Deck 20: Lipid Metabolism

Question 1

Matching
Choose the correct answer from the list. Not all the answers will be used.
Fatty acid synthesis requires both acetyl-CoA and ________ as initiator molecules.

A)HDL
B)propionyl-CoA
C)LDL
D)Dihydroxyacetone phosphate
E)malonyl-CoA
F)ACP
G)chylomicrons
H)phosphopantetheine
I)flavin
J)albumin
K)ketone bodies
L)cholesterol

Answer 1

malonyl-CoA

Question 2

Matching
Choose the correct answer from the list. Not all the answers will be used.
Cholesterol and other lipids are transported from tissues to the liver by ________.

A)HDL
B)propionyl-CoA
C)LDL
D)Dihydroxyacetone phosphate
E)malonyl-CoA
F)ACP
G)chylomicrons
H)phosphopantetheine
I)flavin
J)albumin
K)ketone bodies
L)cholesterol

Answer 2

HDL

Question 3

Digestion of triacylglycerols is aided by the cholesterol derivatives synthesized by the liver known as

A)bile acids.
B)lipoproteins.
C)lanosterols.
D)chylomicrons.
E)colipases.

Answer 3

bile acids.

Question 4

Matching
Choose the correct answer from the list. Not all the answers will be used.
Cells take up ____ by receptor mediated endocytosis.

A)HDL
B)propionyl-CoA
C)LDL
D)Dihydroxyacetone phosphate
E)malonyl-CoA
F)ACP
G)chylomicrons
H)phosphopantetheine
I)flavin
J)albumin
K)ketone bodies
L)cholesterol

Question 5

Triacylglycerols are synthesized by ____ during times of starvation via a process known as ____.

A)Dihydroxyacetone phosphate; ketosis
B)Dihydroxyacetone phosphate; glyceroneogenesis
C)acetyl CoA; ketosis
D)acetyl CoA; glyceroneogenesis
E)ketone bodies; ketosis

Question 6

Matching
Choose the correct answer from the list. Not all the answers will be used.
The glycerol backbone of triacylglycerols is catabolized to ________ .

A)HDL
B)propionyl-CoA
C)LDL
D)Dihydroxyacetone phosphate
E)malonyl-CoA
F)ACP
G)chylomicrons
H)phosphopantetheine
I)flavin
J)albumin
K)ketone bodies
L)cholesterol

Question 7

Which of the following statements about apolipoproteins (with the possible exception of apoB-100)is TRUE?
I.The apolipoproteins are water-soluble and loosely associate with the lipoproteins.
II.The apolipoproteins contain helices with hydrophobic and hydrophilic groups on opposite sides of the helical cylinder.
III.The apolipoproteins are synthesized in the intestinal tissues.
IV.The apolipoproteins appear to float on the surface of phospholipids.

A)I only
B)I and II
C)III, IV
D)I, II, III
E)I, II, IV

Question 8

Which of the following is required for entry of fatty acids into the oxidation pathway?
I.priming via the enzyme acyl CoA synthetase
II.conservation of free energy from ATP hydrolysis by use of a thioester linkage
III.transport to the cytosol for oxidation via a carnitine carrier protein
IV.hydrolysis of carnitine palmitoyl transfer protein

A)I, II
B)I, II, III
C)I, II, III, IV
D)III, IV
E)I, III

Question 9

Which of the following vitamins is part of the prosthetic group 5'-deoxyadenosylcobalamin?

A)B₁
B)B₂
C)B₆
D)B₁₂
E)none of the above

Question 10

Matching
Choose the correct answer from the list. Not all the answers will be used.

-The molecules acetoacetate, acetone, and d- $\beta$ -hydroxybutyrate are metabolic fuels termed ________.

A)HDL
B)propionyl-CoA
C)LDL
D)Dihydroxyacetone phosphate
E)malonyl-CoA
F)ACP
G)chylomicrons
H)phosphopantetheine
I)flavin
J)albumin
K)ketone bodies
L)cholesterol

Question 11

Which of the following accurately ranks lipoproteins from highest to lowest density?

A)chylomicrons > HDL > LDL > IDL > VLDL
B)HDL > IDL > LDL > VLDL > chylomicrons
C)HDL > LDL > IDL > VLDL > chylomicrons
D)chylomicrons > VLDL > IDL > LDL > HDL
E)VLDL > IDL > LDL > HDL > chylomicrons

Question 12

Matching
Choose the correct answer from the list. Not all the answers will be used.
Lipoproteins formed in the intestinal mucosal cells are called ________.

A)HDL
B)propionyl-CoA
C)LDL
D)Dihydroxyacetone phosphate
E)malonyl-CoA
F)ACP
G)chylomicrons
H)phosphopantetheine
I)flavin
J)albumin
K)ketone bodies
L)cholesterol

Question 13

Matching
Choose the correct answer from the list. Not all the answers will be used.
Acyl carrier protein (ACP)contains a ________ prosthetic group.

A)HDL
B)propionyl-CoA
C)LDL
D)Dihydroxyacetone phosphate
E)malonyl-CoA
F)ACP
G)chylomicrons
H)phosphopantetheine
I)flavin
J)albumin
K)ketone bodies
L)cholesterol

Question 14

Which of the following would result in a net increase in uptake of LDL by the liver?

A)increased availability of LDL receptors
B)high levels of cholesterol synthesis
C)increased availability of clathrin triskelions
D)all of the above
E)none of the above

Question 15

Matching
Choose the correct answer from the list. Not all the answers will be used.
________ is formed from ordered sequence of condensation of isoprene units.

A)HDL
B)propionyl-CoA
C)LDL
D)Dihydroxyacetone phosphate
E)malonyl-CoA
F)ACP
G)chylomicrons
H)phosphopantetheine
I)flavin
J)albumin
K)ketone bodies
L)cholesterol

Question 16

______, a condition in which acetoacetate production exceeds it metabolism and results in a sweet breath odor due to nonenyzmatic ___ of acetoacetate to _____.

A)ketosis; decarboxylation; hydroxylbutryate
B)ketosis; carboxylation; hydroxylbutryate
C)ketosis; carboxylation; acetone
D)glyceroneogenesis; decarboxylation; hydroxylbutryate
E)glyceroneogenesis; decarboxylation; acetone

Question 17

The activity of lipases is controlled in part by a process known as ____ which functions effectively due to the ____ where lipases are active.

A)interfacial activation; lipid-water interface
B)lipase activation; lipid-water interface
C)lipase activation; bile salt-water interface
D)micelle activation; water-salt interface
E)none of the above

Question 18

Matching
Choose the correct answer from the list. Not all the answers will be used.
Free fatty acids bind to ________ for circulation in the bloodstream.

A)HDL
B)propionyl-CoA
C)LDL
D)Dihydroxyacetone phosphate
E)malonyl-CoA
F)ACP
G)chylomicrons
H)phosphopantetheine
I)flavin
J)albumin
K)ketone bodies
L)cholesterol

Question 19

Matching
Choose the correct answer from the list. Not all the answers will be used.

-The $\beta$ oxidation of odd-numbered fatty acids results in ________ as a final product.

A)HDL
B)propionyl-CoA
C)LDL
D)Dihydroxyacetone phosphate
E)malonyl-CoA
F)ACP
G)chylomicrons
H)phosphopantetheine
I)flavin
J)albumin
K)ketone bodies
L)cholesterol

Question 20

Two phosphatidylglycerol molecules condense to form the molecule ______, and glycerol is eliminated as the side product.

A)phosphatidic acid
B)cardiolipin
C)plasmalogen
D)sphingomyelin
E)squalene

Question 21

Which statement concerning fatty acid synthesis is TRUE?
I.The process occurs in the cytosol.
II.In eukaryotes, the process occurs on a single large protein.
III.The growing acyl chain is carried on an acyl carrier protein instead of coenzyme A.
IV.The process requires two NADPH per acetyl group (2 carbons)added.

A)I, II
B)II, III
C)I, II, III, IV
D)III, IV
E)I, III, IV

Question 22

Which of the following best describes arachidonic acid?

A)a 20-carbon isoprene-based intermediate of cholesterol synthesis
B)a 20-carbon fatty acid essential for cholesterol synthesis
C)a 20-carbon isoprene-based compound used for synthesis of prostaglandins
D)a 20-carbon fatty acid used for synthesis of prostaglandins
E)a 2-carbon compound that functions in conjunction with a fatty acid carrier protein for transport of primed fatty acids

Question 23

Which statement concerning phospholipid synthesis is true?

A)Addition of polar "head groups" to diacylglycerol usually involves CDP derivatives.
B)Addition of polar "head groups" to diacylglycerol usually involves UDP adducts.
C)Addition of fatty acyl "tails" to glycerol usually involves CDP adducts.
D)Addition of fatty acyl "tails" to glycerol usually involves UDP adducts.
E)None of the above is true.

Question 24

Which of the following statements about peroxisomes is FALSE?

A)( $\beta$ oxidation in peroxisomes can shorten very long fatty acids.)
B)Mammalian peroxisomes can synthesize some lipids, including bile salts.
C)In plants, peroxisomes and glyoxysomes serve as the site of $\beta$ oxidation.
D)Long chain fatty acids are transported into the peroxisome via a carnitine carrier protein where they are activated for oxidation.
E)( $\beta$ oxidation in peroxisomes varies slightly from the mitochondrial process.)

Question 25

In which location listed below does the following reaction take place?
HMG-CoA → acetoacetate + Acetyl-CoA

A)cytosol of cardiomyocytes
B)mitochondria of cardiomyocytes
C)cytosol of liver cells
D)mitochondria of liver cells
E)all of the above

Question 26

Which of the following diets would most likely promote the formation of ketone bodies?

A)high simple carbohydrates, low fat
B)high complex carbohydrates, high fructose
C)high fat, high protein, low carbohydrate
D)low fat, high protein, high complex carbohydrates
E)high fructose; high whole grain carbohydrates

Question 27

Which of the following is TRUE regarding the enzyme acetyl-CoA carboxylase?
I.It catalyzes the first committed step in fatty acid oxidation.
II.It requires S-adenosylmethionine.
III.It produces malonyl CoA
IV.It uses acetyl CoA

A)I, II, III, IV
B)I only
C)I, III, IV
D)III, IV
E)III only

Question 28

Pain and inflammation are triggered by ___ which are synthesized by an enzyme inhibited by ____.

A)cardiolipins; aspirin
B)prostaglandins; aspirin
C)analgesics; statins
D)prostaglandins; COX-1
E)cyclooxygen; NSAIDS

Question 29

An enzyme that is inhibited by the statin group of drugs (e.g.Lipitor)is

A)phospholipase a2.
B)hormone sensitive lipase.
C)HMG CoA reductase.
D)desaturase.
E)glycerol kinase.

Question 30

The mechanism of the condensing enzyme (KS)of fatty acid synthase is best described as

A)base catalysis using a glu residue in the active site
B)acid catalysis using a glu residue in the active site
C)base catalysis using a cys residue in the active site
D)acid catalysis using a cys residue in the active site
E)covalent catalysis using a cys residue in the active site

Question 31

What is the net production of ATP from complete catabolism of the following fatty acid to CO₂ and H₂O?

A)< 50
B)51 - 90 [70]
C)91 - 120
D)121 - 150
E)151 +

Question 32

Which of the following is the source of the two carbon fragments in fatty acids biosynthesis?

A)acetyl CoA
B)malonyl CoA
C)palmitic acid
D)propionyl CoA
E)ceramides

Question 33

Which enzyme catalyses the key regulatory step of cholesterol synthesis?

A)( $\beta$ -ketothiolase)
B)HMG-CoA synthase
C)HMG-CoA reductase
D)mevalonate-5-phosphotransferase
E)phenyltransferase

Question 34

Knoop's experiments with fatty acids

A)involved the novel use of chemical labels to elucidate metabolic mechanisms.
B)demonstrated that fatty acids are broken down by two carbons at a time by oxidation at the ω carbon.
C)demonstrated a distinct difference in the mechanism of odd chain versus.even chain fatty acid oxidation.
D)A and B
E)A, B, and C

Question 35

Which of the following compounds are required to make sphingosine?
I.palmitoyl-CoA
II.serine
III.acetyl-CoA
IV.isoprene
V.arachidonic acid

A)I, II
B)I, III
C)II, IV
D)IV, V
E)II, V

Question 36

Sphinganine is an intermediate in the synthesis of which of the following?
I.ceramides
II.spingomyelins
III.cerebrosides
IV.prostaglandins

A)I only
B)I, II
C)I, II, III
D)II, III
E)I, II, IV

Question 37

In which cellular compartment does the following reaction take place?
HMG-CoA + 2 NADPH → mevalonate + 2 NADP⁺ + Acetyl-CoA

A)cytosol of liver cells
B)mitochondria of liver cells
C)cells in the intestinal lumen
D)lysosomal fluid
E)all of the above

Question 38

An important structural lipid found in nerve cell membranes, ______, is a type of ______.

A)sphingomyelin, phospholipid
B)phosphatidylcholine, phospholipid
C)palmitate, glycerophospholipid
D)glucagon, hormone
E)none of the above

Question 39

Cholesterol is a precursor to
I.prostaglandins
II.vitamin K
III.steroid hormones such as androgens
IV.bile acids

A)I, III, IV
B)I, II, III, IV
C)III only
D)IV only
E)III, IV

Question 40

Which of the following could be produced by the reaction of two or more of phosphatidic acids with two or more glycerol-3-phosphates?
I.phosphatidylglycerol
II.cardiolipin
III.phosphatidylinositol
IV.gangliosides

A)I, II, III, IV
B)II, III
C)I, III
D)I, II
E)III only

Question 41

Which of the following is the correct sequence of events in cholesterol synthesis? (Note: not all events in the sequence are included)

A)HMG-CoA > isopentyl pyrophosphate > farnesyl pyrophosphate > geranyl pyrophosphate
B)isopentyl pyrophosphate > squalene > oxidosqualene > geranyl pyrophosphate
C)dimethylallyl pyrophosphate > geranyl pyrophosphate > farnesyl pyrophosphate > squalene
D)HMG -CoA > phosphomevalonate > squalene > farnesyl pyrophosphate
E)mevalonate > dimethylallyl pyrophosphate > farnesyl pyrophosphate > gernayl pyrophosphate

Question 42

PGH₂ is synthesized from ______ and triggers pain and ________.

A)cardiolipins; foam cell development
B)steroids; fever
C)salicylic acid; foam cell development
D)NSAIDS; COX-1
E)arachidonate; inflammation

Question 43

Which of the following is FALSE regarding HMG-CoA reductase?

A)HMG-CoA reductase is highly regulated.
B)The active site is tightly bound by statins.
C)HMG-CoA reductase levels are increased as a result of high cholesterol concentrations in the ER
D)HMG-CoA reductase levels are decreased as a result of high cholesterol concentrations in the ER.
E)HMG-CoA reductase is levels are decreased by the same factor that down regulated production of the LDL receptors

Question 44

Which of the following is NOT an example of a problem sometimes associated with unsaturated fatty acid breakdown?

A)β, $\gamma$ double bond
B)α, β double bond
C)unanticipated isomerization
D)inhibition of hydratase by a double bond
E)All of the above are problems.

Question 45

Which of the following compounds is produced by the multistep cyclization of squalene?

A)lanosterol
B)geranyl pyrophosphate
C)fanesyl pyrophosphate
D)isoprene
E)isopentyl pyrophosphate

Question 46

Which of the following enzymes is NOT involved in the tricarboxylate transport system?

A)citrate synthase
B)ATP citrate lyase
C)malate dehydrogenase
D)malic enzyme
E)All are involved in the transport of acetyl-CoA into the cytosol

Question 47

Which of the following is the starting metabolite in ketone body biosynthesis?

A)acetyl CoA
B)malonyl CoA
C)propionlyl CoA
D)acetyl CoA and propionyl CoA
E)acetyl CoA and malonyl CoA

Question 48

LDL taken up by the liver is

A)broken down into fatty acids and amino acids.
B)taken up by the ER and used to control synthesis of HMG CoA reductase and LDL receptor synthesis.
C)converted into clathrin and recycled.
D)irreversibly bound to LDL receptors.
E)excreted in a clathrin coated vesicle.

Question 49

Which of the following components would be condensed to form acetoacetate?

A)acetyl CoA and acetyl-CoA
B)HMG-CoA and acyl-CoA
C)acetone and betahydroxybutyrate
D)malonyl-CoA and acyl-CoA
E)DHAP and glycerol-3-phosphate

Question 50

Which of the following drugs acts by acetylating a serine residue preventing adequate enzyme activity?

A)ibuprofen
B)acetaminophen
C)Vioxx
D)aspirin
E)Celebrex

Question 51

Considering the figure below, what compound would be formed by action of acyl-CoA dehydrogenase?

A)
B)
C)
D)
E)