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MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the question.
1) Why are triacylglycerols able to provide more energy than carbohydrates (gram for gram)?
A) The triacylglycerols are less soluble in water than the carbohydrates.
B) The carbohydrates contain fewer carbon-carbon bonds.
C) The carbohydrates are already in a more oxidized state than the triacylglycerols.
D) The triacylglycerols have an extremely high group transfer potential.
1)
2) There are four steps in the β-oxidation pathway. Some reaction types are listed below. Give the
proper reaction types in the order that they occur in the β-oxidation pathway.
2)
1.
2.
3.
4.
5.
6.
7.
condensation
oxidation
reduction
thiolysis
hydration
phosphorylation
rearrangement
A) 2, 5, 2, 4
B) 1, 2, 3, 5
C) 1, 7, 2, 2
D) 6, 3, 4, 2
3) If the carbonyl carbon of a fatty acyl CoA molecule with a C10 chain is labeled with 14C, how many
rounds of β-oxidation are required to produce a radioactively labeled acetyl CoA?
A) one
B) two
C) four
D) five
3)
4) How many cycles of β-oxidation are required to completely process a saturated C18 fatty acid?
A) 6
B) 8
C) 9
D) 18
4)
5) Which enzyme is needed for the oxidation of odd-chain saturated fatty acids that is not needed for
even-chain fatty acids?
B) methylmalonyl-CoA racemase
A) propionyl-CoA carboxylase
C) methylmalonyl-CoA mutase
D) All of the above
5)
6) To oxidize the fatty acid molecule shown below, what enzyme(s) are needed in addition to the
enzymes needed for β-oxidation?
6)
A) 2,4-dienoyl-CoA reductase only
B) enoyl-CoA isomerase only
C) both enoyl-CoA isomerase and 2,4-dienoyl-CoA reductase
D) No additional enzymes are needed besides the normal ones for β-oxidation.
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7) To oxidize the fatty acid molecule shown below, what enzyme(s) is(are) needed in addition to the
enzymes needed for β-oxidation?
7)
A) 2,4-dienoyl-CoA reductase only
B) enoyl-CoA isomerase only
C) both enoyl-CoA isomerase and 2,4-dienoyl-CoA reductase
D) No additional enzymes are needed besides the normal ones for β-oxidation.
8) The conversion of the fatty acid palmitate (C 16) to carbon dioxide via β-oxidation, the citric acid
cycle and oxidative phosphorylation yield approximately ________ ATP equivalents.
A) 3
B) 32
C) 106
D) 800
8)
9) What is the main function of the carnitine shuttle system?
A) To aid in the assembly of chylomicrons.
B) To carry cholesterol from its site of synthesis in the endoplasmic reticulum to the plasma
membrane.
C) To transport newly synthesized sphingolipids to the blood.
D) To transport fatty acids into the mitochondrion.
9)
10) The elongation of fatty acids is a repetition of three reactions adding carbons from ________ after
each cycle until completion.
B) malonyl CoA
C) malonyl ACP
D) acetyl ACP
A) acetyl CoA
10)
11) Which of the following is the regulated step of fatty acid synthesis in eukaryotes?
A) transportation of mitochondrial acetyl CoA into the cytosol
B) assembly of the fatty acid chain
C) carboxylation of acetyl CoA
D) All of the above
11)
12) The first step in fatty acid synthesis is the formation of ________ from acetyl CoA and carbon
dioxide.
B) acetoacetyl CoA
A) acetyl ACP
D) acetoacetyl ACP
C) malonyl CoA
12)
13) Linoleate is an essential fatty acid in mammalian diets because mammalian cells ________.
A) do not have a desaturase that acts beyond the carbon-9 position
B) can use it to synthesize eicosanoids
C) do not use this acid for biosynthesis
D) synthesize it from arachidonate
13)
14) Which of the following is a true statement, concerning HMG-CoA reductase?
A) The product of the reaction it catalyzes is acetoacetyl CoA.
B) It is regulated by covalent modification of a serine in its active site.
C) It causes the production of NADPH.
D) It catalyzes the first committed step in cholesterol biosynthesis.
14)
15) Cholesterol is a precursor for each of the following, except
A) testosterone.
B) bile salts.
C) vitamin D.
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15)
D) vitamin C.
16) Drugs called statins lower cholesterol levels because they ________.
B) bind bile salts
A) inhibit HMG-CoA reductase
C) degrade HMG-CoA reductase
D) bind serum cholesterol
16)
17) Elevated levels of the hormone ________ stimulate the conversion of triacylglycerols stored in
adipose cells to free fatty acids and monoacylglycerols to provide energy when carbohydrate stores
are depleted.
A) epinephrine
B) glucagon
C) insulin
D) ergosterol
17)
18) During the fed state, which of the following occur(s)?
A) allosteric inhibition of carnitine acyltransferase I
B) insulin stimulation of malonyl CoA formation
C) insulin inhibition of the hydrolysis of stored triacylglycerols
D) All of the above
18)
19) Why is it undesirable to have high concentrations of free fatty acids in cells?
A) They are unstable, free radicals that can react to form toxic substances.
B) They are amphipathic and act as detergents that can degrade membranes.
C) They inhibit the uptake of pyruvate by mitochondria.
D) They polymerize easily and can cause the cytosol to become too gel-like.
19)
20) Which dietary lipid usually contains no ester bonds?
A) glycerophospholipids
B) triacylglycerides
C) cholesterol
D) None of the above, all dietary lipids are esterified
20)
21) The largest lipoproteins are the ________.
A) VLDLs
B) LDLs
21)
C) chylomicrons
D) HDLs
22) A patient is found to have a high concentration of cholesterol in the blood and deposits of
cholesterol under the skin. The patient is diagnosed with familial hypercholesterolemia. What is the
likely cause of this condition?
A) Insufficient chylomicron concentration in the blood.
B) Lack of LDL receptors on the surfaces of nonhepatic cells.
C) Overproduction of lysosomal lipases.
D) A deficiency in insulin production by the pancreas.
22)
23) Which is not a ketone body?
A) acetone
C) β-hydroxybutyrate
23)
B) dihydroxyacetone
D) acetoacetate
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Answer Key
Testname: UNTITLED1
1) C
2) A
3) A
4) B
5) D
6) B
7) C
8) C
9) D
10) C
11) C
12) C
13) A
14) D
15) D
16) A
17) A
18) D
19) B
20) C
21) C
22) B
23) B
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