which of the following membranes does carnitine carry long-chain fatty acyl groups?

A)intestinal
B)plasma
C)Golgi
D)inner mitochondrial

Question 13

Which of the following lipid components are produced in the duodenum by the enzyme pancreatic lipase during lipid digestion?

A)diacylglycerols and fatty acids
B)fatty acids and glycerol
C)triacylglycerols and glycerol
D)monoacylglycerols and fatty acids

Question 14

How many times must the ?-oxidation cycle be repeated for the complete oxidation of a saturated fatty acid with 16 carbons?

A)4
B)6
C)7
D)8

Question 15

Which of the following hormones does NOT cause fatty acid mobilization in adipose cells?

A)ACTH (adrenocorticotropic hormone)
B)glucagon
C)insulin
D)epinephrine (adrenaline)

Question 16

Which of the following regarding the activation of a fatty acid to an acyl-CoA is correct?

A)It involves the formation of a high-energy thioester linkage.
B)Activation is accompanied by the hydrolysis of ATP to ADP and Pi.
C)An acyl-adenylate intermediate is formed.
D)Hydrolysis of ATP produces AMP and PPi,with further hydrolysis of PPi to drive the reaction.

Question 17

Which of the following classes of enzymes does enoyl-CoA hydratase belong to?

A)transferase
B)hydrolase
C)lyase
D)ligase

Question 18

Which of the following is NOT involved with the transport of fatty acyl groups from the cytosol to the matrix?

A)carnitine acyltransferase I
B)fatty acyl-CoA in matrix
C)O-acylcarnitine
D)ATP

Question 19

Which of the following is a feature of chylomicrons?

A)They are formed in adipose tissue.
B)They contain more phospholipid than triacylglycerol molecules.
C)They transport dietary triacylglycerols through the bloodstream.
D)They are formed in and secreted by the liver.

Question 20

How many NAD⁺ are reduced in the b-oxidation of stearoyl-CoA to form 9 molecules of acetyl-CoA?

A)8
B)9
C)12
D)16

Question 21

Which of the following regarding for 2,4-dienoyl-CoA reductase is correct?

A)oxidizes trans-?^?,cis-?⁴ double bonds to trans-?³
B)uses NADH
C)cooperates with ?-oxidation in fatty acid oxidation
D)involved in saturated fatty acid catabolism

Question 22

Where are ketone bodies synthesized?

A)cytosol of muscle
B)mitochondria of liver
C)endoplasmic reticulum of heart
D)plasma membrane of brain

Question 23

In ketone body biosynthesis,the HMG-CoA lyase reaction is mechanistically the reverse of the first half of the reaction catalyzed by a particular TCA enzyme.Which of the following TCA enzymes does it resemble?

A)aconitase
B)citrate synthase
C)malate dehydrogenase
D)succinyl-CoA synthase

Question 24

During ?-oxidation of certain unsaturated fatty acids,cis-?³-fatty acyl-CoAs are formed that must be converted to trans-?²-fatty acyl-CoAs.Which of the following enzymes converts them to trans-?²-fatty acyl-CoAs?

A)acyl-CoA dehydrogenase
B)enoyl-CoA dehydrogenase
C)isocitrate dehydrogenase
D)succinate dehydrogenase

Question 25

Which of the following regarding methylmalonyl-CoA mutase is correct?

A)does hemolytic cleavage of C-C bond
B)is vitamin B₁₂-dependent
C)has classic B₁₂-enzyme catalyzed rearrangement
D)produces succinyl-CoA

Question 26

Which of the following TCA cycle intermediates is propionyl-CoA ultimately converted to?

A)citrate
B)isocitrate
C)succinyl-CoA
D)succinate

Question 27

Which of the following series correctly describes the conversion of a fatty acid to CO₂?

A)carnitine shuttle;activation to acyl-CoA;b-oxidation;CAC
B)activation to acyl-CoA;carnitine shuttle;b-oxidation;CAC
C)CAC;activation to acyl-CoA;b-oxidation;carnitine shuttle
D)activation to acyl-CoA;b-oxidation;carnitine shuttle;CAC

Question 28

How do ketone body carbons enter the major metabolic pathways of the cells?

A)by conversion to acetyl-CoA
B)by conversion to citrate
C)by conversion to pyruvate
D)by conversion to glucose-6-phosphate

Question 29

Which of the following are the 3 most common ketone bodies?

A)acetoacetate,hydroxyacetone phosphate,and butyrate
B)acetone,b-hydroxybutyrate,and acetoacetate
C)acetoacetate,acetyl-CoA,and acetone
D)butyrate,acetoacetate,and acetone

Question 30

Which of the following is the potential major source of energy for the brain during prolonged starvation?

A)ketone bodies
B)fatty acids
C)amino acids
D)glucose

Question 31

Which of the following are the b-oxidation products of oleic acid (18:1ᴰ⁹),and how many ATP equivalents are required for activation?

A)8 acetyl CoA,7 NADH,6 FADH₂;2 ATP equivalents
B)8 acetyl CoA,7 NADH,7 FADH₂;1 ATP equivalents
C)9 acetyl CoA,8 NADH,7 FADH₂;1 ATP equivalents
D)9 acetyl CoA,8 NADH,7 FADH₂;2 ATP equivalents

Question 32

How are ketone bodies transported to the tissues for utilization?

A)complexed to serum albumin
B)incorporated into VLDLs
C)complexed to fatty acid-binding protein
D)freely dissolved in serum