Score for this attempt: 80 out of 80
Submitted Mar 5 at 12:08pm
This attempt took 88 minutes.
Question 1
2 / 2 pts
In the β-oxidation pathway, the oxidation occurs at carbon ________ with the
acetyl group that becomes acetyl-CoA derived from the ________ end of the
fatty acid.
1; methyl
2; carbonyl
C !
3; carbonyl
2; methyl
1; carbonyl
Question 2
2 / 2 pts
Which of the following is considered an omega-3 fatty acid?
8,11,14-Eicosatrienoic acid
5,8,11,14-Eicosatetraenoic acid
C !
9,12,15-Octadecatrienoic acid
9,12-Octadecadienoic acid
6,9,12-Octadecatrienoic acid
Question 3
2 / 2 pts
During β-oxidation in the peroxisome, what reoxidizes the enzyme-bound
FADH2 during the first oxidation of the pathway?
H2O2
FMN
C !
O2
NAD+
none of the above
Question 4
2 / 2 pts
Which of the following lipids would not likely be found in a lipid raft?
I. glycosphingolipids
II. glycerophospholipids
III. cholesterol
IV. palmitoleic acid
I, II, IV
C !
II, IV
I, IV
IV
III, IV
Question 5
2 / 2 pts
During β-oxidation of an odd-chain fatty acid, the last three carbon atoms
from the oxidized fatty acid enter the citric acid cycle as ________.
propionyl-CoA
succinate
fumarate
methylmalonyl-CoA
C !
succinyl-CoA
Question 6
2 / 2 pts
Which of the following explains why free fatty acids do not form bilayers?
the width of the nonpolar head is less than the polar tail
the width of the polar head is less than the nonpolar tail
C !
the width of the polar head is greater than the nonpolar tail
the width of the nonpolar head is greater than the polar tail
the width of the polar head is equal to the nonpolar tail
Question 7
2 / 2 pts
A membrane raft is a(n) ________ in the lipid bilayer of a cell membrane.
integral membrane protein oriented to the extracellular side
transmembrane protein
C !
region of high cholesterol and sphingolipid content
integral membrane protein oriented to the intracellular side
none of the above
Question 8
2 / 2 pts
Which of the following statements describes one reason that plant oils are
generally healthier for human consumption than animal fats?
C !
Plant oils usually contain more unsaturated fatty acids than animal fats.
Plant oils usually have more saturation than animal fats.
Plant oils have shorter chain fatty acids than animal fats.
Plant oils are glycerol based rather than phospholipid based.
Plant oils usually contain more trans fatty acids than animal fats.
Question 9
2 / 2 pts
What are the β-oxidation products of stearic acid, a saturated fatty acid with
18 carbons?
8 NADH, 9 QH2, 9 acetyl-CoA
8 NADH, 7 QH2, 9 acetyl-CoA
C !
8 NADH, 8 QH2, 9 acetyl-CoA
9 NADH, 8 QH2, 9 acetyl-CoA
9 NADH, 9 QH2, 9 acetyl-CoA
Question 10
2 / 2 pts
The activation of acetyl-CoA for fatty acid synthesis is achieved by
converting the acetyl-CoA into ________.
β-hydroxybutyryl-CoA
C !
malonyl-CoA
HMG-CoA
propionyl-CoA
acetoacetyl-CoA
Question 11
2 / 2 pts
To oxidize the fatty acids in a triacylglycerol, what must occur first?
C !
lipolysis
fatty acid activation
transport into the mitochondria
oxidation of a carbon-carbon single bond to an alkene
none of the above
Question 12
2 / 2 pts
The major lipid component of cell membranes are ________.
triacylglycerols
cholesterol
C !
glycerophospholipids
gangliosides
cerebrosides
Question 13
2 / 2 pts
Cholesterol is converted into ________, a molecule that aids in the absorption
of dietary lipids.
β-estradiol
C !
cholate
aldosterone
cortisol
progesterone
Question 14
2 / 2 pts
What is used to activate phosphoethanolamine prior to reaction with a
diacylglycerol?
TTP
ATP
UTP
C !
CTP
GTP
Question 15
2 / 2 pts
Which of the following amino acids from an integral membrane protein would
likely contact the membrane?
Gln
Asp
Glu
C !
Ala
Asn
Question 16
2 / 2 pts
What mechanism is used to control whether HMG-CoA is used for ketone
body synthesis or for cholesterol synthesis?
depletion of products influences where HMG-CoA will be shunted
control of NADPH versus acetyl-CoA levels
control of HMG-CoA lyase versus HMG-CoA reductase
control of NADPH:NAD+ levels
C !
ketone bodies are synthesized in the mitochondria; cholesterol is synthesized
in the cytoplasm
Question 17
2 / 2 pts
Which of the following is a characteristic of integral membrane proteins?
all have carbohydrates attached to the extracellular domain
C !
most of their movement is by lateral diffusion
interactions between proteins makes the membrane highly rigid
transverse diffusion occurs often but rather slowly
none of the above
Question 18
2 / 2 pts
In an α-helical protein that spans a cell membrane, ________ would likely be in
the center of the membrane while ________ would likely be associated with
the polar head groups and ________ would likely be associated with the
aqueous environment
Trp; Asn; Ala
Val; Ser; Thr
C !
Leu; Gln; Asp
Tyr; Glu; Gly
Ile; Arg; Gln
Question 19
2 / 2 pts
Which of the following classes of proteins associates with the membrane
bilayer with the lowest energy and would therefore be most difficult to
separate from the membrane?
extrinsic proteins
lipid-linked proteins
hydrophilic proteins
peripheral proteins
C !
transmembrane proteins
Question 20
2 / 2 pts
Which of the following is the primary building block for the synthesis of
molecules like cholesterol or ubiquinone?
sphingosine
acetyl-CoA
choline
palmitic acid
C !
isoprene
Question 21
2 / 2 pts
Which of the following statements describes integral membrane proteins?
I. They protect the contents of the cell from chaotropic agents such as urea.
II. They are easily dissociated from the membrane by changes in pH or high
salt concentration.
III. They are held in place by hydrophobic effects between the membrane and
hydrophobic amino acids.
I
II
I, III
C !
III
I, II, III
Question 22
2 / 2 pts
Which of the following best describes the sequence of events for the
synthesis of phosphatidylcholine?
CDP-choline reacts with a monoacylglycerol followed by fatty acid addition
a diacylglycerol pyrophosphate reacts with choline
phosphocholine condenses with glycerol-3-phosphate, then two fatty acids
are added
C !
CDP-choline reacts with a diacylglycerol
none of the above
Question 23
2 / 2 pts
Which of the following explains how phosphatidylserine is synthesized?
serine reacts with a diacylglycerol pyrophosphate
serine reacts with a CDP-diacylglycerol
C !
serine displaces the ethanolamine from a phosphatidylethanolamine
the ethanolamine group of phosphatidylethanolamine is carboxylated to form
serine
CDP-serine reacts with diacylglycerol
Question 24
2 / 2 pts
What are the characteristics of most unsaturated fatty acids found within a
human cell?
deprotonated carboxylic acid and trans double bonds
protonated carboxylic acid and trans double bonds
C !
deprotonated carboxylic acid and cis double bonds
protonated carboxylic acid and cis double bonds
none of the above
Question 25
2 / 2 pts
What pathway supplies the bulk of the NADPH needed for fatty acid
synthesis in mammals?
C !
pentose phosphate pathway
glycolysis
light reactions of photosynthesis
citric acid cycle
all of the above
Question 26
2 / 2 pts
What enzyme is the major control point of cholesterol synthesis in humans?
isopentenyl pyrophosphate synthase
HMG-CoA lyase
HMG-CoA synthase
C !
HMG-CoA reductase
thiolase
Question 27
2 / 2 pts
Each round of β-oxidation of a saturated fatty acyl-CoA produces ________.
C !
1 NADH, 1 QH2, 1 acetyl-CoA
1 NADH, 1 QH2, 2 acetyl-CoA
1 NADH, 1 QH2, 1 H2O, 1 acetyl-CoA
1 NADH, 1 QH2, 1 CO2, 1 acetyl-CoA
2 NADH, 1 QH2, 1 acetyl-CoA
Question 28
2 / 2 pts
Which of the following best describes the order for the conversion of
glycerol-3-phosphate into a triacylglycerol?
1 acyltransferase reaction, 1 phosphatase reaction, then 2 more
acyltransferase reactions
C !
2 acyltransferase reactions, 1 phosphatase reaction, then 1 acyltransferase
reaction
1 phosphatase reaction then 3 acyltransferase reactions
1 acyltransferase reaction, 1 phosphatase reaction, 1 acyltransferase
reaction, 1 phosphatase reaction, then 1 acyltransferase reaction
3 acyltransferase reactions then 1 phosphatase reaction
Question 29
2 / 2 pts
Which of the following is the starting metabolite in ketone body biosynthesis?
acetyl CoA and propionyl CoA
C !
acetyl CoA
propionyl CoA
acetyl CoA and malonyl CoA
malonyl CoA
Question 30
2 / 2 pts
Which of the following types of fatty acids would be oxidized exclusively in
the peroxisome instead of the mitochondria?
C !
branched-chain fatty acids
short-chain saturated fatty acids
very long-chain saturated fatty acids
monounsaturated fatty acids
polyunsaturated fatty acids
Question 31
2 / 2 pts
Of the major lipoproteins, ________ are highest in cholesterol and cholesterol
esters while ________ are highest in triacylglycerols.
HDL; VLDL
VLDL; LDL
chylomicrons; HDL
LDL; VLDL
C !
LDL; chylomicrons
Question 32
2 / 2 pts
What is the product of fatty acid activation?
C !
acyl-CoA
acyladenylate
acyl-carnitine
pyrophosphate
acyl ester
Question 33
2 / 2 pts
Which of the following aspects of membrane protein movement is explained
by the fluid mosaic model?
C !
proteins that are mobile only in a small area are sequestered by proteins
attached to the cytoskeleton
proteins confined to a lipid raft are linked to phosphatidylserine via and
amide bond
proteins that are immobile are often esterified to cholesterol via an Asp
residue
proteins that freely diffuse through the membrane often undergo flip-flopping
none of the above
Question 34
2 / 2 pts
The activation of acetyl-CoA for fatty acid synthesis is achieved by
converting the acetyl-CoA into ________.
propionyl-CoA
C !
malonyl-CoA
acetoacetyl-CoA
β-hydroxybutyryl-CoA
HMG-CoA
Question 35
2 / 2 pts
Ketone bodies are produced in the ________ and used by the ________ only
under conditions such as a prolonged fast.
C !
liver; brain
kidneys; brain
liver; heart
kidneys; heart
liver; skeletal muscle
Question 36
2 / 2 pts
Which enzyme is the rate-determining step for fatty acid synthesis?
3-ketoacyl-ACP reductase
trans acylase
C !
acetyl-CoA carboxylase
ATP-citrate lyase
3-hydroxyacyl-ACP dehydrase
Question 37
2 / 2 pts
Which of the following statements describes integral membrane proteins?
C !
the amino acids that contact the core of the membrane are hydrophobic
their association with the membrane is through an attached fatty acyl or
prenyl group
they tend to be water soluble
they are easily removed by changes in pH or high salt
they never completely span the lipid bilayer
Question 38
2 / 2 pts
Which of the following is true regarding membrane asymmetry?
transverse diffusion occurs very quickly
a flippase causes lateral diffusion to occur very rapidly
carbohydrates attached to membrane lipids are usually found on the
cytosolic side of the membrane
lateral diffusion occurs very slowly
C !
none of the above
Question 39
2 / 2 pts
Which of the following is the correct sequence of events in cholesterol
synthesis? (Note: not all events in the sequence are included.)
HMG—CoA > isopentyl pyrophosphate > farnesyl pyrophosphate > geranyl
pyrophosphate
HMG—CoA > phosphomevalonate > squalene > farnesyl pyrophosphate
C !
dimethylallyl pyrophosphate > geranyl pyrophosphate > farnesyl
pyrophosphate > squalene
isopentyl pyrophosphate > squalene > oxidosqualene > geranyl
pyrophosphate
mevalonate > dimethylallyl pyrophosphate > farnesyl pyrophosphate >
geranyl pyrophosphate
Question 40
2 / 2 pts
Which of the following is true regarding the enzyme acetyl-CoA carboxylase?
I. It catalyzes the rate-limiting step in fatty acid oxidation.
II. It requires S-adenosylmethionine.
III. It produces malonyl CoA.
IV. It uses acetyl CoA.
I, II, III, IV
I only
III only
I, III, IV
C !
III, IV
Quiz Score: 80 out of 80
