BIOENERGETICS - CHOLESTEROL Flashcards
G protein that promotes activation and
intracellular signaling
A. Ion channel
B. cAMP second messenger
C. Phospholipase C second messenger
D. AOTA
D. AOTA
Least describes eicosanoids
A. Derived from C18 eicosanoids
B. Ibuprofen inhibits cyclooxygenase
C. Prostacyclin inhibits platelet aggregation
D. Group 3 eicosanoids include PGD3, TXA3 and
LTB5
A. Derived from C18 eicosanoids
Arachidonate and some other C20
polyunsaturated fatty acids give rise to
eicosanoids, physiologically and
pharmacologically active compounds known as
prostaglandins (PG), thromboxanes (TX),
leukotrienes (LT), and lipoxins (LX) (see Chapter
21). Physiologically, they are considered to act as
local hormones functioning through G-protein-
linked receptors to elicit their biochemical
effects.
Transfer of fatty acids from cytoplasm to the
mitochondrial matrix requires:
A. ATP, carnitine, co-enzyme A
B. ATP, co-enzyme A, hexokinase
C. ATP, carnitine, pyruvate dehydrogenase
D. ATP, co-enzyme A, pyruvate dehydrogenase
A. ATP, carnitine, co-enzyme A
In the presence of ATP and coenzyme A, the
enzyme acyl-CoA synthetase (thiokinase)
catalyzes the conversion of a fatty acid (or FFA)
to an “active fatty acid” or acyl-CoA, using one
high-energy phosphate and forming
AMP and PPi (Figure 22–1).
Long-chainacyl-CoA (or FFA) cannot penetrate
the inner membrane of mitochondria. In the
presence of carnitine, however, carnitine
palmitoyl transferase-I, located in the outer
mitochondrial membrane, transfers long-chain
acyl group from CoA to carnitine, forming
acylcarnitine and releasing CoA. Acylcarnitine is
able to penetrate the inner membrane and gain
access to the β-oxidation system of enzymes via
the inner membrane exchange transporter
carnitine-acylcarnitine translocase.
Correct order of fxn of enzymes in beta
oxidation
1. Thiolase
2. Enoyl CoA hydratase
3. Beta hydroxyacyl CoA dehydrogenase
4. Acyl CoA dehydrogenase
A. 1,2,3,4
B. 4,3,1,2
C. 4,2,3,1
D. 2,4,3,1
C. 4,2,3,1
Not true of oxidation of 1 mol palmitate in
B oxidation, beginning with free fatty Acid in
cytoplasm.
A. 8 mol of acety CoA formed
B. 2 ATPs required for activating fatty acids
C. Inorganic pyrophosphate (PPi) is produced
D. Carnitine functions as an electron acceptor
B. 2 ATPs required for activating fatty acids
In the presence of ATP and coenzyme A, the
enzyme acyl-CoA synthetase (thiokinase)
catalyzes the conversion of a fatty acid (or FFA)
to an “active fatty acid” or acyl-CoA, using one
high-energy phosphate and forming AMP and
PPi.
Fatty acids with odd number of carbon
enters the citric acid cycle as acetyl coA and
A. Alpha keto glutarate
B. Succinyl coA
C. Acetyl CoA
D. Citrate
B. Succinyl coA
Fatty acids with an odd number of carbon atoms
are oxidized by the pathway of β-oxidation
described above producing acetyl CoA until a
three-carbon (propionyl-CoA) residue remains.
This compound is converted to succinyl-CoA, a
constituent of the citric acid cycle (see Figure 16–
2). Hence, the propionyl residue from an odd-
chain fatty acid is the only part of a fatty acid
that is glucogenic.
Every cycle of beta oxidation of FA yield
A. 1 FAD, 1 NADH, 2 CO2 molecules
B. 1 FADH2, 1 NADH, 1 Acetyl coA
C. 1 FADH2, 1 NAD+, 1 Acetly coA
D. 1 FAD, 1 NAD+, 2 CO2 molecules
B. 1 FADH2, 1 NADH, 1 Acetyl coA
Jamaican vomiting sickness, hypoglycin,
what mechanism?
Jamaican vomiting sickness is caused by
eating the unripe fruit of the akee tree, which
contains the toxin hypoglycin. This inactivates
medium- and short-chain acyl-CoA
dehydrogenase, inhibiting β-oxidation and
causing hypoglycemia.
In extrahepatic tissues, the activation of
acetoacetate to acetyl-coa
A. Acyl CoA synthase
B. HMG CoA lyase
C. CoA transferase
D. Acyl CoA dehydrogenase
C. CoA transferase
In extrahepatic tissues, acetoacetate is activated
to acetoacetyl-CoA by succinyl-CoA-
acetoacetate CoA transferase. CoA is
transferred from succinyl-CoA to form
acetoacetyl-CoA.
Function of lipoprotein lipase
A. Intracellular lipid breakdown of lipoprotein
B. Intestinal uptake of dietary fat
C. Hydrolysis of TAG to supply the fatty needs of
the different tissues of the body
D. Lipoprotein breakdown
C. Hydrolysis of TAG to supply the fatty needs of
the different tissues of the body
Both phospholipids and apo C-II are required as
cofactors for lipoprotein lipase activity, while
apo A-II and apo C-III act as inhibitors. Hydrolysis
takes place while the lipoproteins are attached
to the enzyme on the endothelium.
Triacylglycerol is hydrolyzed progressively
through a diacylglycerol to a monoacylglycerol
and finally to FFA plus glycerol.
Major sphingolipids that lacks in lungs
causing respiratory distress syndrome.
A. Glycospingolipid
B. Inositol Phospholipid
C. Ceramide
D. Dipalmitoyl phosphatidylcholine
D. Dipalmitoyl phosphatidylcholine
Deficiency of Lung Surfactant Causes
Respiratory Distress Syndrome
Lung surfactant is composed mainly of lipid with
some proteins and carbohydrate and prevents
the alveoli from collapsing.
The phospholipid dipalmitoyl
phosphatidylcholine decreases surface tension
at the air-liquid interface and thus greatly
reduces the work of breathing, but other
surfactant lipid and protein components are also
important in surfactant function. Deficiency of
lung surfactant in the lungs of many preterm newborns gives rise to infant
respiratory distress syndrome (IRDS).
Administration of either natural or artificial
surfactant is of therapeutic benefit.
Which of these are a correct match?
A. Krabbes- ceramide
B. Niemann-pick- B-glucosidase
C. Fabry Disease- A- galactosidase
D. Tay-sachs- sphingomyelinase
C. Fabry Disease- A- galactosidase
Least correct of ceramide
Ceramide (see Chapter 21) is synthesized in the
endoplasmic reticulum from the amino acid
serine as shown in Figure 24–7.
Ceramide is an important signaling molecule
(second messenger) regulating pathways
including programmed cell death (apoptosis),
the cell cycle, and cell differentiation and
senescence.
VLDL main lipid component
A. TAG
B. Cholesterol
C. Cholesterol ester
D. Phospholipid
A. TAG
Apoprotein exclusively found in
chylomicron
A. B48
B. B100
C. AOTA
D. NOTA
A. B48
Accumulation of acetyl-coA in the
mitochondria of the liver
A. Broken down into FFA
B. Used as an energy source
C. Converted into oxaloacetate
C. Converted into oxaloacetate
Glycolysis (see Chapter 17), the pentose
phosphate pathway (see Chapter 20), and fatty
acid synthesis (see Chapter 23) all occur in the
cytosol. In gluconeogenesis (see Chapter 19),
substrates such as lactate and pyruvate, which
are formed in the cytosol, enter the
mitochondrion to yield oxaloacetate as a
precursor for the synthesis of glucose in the
cytosol.
Which of the following hormone is not used
in the hydrolysis of lipids?
A. ACTH
B. TSH
C. Glucagon
D. Insulin
D. Insulin
The rate of release of FFA from adipose tissue is
affected by many hormones that influence either
the rate of esterification or the rate of lipolysis.
Insulin inhibits the release of FFA from adipose
tissue, which is followed by a fall in circulating
plasma free fatty acids. Insulin also enhances
lipogenesis and the synthesis of acylglycerol and
increases the oxidation of glucose to CO2 via the
pentose phosphate pathway.
Action of hormone sensitive triacylglycerol
lipase
A. Synthesis of FFA in adipose tissue
B. Hydrolysis of FFA in adipose tissue
C. Synthesis of FFA in liver
D. Hydrolysis of FFA in liver
B. Hydrolysis of FFA in adipose tissue
Triacylglycerol undergoes hydrolysis by a
hormone-sensitive lipase to form FFA and
glycerol. This lipase is distinct from lipoprotein
lipase, which catalyzes lipoprotein triacylglycerol
hydrolysis before its uptake into extrahepatic
tissues.
How are primary bile acids converted to
secondary bile acids?
A. Enzyme produced by exocrine pancreas
B. Enzymes present in duodenum
C. Enzymes present in gallbladder
D. Bacterial oxidation in small intestines
D. Bacterial oxidation in small intestines
Primary bile acids are further metabolized in the
intestine by the activity of the intestinal bacteria.
Thus, deconjugation and 7α-dehydroxylation
occur, producing the secondary bile acids,
deoxycholic acid, and lithocholic acid.
Intracellular cholesterol upregulated by this
transcription factor
A. HMG coA
B. SREBP
C. Sterol proteolytic enzymes
D. HMG coA reductase
B. SREBP
Cholesterol and metabolites repress
transcription of the HMG-CoA reductase via
activation of a sterol regulatory element-
binding protein (SREBP) transcription factor.
SREBPs are a family of proteins that regulate
the transcription of a range of genes involved in
the cellular uptake and metabolism of
cholesterol and other lipids
Dyslipoproteinemia with increased HDL
concetration
A. Familial hypertriacylglycerolemia
B. Familiar hyperalphalipoproteinemia
C. Tangier disease
D. Abetalipoproteinemia
B. Familiar hyperalphalipoproteinemia
Synthesis of glucose from lactate, glycerol
A. Glycolysis
B. Lipolysis
C. Gluconeogenesis
D. Glycogenesis
C. Gluconeogenesis
Gluconeogenesis is the process of synthesizing
glucose or glycogen from noncarbohydrate
precursors. The major substrates are the
glucogenic amino acids (see Chapter 29), lactate,
glycerol, and propionate.
Formed from glucose, used for lactating
mammary gland.
A. Fructose
B. Glucose
C. Galactose
D. Maltose
C. Galactose
Galactose is derived from intestinal hydrolysis of
the disaccharide lactose, the sugar found in milk.
It is readily converted in the liver to glucose.
Oxidation, amination of amino acid alanine
in the liver produces
A. A molecule of pyruvic acid and a molecule of
ammonia
B. A molecule of pyruvic acid and carbon dioxide
C. A molecule of pyruvic acid and water
D. A molecule of pyruvic acid and lactate
A. A molecule of pyruvic acid and a molecule of
ammonia
Most of this is transaminated to alanine, at the
expense of amino acids arising from breakdown
of muscle protein. The alanine, and much of the
keto acids resulting from this transamination are
exported from muscle, and taken up by the liver,
where the alanine is transaminated to yield
pyruvate. The resultant amino acids are largely
exported back to muscle, to provide amino
groups for formation of more alanine, while the
pyruvate provides a substrate for
gluconeogenesis in the liver
Pyruvate Dehydrogenase:
A. Located in the Sarcoplasm
B. Catalyzes the conversion of Pyruvate to
Acetyl-CoA
C. Catalyzes the conversion of Pyruvate to
Lactate
D. Catalyzes the conversion of Lactate to
Pyruvate
E. Uses molecular Oxygen to remove a molecule
of Carbon Dioxide from Pyruvate
B. Catalyzes the conversion of Pyruvate to
Acetyl-CoA
Pyruvate, formed in the cytosol, is transported
into the mitochondrion by a proton symporter.
Inside the mitochondrion, it is oxidatively
decarboxylated to acetyl-CoA by a multienzyme
complex that is associated with the inner
mitochondrial membrane. This pyruvate
dehydrogenase complex is analogous to the α-
ketoglutarate dehydrogenase complex of the
citric acid cycle
Rate of tubular reabsorption of glucose
A. 10mmol/L
B. 2mmol/L
C. 10mmol/min
D. 2mmol/min
E. 2mmol/sec
D. 2mmol/min
The ff substances cause the release of
insulin in the pancreas except:
a. amino acid
b. non-esterified fatty acids
c. ketone bodies
d. secretin
e. none of the above
e. none of the above
Other substances causing release of insulin from
the pancreas include amino acids, nonesterified
fatty acids, ketone bodies, glucagon, secretin,
and the sulfonylurea drugs tolbutamide and
glyburide.
Catalyzes the transfer of 3-C
dihydroxyacetone from the ketose
sedoheptulose-7-phosphate.
A. Transketolase
B. Transaldolase
C. Reductase
D. Transaminase
B. Transaldolase
Transaldolase catalyzes the transfer of a three
carbondihydroxyacetone moiety (carbons 1–3)
from the ketose sedoheptulose-7-phosphate
onto the aldose glyceraldehyde- 3-phosphate to
form the ketose fructose 6-phosphate and the
four-carbon aldose erythrose 4-phosphate.
Enzyme that catalyzes H2O2 in conjunction
with glutathione
A. Glutathione reductase
B. Glutathione dehydrogenase
C. Glutathione peroxidase
D. UDPGIc reductase
E. UDPGIc peroxidase
C. Glutathione peroxidase
Reduced glutathione removes H2O2 in a reaction
catalyzed by glutathione peroxidase, an enzyme
that contains the selenium analog of cysteine
(selenocysteine) at the active site
Hereditary disorder caused by the lack of
xylulose reductase.
A. A. G6PD deficiency
B. Fructosuria
C. Essential Pentosuria
D. Fructosuria
C. Essential Pentosuria
In the rare benign hereditary condition essential
pentosuria, considerable quantities of xylulose
appear in the urine, because of a lack of xylulose
reductase, the enzyme necessary to reduce
xylulose to xylitol
Glucose in lactating mammary gland that is
needed for the synthesis of other tissues for
glycolipid, proteoglycan, etc
A. Fructose
B. Galactose
C. Sucrose
B. Galactose
Major sugar found in seminal fluid.
A. Glucose
B. Fructose
C. Galactose
D. Lactose
B. Fructose
Fructose is found in seminal plasma and in the
fetal circulation of ungulates and whales. Aldose
reductase is found in the placenta of the ewe and
is responsible for the secretion of sorbitol into
the fetal blood. The presence of sorbitol
dehydrogenase in the liver, including the fetal
liver, is responsible for the conversion of sorbitol
into fructose. This pathway is also responsible
for the occurrence of fructose in seminal fluid
Organ responsible for the majority of serine
uptake in the peripheral tissues, liver and
muscles
A. Heart
B. Brain
C. Kidneys
D. Liver
C. Kidneys
The kidney provides a major source of serine for
uptake by peripheral tissues, including liver and muscle. Branched-chain amino acids, particularly
valine, are released by muscle and taken up
predominantly by the brain
Major end product of nitrogen catabolism in
humans
A. Ammonia
B. Creatinine
C. Urea
C. Urea
Urea is the Major End Product of Nitrogen
Catabolism in Humans
Synthesis of 1 mol of urea requires 3 mol of ATP,
1 mol each of ammonium ion and of aspartate,
and employs five enzymes (Figure 28–16). Of the
six participating amino acids, N-acetylglutamate
functions solely as an enzyme activator. The
others serve as carriers of the atoms that
ultimately become urea.
substance involved in the stimulation of
protein kinase activity
a. ATP
b. cAMP
c. Calcium
d. Magnesium
b. cAMP
in prokaryotic cells, cAMP binds to a
specific protein called cAMP activator protein
(CAP) that binds directly to DNA and influences
gene expression. By contrast, in eukaryotic cells,
cAMP binds to a protein kinase called protein
kinase A (PKA), a heterotetrameric molecule
consisting of two regulatory subunits (R) that inhibit the activity of the two catalytic subunits
(C) when bound as a tetrameric complex.
ATP produced in oxidation of 1 mol of C16
fatty acid. ANS: net = 106
a. 8
b. 28
c. 80
d. 108
d. 108
The breakdown of 1 mol of palmitate,
therefore, yields a gross total of 108 mol of ATP.
However, two high-energy phosphates are used
in the initial activation step (Figure 22–3), thus
there is a net gain of 106 mol of ATP per mole of
palmitate used.
least describes KETOGENESIS
a. Fatty acids must be activated before
being catabolized
b. B-oxidation cycle generates FADH2 and
NADH
c. Long chain fatty acids penetrate inner
mitochondrial membrane
d. Conversion of fatty acid to Acyl-CoA
requires 1 high energy Phosphate
c. Long chain fatty acids penetrate inner
mitochondrial membrane
Long-chain acyl-CoA (or FFA) cannot
penetrate the inner membrane of mitochondria.
In the presence of carnitine, however, carnitine
palmitoyltransferase-I, located in the outer
mitochondrial membrane, transfers the long-
chain acyl group from CoA to carnitine, forming
acylcarnitine and releasing CoA.
Acetyl-CoA synthetases are NOT found in
this structure:
a. Peroxisomes
b. Outer mitochondrial membrane
c. Endoplasmic reticulum
d. Cytosol
d. Cytosol
Acyl-CoA synthetases are found in the
endoplasmic reticulum, peroxisomes, and on
the outer membrane of mitochondria
Carnitine is formed by:
a. Lysine and methionine
b. Glycine and arginine
c. Proline and hydroxyproline
d. Aspartate and glutamate
a. Lysine and methionine
Trimethyllysine and γ-butyrobetaine
hydroxylases are required for the synthesis of
carnitine. Trimethyllysine from methionine and
lysine.
Beta oxidation requires all these, except:
a. NAD
b. CoA
c. NADP
d. FAD
c. NADP
Each step in fatty acid oxidation involves
acyl-CoA derivatives, is catalyzed by separate
enzymes, utilizes NAD+ and FAD as coenzymes,
and generates ATP. It is anaerobic process,
requiring the presence of oxygen.
Ketone bodies are synthesized in:
a. Brain
b. Adipose tissue
c. Liver
d. Muscles
c. Liver
When this pathway is proceeding at a high
rate, three compounds, acetoacetate, D-3-
hydroxybutyrate, and acetone, known
collectively as ketone bodies, are produced in
the liver.
Which of the following are TRUE regarding
beta-oxidation?
a. Requires beta-ketoacyl CoA as substrate
b. Forms CoA thioesterase
c. Requires GTP for its activity
d. Yields acetyl-CoA as product
d. Yields acetyl-CoA as product
Acetyl-CoA is both the endpoint of fatty
acid catabolism and the starting substrate for the
fatty acid synthesis,
Rate-limiting step for the synthesis of free
fatty acid.
a. Acetyl-CoA carboxylase
b. Carbamoyl PhosphateSynthetase I
c. Acetyl-CoA decarboxylase
d. Carbamoyl Phosphate Synthetase II
a. Acetyl-CoA carboxylase
Acetyl-CoA carboxylase is the most
important enzyme in the regulation of
lipogenesis.
NADPH is from what pathway
Pentose phosphate pathway
The main source of NADPH for lipogenesis
is the pentose phosphate pathway. The oxidative
reactions of the pentose phosphate pathway are
the chief source of hydrogen required for the
synthesis of fatty acids.
True of Fatty acid multienzyme complex
except
a. Dimer composed of 2 identical monomer
b. C-terminal a-ketoacyl
b. C-terminal a-ketoacyl
The complex is
a dimer of two identical polypeptide monomers
in which six enzymes and the ACP are linked in
the primary structure in the sequence shown. X-
ray crystallography of the three-dimensional structure has demonstrated that the two
monomers in the complex are arranged in an X-
shape.
N terminal: Ketoacyl synthase
C terminal: thioesterase
Elongation of fatty acid occur in what organ
Endoplasmic reticulum
Cofactor of acetyl coa to malonyl coa
biotin
Acetyl-Coa carboxylase
has a requirement for the B vitamin biotin and is
a multienzyme protein containing biotin, biotin
carboxylase, biotin carboxyl carrier protein, and
carboxyl transferase.
Inc concentrations of sphingomyelins
Niemann-Pick disease
Farber Disease
Ceramidase
Phospholipase A2 removes FA synthesis
from lecithin to form
a. Phosphatidic acid
b. Lysolecithin or lysophosphatidylcholine
c. Lecithin granules
d. Glyceryl phosphate
b. Lysolecithin or lysophosphatidylcholine
Serves as precursor…. glycerol moeity….
glycerol ether phospholipids like plasmalogens
& PAF
Dihydroxyacetone phosphate
Phosphoglycerols
containing an ether link (-C-O-C-). the best
known of which are plasmalogens and PAF, are
derived from the dihydroxyacetone phosphate.
Deficiency in lung surfactant causes
respiratory distress syndrome. Which
phospholipid is most likely involved?
Dipalmitoyl-phosphatidylcholine
Lung surfactant is mainly
composed of lipids with some proteins and
carbohydrates and prevents the alveoli from
collapsing. The phospholipid dipalmitoyl
phosphatidylcholine decreases surface tension
at the air-liquid interface and thus greatly
reduces the work of breathing.
38.Triacylglycerols in plasma lipoproteins are
hydrolyzed by
a. Lipoprotein lipase
b. Pancreatic lipase
c. Lingual lipase
d. Colipase
a. Lipoprotein lipase
Triacylglycerols of Chylomicrons & VLDL
Are Hydrolyzed by Lipoprotein Lipase toForm
Remnant Lipoproteins. While, hepatic lipase is
involved in chylomicron remnant and HDL
metabolism.
VLDL apolipoproteins include:
B-100, C-1, C-2, C-3
40.Which of the following has the least
cholesterol
a. Milk
b. Meat
c. Cheese
d. Butter
a. Milk
Regulation of intracellular cholesterol is
upregulated by this transcription factor
a. HMG CoA
b. SREBP
c. Sterol proteolytic enzymes
d. HMG CoA reductase
b. SREBP
Acetoacetyl-CoA condenses with a
further molecule of acetyl-CoA catalyzed by
HMGCoA synthase to form HMG-CoA, which is
reduced to mevalonate by NADPH in a reaction
catalyzed by HMG-CoA reductase. This last
step is the principal regulatory step in the
pathway of cholesterol synthesis and is the site
of action of the most effective class of the cholesterol-lowering drugs, the statins, which
are HMG-CoA reductase inhibitors.
Not apolipoprotein function
a. Enzyme inhibitor
b. Form part of lipoprotein structure
c. Enzyme cofactor
d. Control lipolysis
d. Control lipolysis
Apolipoproteins carry out several roles:
(1) they can form part of the structure of the
lipoprotein; (2) they are enzyme cofactors, for
example, C-II for lipoprotein lipase, A-I for
lecithin:cholesterol acyltransferase (LCAT), or
enzyme inhibitors, for example, apo A-II and
apo C-III for lipoprotein lipase, apo C-I for
cholesteryl ester transfer protein; and (3) they
act as ligands for interaction with lipoprotein
receptors in tissues.
True of the alcohol fatty liver:
The fat accumulation in the liver is
caused by a combination of impaired fatty acid
oxidation and increased lipogenesis, which is
thought to be due to changes in the
[NADH]/[NAD+] redox potential in the liver,
and also to interference with the action of
transcription factors regulating the expression
of the enzymes involved in the pathways
Least likely true of phenylketonuria
a. Diet low in phenylalanine can prevent
mental retardation of PKU
b. Type 1 and 2 – defects in
dihydrobiopterin reductase
c. Type 3 and 4 – defects in
dihydrobiopterin biosynthesis
d. DNA probe facilitate prenatal
diagnosis of defects
Hyperphenylalaninemias arise from
defects in phenylalanine hydroxylase, (type I,
classic phenylketonuria[PKU], frequency 1 in
10,000 births), in dihydrobiopterin reductase
(types II and III), or in dihydrobiopterin
biosynthesis (types IV and V)
Precursor of thyroxine
a. Glutamate
b. Tyrosine
c. Phenylalanine
d. Serine
b. Tyrosine
The amino acid tyrosine is the starting
point in the synthesis of both the
catecholamines and thyroid hormones
tetraiodothyronine (thyroxine; T4) and
triiodothyronine (T3)
Not a catecholamine
a. Dopamine
b. Noradrenaline
c. Adrenaline
d. Histamine
d. Histamine
Three amines—dopamine,
norepinephrine, and epinephrine—are
synthesized from tyrosine in the chromaffin
cells of the adrenal medulla.
The free fatty acid in the blood are:
A. Mainly bound to b lipoprotein
B. Stored as fat droplets
C. Bound to serum albumin
D. Metabolically inactive
C. Bound to serum albumin
Release of free fatty acids into the plasma, where
they are found combined with serum albumin
The beta-oxidation of odd-carbon fatty acid
chain gives which substrate?
A. Acetyl CoA
B. Proprionyl CoA
C. Succinyl CoA
D. Malonyl CoA
B. Proprionyl CoA
Propionyl-CoA instead of acetylCoA is used as
the primer for the synthesis of long-chain
fatty acids with an odd number of carbon atoms.
Which of the following has the correct order
from lowest to highest density?
A. Chylomicrons, VLDL, IDL, LDL
B. LDL, IDL, VLDL, Chylomicrons
C. Chylomicrons, IDL, VLDL, LDL
D. VLDL, IDL, LDL, Chylomicrons
A. Chylomicrons, VLDL, IDL, LDL
LCAT activity is associated with which
lipoprotein complex?
A. IDL
B. Chylomicrons
C. VLDL
D. HDL
D. HDL
HDL3, generated from discoidal HDL by the
action of LCAT, accepts cholesterol from the
tissues via the SR-B1 and the cholesterol is then
esterified by LCAT, increasing the size of the
particles to form the less dense HDL2.
Which lipoprotein removes cholesterol from
the body?
A. IDL
B. Chylomicrons
C. VLDL
D. HDL
D. HDL
In the tissues, on the other hand, SR-B1 mediates
the acceptance of cholesterol effluxed from the
cells by HDL, which then transports it to the liver
for excretion via the bile (either as cholesterol or after conversion to bile acids) in the process
known as reverse cholesterol transport.
Which of the following best describes
cholesterol?
A. Its main metabolic end product is bile acid
B. Excretion is through feces
C. A meal rich in unsaturated fats will help lower
cholesterol plasma levels in blood
D. Squalene is the hydrocarbon formed in
cholesterol synthesis
C. A meal rich in unsaturated fats will help lower
cholesterol plasma levels in blood
One of the mechanisms by which unsaturated
fatty acids lower blood cholesterol levels is by
the upregulation of LDL receptors on the cell
surface
Which of the following lipoproteins would
contribute to a measurement of plasma
cholesterol in a normal individual following a 12
hr fast?
A. Chylomicrons
B. HDL
C. LDL
D. Both LDL and VLDL
D. Both LDL and VLDL
Committed step in cholesterol synthesis:
mevalonate from HMG Co
Triacylglycerols in plasma lipoproteins are
hydrolyzed by
A. Lipoprotein lipase
B. Pancreatic lipase
C. Lingual lipase
D. Colipase
A. Lipoprotein lipase
Triacylglycerols of Chylomicrons & VLDL Are
Hydrolyzed by Lipoprotein Lipase to Form
Remnant Lipoproteins
Conversion of acetyl coa to malonyl coa
requires
A. H2O
B. NADPH
C. Biotin
D. Folic acid
C. Biotin
Bicarbonate as a source of CO2 is required in the
initial reaction for the carboxylation of acetyl-
CoA to malonyl-CoA in the presence of ATP and
acetyl-CoA carboxylase. This enzyme has a major
role in the regulation of fatty acid synthesis (see
below). Acetyl-CoA carboxylase has a
requirement for the B vitamin biotin and is a
multienzyme protein containing biotin, biotin
carboxylase, biotin carboxyl carrier protein, and
a carboxyl transferase, as well as a regulatory
allosteric site.
Not apolipoprotein function
A. Enzyme inhibitor
B. Form part of lipoprotein structure
C. Enzyme cofactor
D. Control lipolysis
D. Control lipolysis
Apolipoproteins carry out several roles:
(1) they can form part of the structure of the
lipoprotein
(2) they are enzyme cofactors or enzyme
inhibitors
(3) they act as ligands for interaction with
lipoprotein receptors in tissues
Amino acid that can be converted to
tyrosine if with ample supply
A. Leucine
B. Phenylalanine
C. Arginine
D. Glycine
B. Phenylalanine
Phenylalanine hydroxylase converts
phenylalanine to tyrosine. If the diet contains
adequate quantities of the nutritionally essential
amino acid phenylalanine, tyrosine is
nutritionally nonessential.
True for Urea Synthesis: Has 5 steps
Disorder of branched chain amino acid:
maple syrup urine disease (branched-chain ketonuria, or MSUD)
Branch chain Amino Acid:
isoleucine, leucine, and valine
THE INITIAL REACTIONS ARE COMMON TO ALL
THREE BRANCHED-CHAIN AMINO ACIDS
The first three reactions of the catabolism of
isoleucine, leucine, and valine are analogous to
reactions of fatty acid catabolism.
Defective enzyme in classic
hyperphenylalaninemias
A. Tyrosine aminotransferase
B. Phenylalanine hydroxylase
C. Homogentisate oxidase
D. Tryptophan pyrrolase
B. Phenylalanine hydroxylase
Hyperphenylalaninemias arise from defects in
phenylalanine hydroxylase, type I, classic
phenylketonuria [PKU].
Precursor of allergic factor and gastric
secretion (histamine)
A. Glutamine
B. Histidine
C. Phenylalanine
D. Cysteine
B. Histidine
Decarboxylation of histidine to histamine is
catalyzed by the pyridoxal 5′-phosphate-
dependent enzyme histidine decarboxylase
Precursor of norepinephrine
A. Cysteine
B. Tryptophan
C. Serine
D. Tyrosine
D. Tyrosine
Neural cells convert tyrosine to epinephrine and
norepinephrine.
Not involved in creatine synthesis
A. Glycine
B. Serine
C. Arginine
D. Methionine
B. Serine
Glycine, arginine, and methionine all participate
in creatine biosynthesis.
Matching Type
A. Fumarylacetoacetate hydrolase
B. tyrosine aminotransferase
C. cystathionine B synthase
D. p-hydroxyphenylpyruvate hydroxylase
E. histidine ammonia lyase
- Homocystinuria: cystathionine B synthase
- Type 1 tyrosinemia: Fumarylacetoacetate
hydrolase - Type 2 tyrosinemia: tyrosine
aminotransferase - Neonatal tyrosinemia: p-
hydroxyphenylpyruvate hydroxylase - Histidinemia: histidine ammonia lyase
A. Glucogenic
B. Ketogenic
C. Both
- Alanine: Glucogenic
- Lysine: Ketogenic
- Leucine: Ketogenic
- Tyrosine: Both
- Valine: Glucogenic
Oxidation of palmitic acid (C16) involves ______
rounds of B-oxidation and yields _____molecules of
acetyl-CoA.
8, 8
7, 8
7, 7
16, 8
7, 8
seven cycles needed for the breakdown of the C16 fatty
acid, palmitate, to acetyl-CoA (7 × 4 = 28). A total of 8 mol of
acetyl-CoA is formed, and each gives rise to 10 mol of ATP on oxidation in the citric acid cycle, making 8 × 10 = 80 mol
Which of the following yields the most energy per
gram when oxidized?
protein
starch
fat
glycogen
fat
fatty acids yield the most ATP on an energy per gram basis, when they are completely oxidized to
Very long chain fatty acids (C20, C22) are oxidized in
which type of organelle?
peroxisomes
lysosomes mitochondria
endoplasmic reticulum
peroxisomes
Peroxisomes Oxidize Very Long Chain FAs
A modified form of β-oxidation is found in peroxisomes and
leads to the formation of acetyl-CoA and H2O2 (from the
flavoprotein-linked dehydrogenase step), which is broken
down by catalase. Thus, the dehydrogenation in peroxisomes
is not linked directly to phosphorylation and the generation of
ATP. The system facilitates the oxidation of very long chain fatty acids (eg, C20, C22)
Which of the following statements BEST DESCRIBES
the regulation of ketogenesis?
- Overproduction of ketone bodies is due to excessive
carbohydrates.
- This is the outcome of excessive utilization of
fatty acids to meet the energy requirements.
- Glucagon inhibits ketogenesis while, insulin
stimulates it.
- High concentration of oxaloacetate favors
ketogenesis
- This is the outcome of excessive utilization of
fatty acids to meet the energy requirements
Regulation of Ketogenesis happens in 3 crucial steps
Excessive utilization of FFA leads to production of more acetylCoA entering the ketogenic pathway. (Figure 22-9)
High concentration of oxaloacetate favors which
pathway?
Glycolysis HMP shunt
TCA cycle
Glycogenolysis
TCA cycle
condensation of acetyl-CoA with oxaloacetate in the citric acid cycle within mitochondria,
Ketone bodies are synthesized in:
muscles
adipose tissue
brain
liver
liver
KETOGENESIS OCCURS WHEN THERE IS A HIGH RATE OF FATTY ACID OXIDATION IN THE LIVER
This lipid is derived from free fatty acids through
esterification after an uptake by the liver.
a. cholesterol
b. triacylglycerol
c. sphingolipid
d. lipoprotein
a. cholesterol
Chylomicron remnants are taken up by the liver by
receptor-mediated endocytosis, and the
cholesteryl esters & triacylglycerol are hydrolyzed
and metabolized. Triacylglycerol is composed of
three fatty acids esterified to a glycerol molecule
Which is not a characteristic feature of the
fatty acid synthase multienzyme complex?
a. dimer of 2 polypeptide monomer
b. complex arranged in an X-shape as identified
by an X-ray crystallography
c. the enzyme at the primary structure at the
C-terminus is ketoacyl synthase
d. has an acyl carrier protein attached to the
primary structure
c. the enzyme at the primary structure at the
C-terminus is ketoacyl synthase
the enzyme at the primary structure at the C-terminus is thioesterase
Ketone bodies are formed from acetyl-CoA which is
directly produced from:
a. alanine
b. lysine
c. phenylalanine
d. isoleucine
b. lysine
In extramitochondrial fatty acid synthesis, one of
the following cofactors or their derivatives is
necessary for the conversion of acetyl CoA to
malonyl CoA
a. FMN
b. biotin
c. FAD
d. ACP
b. biotin
Acetyl CoA carboxylase converts acetyl CoA to
malonyl CoA. It has a requirement for the B vitamin
biotin and is a multienzyme protein.
The concentration of sphingomyelins are increased
in this disease entity.
a. Fabrile disease
b. Fabry disease
c. Niemann-Pick disease
d. Gaucher disease
c. Niemann-Pick disease
Fabry disease - alpha-galactosidase
Niemann-Pick disease - sphingomyelinase
Gaucher disease - beta-galactosidase
What is the correct ordering of serum lipoprotein
from the greatest to lowest density?
a. chylomicron, LDL, IDL, VLDL
b. IDL, chylomicron, LDL, VLDL
c. LDL, IDL, VLDL, chylomicron
d. VLDL, IDL, LDL, chylomicron
c. LDL, IDL, VLDL, chylomicron
Densities:
LDL - 1.019 - 1.063
IDL - 1.006 - 1.019 VLDL - 0.95 - 1.006 Chylomicron - <0.95
This pathway servees as the main source of NADPH
for lipogenesis
A. Beta oxidation
B. Gluconeogenesis
C. Citric Acid Cycle
D. HMP shunt
D. HMP shunt
The main source of NADPH for lipogenesis is the Pentose Phosphate Pathway. PPP is also known as Hexose monophosphate (HMP) shunt
The primer used for the synthesis of long-chain fatty
acids with odd number of carbon atoms
A. Malonyl CoA
B. Acetyl CoA
C. Propionyl CoA
D. Acyl CoA
C. Propionyl CoA
The Acetyl-CoA used as a primer formscarbon atoms 15 and
16 of palmitate. th addition of all the subsequent C2 units is
via the malonyl-CoA. Propionyl CoA instead of acetyl CoA is
used as a primer for the synthesis of long chain fatty acids with an odd number of carbon atoms, which are found
particularly in ruminant fat and milk
Which of the ff is the 2nd step of lipogenesis?
A. Provision of acetyl-CoA and NADPH
B. Transport of acetyl-CoA from the mitochondria to
the cytosol
C. Reactions of synthesis using fatty acid
synthase complex
D. Carboxylation of acetyl-CoA to malonyl-CoA
C. Reactions of synthesis using fatty acid
synthase complex
Production of Malonyl-CoA is the initial & controlling step in
fatty scid synthesis. After the formation of malonyl-CoA, fatty acids are formed by the fatty acid synthase enzyme
complex.
Best describes the regulation of acetyl-CoA
carboxylase
A. Inactivated by cysteine group
B. Activated by citrate
C. Tricarboxylate transporter transports citrate from
cytosol to mitochondria
D. Inactivation is promoted by phosphorylation of
the enzyme
B. Activated by citrate
lipogenesis. It is an allosteric enzyme and is activated by
citrate, which increases in concentration in the well-fed state
and is an indicator of a plentiful supply of acetyl-CoA (Please recheck since option D is also in p.221)
rechecked: both answers are considerable.
Which of the ff lipoproteins would contribute to a
measurement of plasma cholesterol in a normal
individual ff a 12-hr fast?
A. Both VLDL and LDL
B. VLDL
C. LDL
D. Chylomicrons
A. Both VLDL and LDL
Alcoholic fatty liver is best described by this statement
A. The concomitant gout in these patients is due to
hypolacticacidemia
B. May be caused by decreased lipogenesis &
impaired fattyacid oxidation
C. There is excess production of NAD
D. (+) oxidation of ethanol by alcohol
dehydrogenase
D. (+) oxidation of ethanol by alcohol
dehydrogenase
Oxidation of ethanol by alcohol dehydrogenase leads to
excess production of NADH, which competes with reducing
equivalents from other substrates, including fatty acids, for
the respiratory chain This inhibits their oxidation and causes
increased esterification od fatty acids to form triacylglycerol,
resulting in fatty liver disease.
A. Hyperlacticacidemia decreases excretion of uric acid,
aggravating gout
B. Caused by impaired fatty acid oxidation and increased lipogenesis
C. Excess production of NADH
Lipase present in the stomach cannot hydrolyze fats
owing to its
A. Acidity
B. Esterification property
C. Neutrality
D. Alkalinity
A. Acidity
Digestion of Fats Occurs Mainly in the Small Intestine. A small amount of triglycerides is digested in the
stomach by lingual lipase secreted by lingual glands in the mouth and swallowed with the saliva. This amount of
digestion is less than 10 percent and is generally unimportant.
Instead, essentially all fat digestion occurs in the
small intestine as follows.
Triacylglycerol present in the plasma lipoproteins
are hydrolyzed by:
A. Colipase
B. Lingual lipase
C. Pancreatic lipase
D. Lipoprotein lipase
D. Lipoprotein lipase
A 25 y.o female has been diagnosed with lecithin:
cholesterol acyltransferase(LCAT) deficiency. In which
of the ff reactions LCAT is involved? A. uptake of cholesterol from liver cells
B. converting cholesterol to cholesterol esters
C. hydrolysis of HDL
D. transfer of cholesterol esters from HDL to VDL
B. converting cholesterol to cholesterol esters
Regulation of intracellular cholesterol is up regulated
by this transcription factor
A. SREBP
B. HMG-CoA
C. Na/K+ ATPase
D. Sterol proteolytic enzymes
A. SREBP
Match the following:
A. inhibits Tricorboxylate transporter
B. Stimulates acetyl coA carboxylase
C. inhibits acetyl coA carboxylase
D. malonyl coA
E. ATP dependent
F. palmitic acid
Acetyl coa carboxylase - D
Insulin - B
Glucagon - C
Thioesterase - A
Acyl- coA - F
Match the following:
A. Zellweger syndrome
B. RDS
C. Retinitis pigmentosa
D. Gaucher`s disease
E. Krabbe Disease
F. Farber Disease
DHA - C
Dipalmitoyl phosphatidylcholine - B
B-galactosidase - E
Ceramidase - F
Very long chain fatty acids - A
Which of the following proteins or
enzymes that when deficient, can cause
mutation implied by the chronic granulomatous disease
A. NADPH oxidase
B. Myeloperoxidase
C.
D. Glutathione peroxidase
A. NADPH oxidase
Which of the ff. Metabolic pathways is
crucial to the red blood cells as it
supplies reducing energy to the cell
A. Glycolysis
B. Oxidative phosphorylation
C. Pentose phosphate pathway
D. Citric acid cycle
C. Pentose phosphate pathway
This pathway is the alternative source of
energy (ATP) of platelets.
A. Glycolysis
B. Fatty acid beta oxidation
C. Pentose phosphate pathway
D. Ketogenesis
B. Fatty acid beta oxidation
Glycolytic enzymes in a eukaryotic cell
are located in the?
Cytosol
This statement LEAST LIKELY describes
glycolysis:
A. ADP is phosphorylated to ATP via
substrate level phosphorylation
B. The pathway oxidizes two moles of NADH to NAD+ for each mole of glucose
that enters
C. The pathway does not require oxygen
D. The pathway requires two moles of
ATP to get started catabolizing each
mole of glucose
B. The pathway oxidizes two moles of NADH to NAD+ for each mole of glucose that enters
Which of the following enzymes is the
major energy generating step during
glycolysis
A. Phosphofructokinase
B. Pyruvate kinase
C.Glyceraldehyde-3-Phosphate
D. Phosphoglycerate kinase
C.Glyceraldehyde-3-Phosphate
Glucose from the breakdown of glycogen
through hydrolysis is obtained in what
organ?
A. Liver
B. Muscles
C. Kidneys
D. Pancreas
A. Liver
In glycogen synthase reaction, precursor
of glycogen:
A.Glucose-6-phosphate
B.UTP-glucose
C.Glucose-1-phosphate
D.UDP-glucose
D.UDP-glucose
he first irreversible step of glycolysis
is catalyzed by this enzyme
a. Hexokinase
b. Phosphofructokinase
c. Glucokinase
d. Pyruvate kinase
a. Hexokinase
Cleave of your fructose 1,6
bisphosphate yields
a. Aldose, ketose
b. 2 aldose
c. 2 ketose
d. Only a ketose
a. Aldose, ketose
Aldose DHAP ketose G3P
Substrate used in the last step of
glycolysis:
A. Pyruvate
B. GA3P
C. 1,3-BPG
D. PEP
D.PEP( phosphoenolpyruvate)
Pyruvate, the end product of glycolysis,
enters the citric acid cycle after is has
been converted to
A. Acetic acid
B. Lactic acid
C. Acetaldehyde
D. Acetyl-CoA
D. Acetyl-CoA
Carrier protein which transports pyruvate
through the mitochondrial matrix
A. NADH
B. Coenzyme A
C. NADPH
D. Succinyl CoA
B. Coenzyme A
BEST DESCRIBES the rate-limiting
enzymes of glycogenolysis.
A. Named glycogen synthase
B. Catalyze the phosphorylitic cleavage
of the 1->4 linkages of glycogen to G3P
C. Requires glycogenesis as its
coenzyme
D. Has different isoenzyme encoded by
different genes
D. Has different isoenzyme encoded by
different genes
Glycolytic enzymes in eukaryotic cells
are located in
A. Plasma membrane
B. Mitochondrial matrix
C. Cytosol
D. Intermembrane space
C. Cytosol
LESS LIKELY describes glycolysis:
A. ADP is phosphorylated to ATP at
substrate level phosphorylation
B. Pathway oxidizes 2 NADH to NAD+
for each mole of glucose that enters
C. Does not require oxygen
D. Pathway required 2 ATP to start
catabolizing each mole of glucose
B. Pathway oxidizes 2 NADH to
NAD+ for each mole of glucose
that enters
*Should be reduces NAD+ to NADH
Enzyme involved in the major energy
generating step in glycolysis:
A. Phosphofructokinase
B. Pyruvate kinase
C. GA3P
D. Phosphoglycerate kinase
C. GA3P
Glucose, from glycogen through
hydrolysis, can be found in
A. Liver
B. Muscle
C. Kidney
D. Pancreas
A. Liver
What is the precursor of glucose
A. Glucose 1 phosphate
B. UDP- glucose
C. Glucose-6 phosphate
D. Glucose-6 phosp
C. Glucose-6 phosphate
In the liver, cAMP independent activation
of glycogenolysis needs the following
hormones, EXCEPT:
A. Epinephrine
B. Angiotensin II
C. Glucagon
D. Vasopressin
C. Glucagon
Glycogenin is needed to create an initial
short glycogen chain. These amino acid
residues serves as an anchor for the
terminal chain of glycogen:
A. Serine
B. Tyrosine
Glycogenin is needed to create an initial
short glycogen chain. These amino acid
residues serves as an anchor for the
terminal chain of glycogen:
A. Serine
B. Tyrosine
C. Glycine
D. Leucine
B. Tyrosine
What’s faster when needing glucose
A. Gluconeogenesis
B. Gluconeogenesis
C. Glycogenolysis - KANI
D. Glycolysis
C. Glycogenolysis
Makes up the bond in glycogen branches
A. Phospodiester
B. Covalent
C. 1,4-glycosidic
D. 1,6-glycosidic
D. 1,6-glycosidic
which enzyme is activated by glucagon
a. glycogen synthase
b. phosphoenolpyruvate carboxykinase
c. phosphofructokinase 1
d. hexokinase
b. phosphoenolpyruvate carboxykinase
The metabolic function of PPP is
a. ADP biosynthesis
b. i forgot huu saarry
c. oxidation-reduction formation of h20
d. generate nadph and pentoses for the
biosynthesis of fatty acid and nucleic acid
d. generate nadph and pentoses for the
biosynthesis of fatty acid and nucleic acid
LEAST likely describes PPP
A. Occurs in the cytosol
B. Oxygenation occurs by dehydration of
NAD+ to act as oxygen acceptor
C. Does not require ATP
D. Has 2 stages, irreversible and
substrate
B. Oxygenation occurs by
dehydration of NAD+ to act as
oxygen acceptor
increase in insulin release
1. Fed
2. Fasting
- Fed
increase in glycogen synthesis
1. Fed
2. Fasting
- Fed
increase in glucagon release
1. Fed
2. Fasting
- Fasting
inhibition of lipogenesis
1. Fed
2. Fasting
- Fasting
gluconeogenesis
1. Liver
2. Kidney
- Liver
- Kidney
Beta oxidation
1. Liver
2. Kidney
- Liver
Plasma Proteins
1. Liver
2. Kidney
- Liver
Glycerol kinase
1. Liver
2. Kidney
- Liver
- Kidney
Morse type: Cause and effect
A. Both statements are true and are
related
B. Both statements are true but unrelated
C. Statement 1 is true, statement 2 is
false
D. Statement 1 is false, statement 2 is
true
E. Both statements are false
A - Water soluble products of digestion are
transported directly to the liver via
hepatic portal vein because the liver
regulates the concentration of glucose
and amino acids to other tissues
A - In fasting state, glucose is spared for rbc
and brain because they primarily use
glucose as metabolic fuel
D - Most amino acids undergo glycolysis
from TAG because products of digestion
are used to synthesize complex
macromolecules
A - ATP is the energy currency of the cell
because of its high energy potential
where ATP becomes
A - Exergonic reaction, spontaneous energy,
loss of free energy BECAUSE negative
free energy
