Transcript Biochemistry review

(Bio)Chemistry Section
1. Which pair of enzymes listed below is unique to
gluconeogenesis?
a. pyruvate kinase & pyruvate carboxylase
b. phosphoenolpyruvate carboxykinase &
pyruvate carboxylase
c. fructose bisphosphatase & phosphofructokinase
d. pyruvate dehydrogenase & glucose-6-phosphatase
GLYCOLYSIS
Glucose  Glucose 6-P
Glucokinase /hexokinase
GLUCONEOGENESIS
Glucose 6-P glucose
Glucose-6 phosphatase
F-6-P  F-1,6-BP
Phosphofructokinase
F-1,6-BP  F-6-P
PEP  Pyruvate
Pyruvate kinase
Pyruvate  oxaloacetate
Pyruvate carboxylase
Fructose-1,6-bisphosphatase
Oxaloacetate PEP
PEP carboxykinase
2. Which two polysaccharides contain the same
type of bonds?
a. cellulose and amylose
b. amylopectin and glycogen
c. glycogen and cellulose
d. amylose and amylopectin
Polysaccharides
Carb
monomers
Starch
hydrolyzed
Polymer of D-glucose
--amylose
--amylopectin branches ~12 res.
GlycogenD-glucose
branches ~8 res
Cellulose D-glucose: found in plants β1-4
Inulin
bonds
α-amylase
α1-4
α1-4 & α1-6
α1-4 & α1-6
into glucose,
maltose,
isomaltose
α-amylase
cellulase
D-fructose: found in roots and tubers of lotus, artichokes
and dandilions
Dietary Fibers
Mixture of polysaccharides and non-carbohydrates
3. Which glycolytic enzyme catalyzes a
substrate level phosphorylation?
a. glucokinase
b. phosphofructokinase
c. phosphoglycerate kinase
d. hexokinase
Enzyme
Reaction
catalyzed
Pathway
Molecule
generated
Phosphoglycerate
kinase
1,3-BPG to 3PG
Glycolysis
ATP
Pyruvate kinase
PEP to pyruvate
Glycolysis
ATP
Succinyl-CoA
synthetase
Succinyl-CoA to
succinate
Kreb’s cycle
GTP
ATP synthase
ADP to ATP
ETC
ATP
Creatine
(phospho)kinase
Phosphocreatine to Skeletal
creatine
muscle and
brain
ATP
4. An example of food that is an excellent
source of soluble fiber is
a. wheat bran cereal
b. brown rice
c. whole wheat bread
d. oatmeal
5. Which polysaccharide has the highest
proportion of α-1,4-glycosidic linkages?
a. starch
b. amylopectin
c. glycogen
d. amylose
6. Which sugar is has a C-2 carbonyl carbon?
a. fructose
b. galactose
c. glucose
d. mannose
GLUCOSE
6 carbon carbohydrates
(hexoses)
FRUCTOSE
Aldoses
D-glucose
D-galactose
D-mannose
Ketose
D-fructose
7. Which molecule is not essential for the
complete degradation of glycogen in muscle
and liver?
a. inorganic phosphate
b. glycogen phosphorylase
c. glycogenin
d. glycogen debranching enzyme
Key enzymes:
1. Glycogen phosphorylase
Breaks α14 bonds
of glucose in glycogen to form G—1—P
2. Glucan transferase
When a glycogen branch
has been reduced to 4 residues, it removes 3 and
adds to an existing glycogen polymer branch in
α14 linkage
3. Debranching enzyme
Removes final α16 of last glucose residue from
stump to release glucose
Glycogenesis
Key enzymes:
1. Phosphoglucomutase
Isomerizes G—6—P to G—1—P
2. Glycogen synthase
Attaches glucose unit
(from UDP-Glucose) to an existing primer in α14
3. Branching enzyme a) Removes ~6 glucose chain
from growing glycogen polymer
b) attaches to a nearby glycogen in α16
Glycogenin: needed for synthesis of glycogen primer (‘glycogenesis’)
8. Which glucose transporter is saturated or
close to saturation only after a carbohydrate
rich meal?
a. GLUT-1
b. GLUT-2
c. GLUT-3
d. GLUT-4
GLUT-1:
Passive-facilitative
Brain, kidney, placenta,
colon, RBCs
GLUT-2:
Passive-facilitative
Liver, pancreatic β cells, kidney
Intestineblood (all mono-)
GLUT-3:
Passive-facilitative
Brain, kidney, placenta
GLUT-4:
ACTIVE
Heart, skeletal ms., adipose
Insulin-stimulated transporter
for active uptake of glucose
GLUT-5:
Passive-facilitative
Intestine
For uptake of pentoses
For hexoses when [high]
9. Which of the following is NOT considered a
reducing sugar?
a. glucose
b. fructose
c. sucrose
d. lactose
Monosaccharides have free
aldehyde and ketone groups
10. What are carbohydrates that consist of
long disaccharide repeats and are important
components of connective tissue called?
a. peptidoglycan
b. proteoglycans
c. glycogen
d. glycosaminoglycans
Glycosaminoglycans: polymers of carbohydrate
derivatives, especially amino sugars and uronic acids
(ex: hyaluronic acid, chondroitin sulfate and heparin
sulfate)
Peptidoglycan: small peptides with attached GAGs
generally structural components of cell walls
Proteoglycan: proteins with attached GAGs
Glycogen: storage form of glucose in animals
11. Conversion of glucose into carbon dioxide
and passage of its electrons to molecular
oxygen represents the complete _____ of the
sugar
a. oxidation
b. reduction
c. phosphorylation
d. destruction
Think:
“oxidative phosphorylation” (ETC)
“β-oxidation” (fats)
12. The action of what enzyme during
glycolysis directly produces one molecule of
NADH per molecule of substrate
a. hexokinase D
b. phosphofructokinase-1
c. glyceraldehyde-3-phosphate
dehydrogenase
d. alpha-ketoglutarate dehydrogenase
ATP
ADP
13. An abundance of what substance will
inhibit some of the enzymes of the citric acid
cycle?
a. adenosine diphosphate
b. acetyl-coenzyme A
c. NADH
d. glucose
Isocitrate
ENZYME
Citrate Synthase
ACTIVATOR
INHIBITOR
High
NAD/NADH
High ADP/ATP
High ATP/ ADP
α-ketoglutarate
dehydrogenase
CoASH, pyruvate,
high ADP/ATP
Succinate
thiokinase
/dehydrogenase
Mg2+
Fatty acids, ketone
bodies
High NADH/NAD
Oxaloacetate
Isocitrate
Dehydrogenase
High ATP/ ADP high
NADH/NAD
14. What is the major source of energy fuel in
the average human diet?
a. carbohydrates
b. ethanol
c. fats
d. proteins
55% of kcal
30% of kcal
15% of kcal
15. Starch is the most common digestible
polysaccharide in plants and exists mainly as
amylose and amylopectin. These polymers
are composed of which basic residue?
a. D-fructose
b. D-galactose
c. D-glucose
d. D-ribose
… and in α1-4 and α1-6 linkages
16. Which of the following forms of dietary
fiber is insoluble
a. cellulose
b. gum
c. mucilages
d. pectin
Dietary Fibers: intrinsic and intact in natural foods.
Mixture of un-digestible polysaccharides and noncarbohydrate compounds
Cellulose
 Hemicellulose
 Pectin
 Lignin
 Mucilage
 Glycoprotein
 Phytic acid
 Waxes

β14 glucose units
Linear D-xylose w/ side chains
Soluble polymer of galacuronic acid
Methoxy-phenol polymers
Sugar acid polymer and galactan mix
Extensin is the major form
Inositol hexaphosphate, chelating
Esters of fatty acids and alcohols
17. The hydrolysis of lactose by lactase
produces equimolar amounts of which to
monosaccharides?
a. fructose and glucose
b. fructose and galactose
c. galactose and glucose
d. glucose and glucose
Sugar
monomers
Maltose
Dimer of D-glucose (“glucan”) α1-4
Isomaltose
Dimer of D-glucose
Sucrose
D-glucose & D-fructose
Lactose
D-glucose & D-galactose
bonds
hydrolyzed
maltase
α1-4
α1-2
isomaltase
sucrase (invertase)
β1-4
lactase
Cellobiose
Dimer of D-glucose
β1-4
cellulase (bacteria)
Trehalose
Dimer of D-glucose
α1-1
trehalase (microbe)
18. Which of the following describes
glycogenin?
a. it is a protein of muscular glycogen
b. it has no enzymatic activity
c. it is attached to the nonreductive end of
glycogen
d. it has an amylo-(1,4-1,6)-transglycosylase
activity
 Used


in Glycogenesis
Primer to which first glucose residue is attached
Has transglycosylase activity
But only 1-4
(not 1-6… that’s the branching enzyme)
19. Which of the following describes glycogen?
a. it is a heteropolysaccharide
b. it is a polymer of alpha-1,4 linked residues
with alpha 1-6 branches every 24-30
residues
c. it has many more monosaccharide units
than starch
d. it is a form of stored energy in
cytoplasmic vesicles
Polysaccharides
Carb
monomers
Starch
hydrolyzed
Polymer of D-glucose
--amylose
--amylopectin branches ~12 res.
GlycogenD-glucose
branches ~8 res
Cellulose D-glucose: found in plants β1-4
Inulin
bonds
α-amylase
α1-4
α1-4 & α1-6
α1-4 & α1-6
into glucose,
maltose,
isomaltose
α-amylase
cellulase
D-fructose: found in roots and tubers of lotus, artichokes
and dandilions
Dietary Fibers
Mixture of polysaccharides and non-carbohydrates
20. Which is true of UDP-glucose
a. it is a substrate of UDP-glucose
phosphorylase
b. it contains one sugar with five carbons
and one sugar with six carbons
c. it is a substrate of the degradation of
glycogen
d. it is an allosteric activator of glycogenbranching enzyme
 UDP-glucose

Uridine-5’-diphosphate-glucose
Nucleotide
Base + ribose + phosphate
5-carbon

6-carbon
Glycogen synthase attaches glucose unit (from UDPGlucose) to an existing primer in α14
1. Glycogenesis: biosynthesis of
glycogen
Key enzymes:
1. Phosphoglucomutase
Isomerizes G—6—P to
G—1—P
2. Glycogen synthase
Attaches glucose unit
(from UDP-Glucose) to an existing primer in α14
a) Removes ~6 glucose chain
from growing glycogen polymer
b) attaches to a nearby glycogen in α16
3. Branching enzyme
21. Which is true of glycogen phosphorylase?
a. it is active in its b form (phosphorylase b)
b. it is phosphorylated by phosphoprotein
phosphatase
c. when not phosphorylated, it is activated in
the presence of glucose-6-phosphate in
the liver
d. when phosphorylated, it is inactive in the
presence of glucose
Phosphorylates
Dephosphorylates
Glycogen
synthase
Glycogen
phosphorylase
Adrenaline /
Epinephrine
Insulin
+
—
—
+
Phosphorylates
INACTIVE
Phosphorylates
ACTIVE
Dephosphorylates
ACTIVE
Dephosphorylates
INACTIVE
22. Which of the following enzymes represents
the step where the second high-energy
phosphate is invested in glycolysis?
a. pyruvate kinase
b. 3-phosphoglycerate dehydrogenase
c. phosphofrutokinase
d. pyruvate dehydrogenase
e. hexokinase
hexokinase
phosphofructokinase
ATP
ADP
Glyceraldehyde 3-P
dehydrogenase
Pyruvate kinase
Pyruvate dehydrogenase
23. The digestion of starch begins in what
location
a. in the duodenum with pancreatic amylase
b. in the mouth with salivary amylase
c. in the jejunum with maltase
d. in the colon with absorption of water
24. In the formation of a proteoglycan, which
trisaccharide is used to attach the
carbohydrates to the protein?
a. xylose-galactose-galactose
b. rhamnose-galactitol-galactitol
c. arabinose-glucose-glucose
d. trehalose-fructose-fructose
Rhamnose = plant, bacteria
Arabinose = plant
Trehalose = microbe
25. Which of the following GLUT transporters
brings in fructose?
a. GLUT-2
b. GLUT-3
c. GLUT-4
d. GLUT-5
GLUT-1:
Passive-facilitative
Brain, kidney, placenta,
colon, RBCs
GLUT-2:
Passive-facilitative
For rapid uptake
Liver, pancreatic β cells, kidney
Intestineblood (all mono-)
GLUT-3:
Passive-facilitative
Brain, kidney, placenta
GLUT-4:
ACTIVE
Heart, skeletal ms., adipose
Insulin-stimulated transporter
for active uptake of glucose
GLUT-5:
Passive-facilitative
Intestine
For uptake of pentoses
For hexoses when [high]
1. Which of the following lipids is NOT found in
eukaryotic membranes?
a. phosphatidyl inositol
b. triglycerides
c. cholesterol
d. gangliosides
Major components of cell membranes
1. Phospholipids (e.g. phosphatidyl inositol)
2. Glycosphingolipids (e.g. cerebrosides and gangliosides)
3. Cholesterol
2. Which of the following is true of Tay-Sachs
disease?
a. it is provoked by a sphingomyelinase
deficiency
b. it is transmitted by the mother
c. it promotes a specific ganglioside
accumulation, mainly in the brain and
spleen
d. it is an autosomal dominant disease

Multiple sclerosis:
 Lack of phosphoglycerols and sphingolipids in white matter
 Cholesteryl esters found in white matter
 CSF has elevated levels of phospholipids
 Deficiency of GABA

Niemann-Pick disease:
 Deficiency of sphingomyelinase


Signs: enlarged liver and spleen, MR, fatal early in life
Tay-Sach’s disease:
 Defect of hexoseaminidase  build up of gangliosides

Signs: MR, blindness, muscular weakness
3. Which is TRUE of cholesterol
a. it is present in prokaryotic membranes
b. it has a hydroxyl on its number 3 carbon
c. in the serum, it is eliminated by the
kidneys
d. it is transported in blood by albumin
a. it is present in prokaryotic membranes
present only in animals
b. it has a hydroxyl on its number 3 carbon
c. in the serum, it is eliminated by the kidneys
Eliminated as bile acids
d. it is transported in blood by albumin
Lipoprotein (e.g. LDL, HDL)
4. Which of the following is TRUE of chylomicrons
a. they are always present in the lymphatic After a meal
circulation
intestines
b. they are synthesized by the liver
c. they are enriched in esterified cholesterol triglycerides
and free fatty acid
d. in the serum, they carry apolipoproteins A,
B-48, CII and E
5. Which is TRUE of nascent high-density
lipoprotein (HDL)
a. it contains lecithin-cholesterol acyl
transferase
b. it principally functions as storage for
C&E
apolipoproteins A and E
Protein & phospholipid
c. it is rich in triglycerides
& intestines
d. it is synthesized only by the liver
6. If blood plasma levels are extremely high in
arachidonic acid, which type of supplement
listed would be useful in increasing
eicosapentaenoic acid (EPA) and
Omega 3s
docosahexanoic acid (DHA) levels?
a. glucosamine and chondroitin
b. B complex with B6, B12 and folate
c. cold water fish oil supplement
d. ADEK, the fat soluble vitamins
7. Which of the following is the carrier for
fatty acids into the inner mitochondria
a. CoA
b. FAD
c. carnitine
d. fatty acetyl-CoA

Transport of Acyl-CoA into mitochondria using carnitine
as a carrier
CPT I
CPT II
8. Odd chain fatty acid degradation leads to
the production of acetyl-CoA and what other
compound?
a. propionyl-CoA
b. malonyl-CoA
c. acetoacetyl-CoA
d. beta-hydroxybutyrate
Acyl-CoA + CoASH + FAD + NAD + H2O
Acetyl-CoA + Acyl-CoA + FADH2 + NADH
The FADH2 + NADH are further oxidized in the
electron transport chain for ATP formation
Note:
If EVEN # of carbons in fatty acid
If ODD # of carbons in fatty acid
Acetyl-CoA
Propionyl-CoA
9. Which of the following unsaturated fatty
acids is one that can be synthesized by the
liver
a. linoleic acid
b. linolenic acid
c. oleic acid
d. arachidonic acid
BAD QUESTION
LA and ALA are essential fatty acids
AA is ‘conditionally’ essential,
meaning that if you don’t get LA or
ALA in your diet, you don’t make AA
10. What is the end product of beta oxidation
of fatty acids, which feeds into the TCA
cycle?
a. pyruvate
b. oxaloacetate
c. alpha-ketoglutarate
d. acetyl-CoA
End product of glycolysis
Intermediates of the
Kreb’s cycle
11. Which lipids are NOT charged at
physiologic pH
a. glycerophospholipids
b. cholesteryl esters
c. sphingomyelins
d. fatty acids
Phosphate (PO4-)
Phosphate (PO4-)
Acid (COOH/COO-)
12. Which molecule is NOT derived from
cholesterol?
a. vitamin D
b. cortisol
c. leukotriene A4
d. taurocholate
Eicosanoid
Stuff made from cholesterol
1. Vitamin D
2. Bile acids
3. Steroids
Adrenocorticoids: Glucocorticoids, mineralocorticoids
Sex hormones: estrogens, testosterone, progesterone
13. Which condition accelerates the
mobilization of fat from adipocytes?
a. activation of lipoprotein lipase
b. activation of phospholipase A2
c. activation of hormone-sensitive lipase
d. activation of acetyl-CoA carboxylase
lipoprotein lipase:
cleaves lipoproteins (VLDL, chylomicrons)
releases triglycerides for tissues
phospholipase A2:
cleaves phospholipids (and sphinogmyelins)
releases fatty acids for eicosanoid synthesis
hormone-sensitive lipase:
cleaves stored fats (adipocytes)
releases fatty acids for gluconeogenesis
acetyl-CoA carboxylase:
converts acetyl-CoA to malonyl-CoA for fatty acid
synthesis
14. Which fatty acid process / cell location is a
correct match?
a. fatty acid activation / cytosol
b. fatty acid oxidation / endoplasmic
reticulum
c. fatty acid desaturation / nucleus
d. fatty acid synthesis / mitochondria
Mitochondria
ER
Cytosol
15. Which condition stimulates the highest rate
in the synthesis of ketone bodies?
a. feasting
b. physical activity
c. overnight sleep
d. starvation
Some get made during normal fasting
Glucose stores are consumed
More fats get consumed for energy
Excess incomplete lipid metabolism
results in ketone body production
16. Which of the following foods contain no
cholesterol?
a. roast beef
b. bacon
c. ice cream
d. baked potato
Not an animal product
17. What disease is caused by a genetic defect
in the enzyme sphingomyelinase leading to
the accumulation of sphingomyelin in the
brain, liver, and spleen?
a. Niemann-Pick disease
b. sudden infant death syndrome (SIDS)
c. Tay-Sachs disease
d. maple syrup urine disease

Niemann-Pick disease:
 Deficiency of sphingomyelinase


Tay-Sach’s disease:
 Defect of hexoseaminidase  build up of
gangliosides


Signs: enlarged liver and spleen, MR, fatal early in life
Signs: MR, blindness, muscular weakness
Maple syrup urine disease:
 Defect in metabolism of branch-chain amino
acids

Signs: take a wild guess
18. Which of the following is an example of an
omega-3 polyunsaturated fatty acid?
a. eicosapentaenoic acid, 20:5 (Δ5,8,11,14,17)
b. arachidonic acid, 20:4 (Δ5,8,11,14)
c. linoleic acid, 18:2 (Δ9,12)
d. docosahexanoic acid, 22:4 (Δ7,10,13,16)
19. In the transportation of fatty acids into the
mitochondria, fatty acyl-CoA needs a carrier
to cross the inner membrane of the
mitochondria. What is the name of this
carrier?
a. creatine
b. lipoate
c. acetyl-CoA
d. carnitine
20. What is the name of the enzyme present in
the capillaries of muscle and adipose tissue
that is activated by apolipoprotein CII to
hydrolyze triacylglycerols to fatty acids and
glycerol?
a. pancreatic lipase
b. lipoprotein lipase
c. hormone sensitive lipase
d. lingual lipase
21. Which is the best source of oleic acid?
a. corn oil
b. olive oil
c. safflower oil
d. soybean oil
Exceptions: plant oils with little PUFA
Coconut oil
High in medium-chain fatty acids
C10-C14
Olive oil
High in oleic acid, a C18 MUFA
C18:1,9
22. Which of the following dietary lipids has
the most influence on raising total blood
cholesterol levels?
Only in conjunction with high kcal
a. cholesterol
b. saturated fatty acids
c. polyunsaturated fatty acids
LOWER blood
d. monounsaturated fatty acids cholesterol levels
23. Which is the preferred polyunsaturated
fatty acid source for the production of the
series 3 prostaglandins?
a. borage oil
b. corn oil
c. linseed oil
d. salmon oil
Omega 6  synthesize
series 1 PGs
ALA  EPA  series 3 PGs… but “sluggish”
C20:3;8,11,14 (DGLA)
ω-6
PG1
LT3
1
3
C20:4;5,8,11,14 (AA)
PG2
LT4
PGI2
TX2
2
4
2
2
PG3
LT5
PGI3
TX3
3
5
3
3
ω-6
C20:5,5,8,11,14,17 (EPA)
ω-3
24. A high omega-6:omega 1 fatty acid ratio in
the diet favors the synthesis of which
eicosanoid via the Δ5-desaturase enzyme
a. 1-series prostaglandins
b. 2-series prostaglandins
c. 3-series prostaglandins
d. 5-series leukotrienes
Associated with normal ω-6 levels
via arachidonic acid..see last slide
Associated with ω-3 pathways
Associated with ω-3 pathways
25. Hydrogenation of polyunsaturated fatty
acids produces which of the following
products that are particularly artherogenic?
a. α-linolenic acids
b. cis-fatty acids
c. gamma-linolenic acids
d. trans-fatty acids
 Trans
versus cis format
 Sources of trans-fatty acids
—Partially hydrogenated margarine,
shortening, commercial frying fat,
high-fat baked goods, salty snacks
26. Triglycerides consist of three fatty acids
attached to a backbone made of which of the
following?
a. glyceraldehyde
b. glycerol
c. sphingosine
d. glycogen
27. Triglycerides contain more energy per gram
than carbohydrates because of what reason?
a. they are denser
b. they are in a more oxidized form
c. they are in a more reduced form
d. they are more hydrophobic
Energy is released by oxidative processes:
β-oxidation, oxidative phosphorylation, glycolysis, Kreb’s
28. Which of the following is a lipid that
functions as a chemical messenger at or near
the site of its production and is directly
derived from arachidonic acid?
a. steroid hormone
b. prostaglandin
c. peptide hormone
d. second messenger
From cholesterol… act far away
Not lipids
May be lipids, but not AA
29. Each round of beta oxidation of fatty acids
produces one molecule each of which of the
following?
a. FADH2, NADH, and acetyl-CoA
b. FADH2, NADPH, and acetyl-CoA
c. FAD, NAD+, and acetyl-CoA
d. FAD, NADP+, and acetyl-CoA
Acyl-CoA + CoASH + FAD + NAD + H2O
Acetyl-CoA + Acyl-CoA + FADH2 + NADH
The FADH2 + NADH are further oxidized in the
electron transport chain for ATP formation
Note:
If EVEN # of carbons in fatty acid
If ODD # of carbons in fatty acid
Acetyl-CoA
Propionyl-CoA
30. The reaction catalyzed by which enzyme
(the target of statin drugs) is the ratelimiting step in cholesterol synthesis?
a. desmolase
b. hydroxymethylglutaryl-CoA reductase
c. squalene epoxidase
d. cyclase
Key Regulatory Enzyme: HMG-CoA reductase
Decreased activity
1. Fasting
2. Cholesterol
3. Dietary cholesterol
4. Statin (analog drugs of mevalonate)
5. Glucagon and glucocorticoids
Increased activity
1. Insulin and Thyroid hormone
1. Which of the following amino acids can be
used to produce pyruvate?
a. isoleucine
b. arginine
c. methionine
d. serine
2. Which of the following amino acids is the
precursor to dopamine?
a. tyrosine
b. phenylalanine
c. lysine
d. tryptophan
Catechol
Catecholamine No longer an
amino acid
3. The amino acid alanine can give rise to what
compound by transamination?
a. phosphoenolpyruvate Glycolysis / gluconeogenesis
b. pyruvate
c. oxaloacetate
Kreb’s cycle
intermediates
d. fumarate
Fate of pyruvate
Glucose
Pyruvate in liver
Post-glycolysis
Pre-Kreb’s
Acetyl-CoA
L-alanine
Lactate
4. Which of the following amino acids is the
one normally found in globular proteins?
a. glutamine
b. serine
c. tyrosine
d. valine
amine
hydroxyl
hydroxyl
Polar vs. Non-polar:
Non-polar side chains
usually get buried in the
interior of protein
Globular proteins are
largely non-polar
5. Which is true of 2,3-bisphosphoglycerate
(BPG)?
a. it is formed from an intermediate
of the pentose phosphate pathway
b. its concentration is four times that of
hemoglobin
c. it weakly attaches to hemoglobin F
d. it is not present in the fetus
glycolysis
equimolar
BPG binds deoxyhemoglobin and stabilizes it
6. Which is true of the O2-saturation curve of
hemoglobin A?
a. it is displaced toward the right
in the presence of an increased
hydrogen ion (H+) concentration
b. it is not influenced by 2,3bisphosphoglycerate (BPG)
c. it is a simple hyperbolic curve
d. it is influenced by nitrogen (N2)
T-form is favored:
thus shifting curve
Always influenced
sigmodal
Huh?
B. Hemoglobin –continued


4 subunits held by non-covalent bonds  4° structure
2° and 3° structures are also flexible… therefore

a variety of factors affect the conformation of Hb
 LOW: pCO2, [H+], [Cl-], [2,3-bisphosphoglycerate]
 HIGH: pO2



Opposite
R-form binds O2, T-form cannot
Cooperative Allosterism: Binding of first O2 takes the longest
time… the rest get progressively faster. This is because
binding O2 changes conformation of other subunits,
facilitating further O2 binding
7. Which amino acid is utilized in the synthesis
of serotonin?
a. histidine
b. phenylalanine
c. tryptophan
d. tyrosine
Histidine  histamine
Phenylalanine  tyrosine  catecholamines
dopamine
norepinephrine
epinephrine
Tryptophan  serotonin
8. Purines are oxidized to the liver to yield
which product?
a. acetic acid
b. oxalic acid
c. glutamic acid
d. uric acid
Purines
Hypoxanthine
Xanthine
Uric acid
Gout
E1: G6Pase
(von Gierke’s)
E2: PRPP
Synthetase
E8: DNase
E6: RNase
E4:
Ribonucleotide
reductase
E5: HGPTase
(Lesch-Nyhan)
E7: Xanthine
Oxidase
(hypouricemia)
E4
9. Legumes are an incomplete source of
protein because they lack which essential
amino acid?
a. lysine
b. methionine
c. threonine
d. tryptophan
Soybean
Nuts
Peanut
Other
Legume
-
+
-
+
-
+
-
Blank:
adequate
+
+
-
+ High
-Low
+
Gelatin
Green
leafy
veggies
Sesame
Sunflower
seed
Grain
Cereal
-
Meat
Eggs
Dairy
-
Met
Ile
Leu
Lys
Phe
Thr
Trp
Val
+
+
+
+
+
+
+
-
-
+
EAA
10. alpha helices and beta pleated sheets
represent aspects of what structure in
proteins?
a. primary
b. secondary
c. tertiary
d. quaternary
Peptide bond
Random coil, beta bending too
3D structure related to function: catalytic site
Multiple subunits
11. Which of the following is an exclusively
ketogenic amino acid?
a. valine
b. glycine
c. aspartate
d. lysine
Two purely ketogenic amino acids to
remember:
Leucine and Lysine
12. Which of the following is a peptide
hormone?
a. thyroxine
b. cortisol
c. glutathione
d. glucagon
Amino Acid derivative
Steroid
Tripeptide: antioxidant
13. What are the isoflavones in soy protein called?
a. genisterin, daidzein, and glycitein
Hormones
b. estrogen and testosterone
Cruciferous veggies
c. indoles and isothiocyanates
Enzymes
d. chymotrypsin and trypsin
14. Which of the following is associated with
the presence of edema in kwashiorkor?
a. inadequate intake of water
b. high plasma albumin levels
c. low plasma albumin levels
d. excessive intake of dietary protein
Kwashiorkor: inadequate protein with adequate kcal.
Therefore, decreased protein synthesis (albumin)
Therefore, fluid accumulates in third space (edema, ascites)
 Consequence:

Kwashiorkor: “Disease of the first child”



Protein-Energy Malnutrition (PEM)
Due to chronic protein deficiency
Signs/Sx: Weakness, edema, loss of hair, skin lesions,
diarrhea, fatty liver, recurrent infections (MCC death is
infection).
Marasmus: Total deficiency of all ergogenic
macronutrients (C, P, F)

No edema. Leads to total loss of body mass
15. What is the name of the uncoupler protein
present in brown fat mitochondria?
a. glycogenin
b. thermogenin
c. lipogenin
d. chymotrypsinogen
Brown fat: burned to keep warm (infants and bears!)
Instead of using fat for ATP production, the ETC is uncoupled and the
energy is released as heat
16. Which amino acid is NOT aromatic?
a. tyrosine
b. phenylalanine
c. histidine
d. tryptophan
Ring structure, but double bonds are not
conjugated
These are the only three aromatic amino acids
17. Which of these molecules is the smallest?
a. insulin
b. glucagon
c. glutathione
d. myoglobin
51 amino acid protein
29 amino acid protein
tripeptide
Multiple polypeptide chains: quaternary
18. Which protein is mostly triple-helical and
practically insoluble in water?
a. elastin
b. collagen
c. myoglobin
d. trypsin
Soluble
in water
Collagen




Most abundant protein in the body
Mature tropocollagen composed of 3 α-chain subunits
3 subunits held together by H-bonds
Different tissues have different amino acid compositions


Ex: Type I collagen is two α-1 and one α-2 chain
Glycine is the most abundant amino acid in collagen, with lots of
proline and lysine
1. What condition applies to an enzymecatalyzed reaction when [S]>Km?
a. velocity is half of Vmax
b. velocity is directly proportional to [S]
c. velocity depends on [E] and [S]
d. velocity is near Vmax
2. What is the name of the inactive precursor
of a protein that is regulated by proteolytic
cleavage?
a. phosphatase
b. zymogen
c. apoprotein
d. peptide
Enzyme that cleaves off phosphates
Protein without ‘prosthetic’ group
Any protein with the suffix “ogen” is a precursor that needs to be
activated by proteolytic cleavage
Ex: trypsinogen
3. The enzyme trypsin is classified as which of
the following?
a. oxidoreductase
b. lyase
c. hydrolase
d. ligase
Break bonds with addition of water
IUB Systematic Classification and nomenclature
International Union of Biochemistry (IUB)
Enzymes are classified into 6 classes according to function:
1. Oxidoreductase
Re-dox reactions: A + B=O  A=O + B
2. Transferase
Transfer groups between substrates
3. Hydrolase
Break substrates by addition of water
4. Lyase
Break substrates without water
5. Isomerase
Convert isomers: AB2  B—A—B
6. Ligase
Ligate with new covalent bond: C—C, O, N, S
Synthetase: uses ATP/GTP as energy source
Synthase: uses other energy
4. Individuals with lactose intolerance are
often capable of tolerating small quantities
of lactose found in which of these dairy
products?
a. buttermilk
b. ice cream
c. milk
d. yogurt
Made with bacteria, which use lactose for
energy
5. In a catalyst reaction by an enzyme, the
maximum initial velocity Vmax is which of
the following?
a. it is achieved when the enzyme is
saturated by a substrate
b. it is equal to two times the MichaelisMenton constant Km
c. it is diminished in the presence of a
competitive inhibitor
d. it is dependent on the concentration of
enzyme utilized
6. Enzymes that utilize coenzymes that are
reversibly oxidized and reduced are in what
class of enzymes?
a. oxidoreductases
b. transferases
c. hydrolases
d. isomerases
Coenzymes like:
NADH/NAD
FAD/FADH2
Also, think “dehydrogenase”
1. Which of the following atoms is added to
the structure of T3 and T4?
a. selenium
b. copper
c. iodine
d. magnesium
T3: tri-iodo-throxine
T4: tetra-iodo-thyroxine
2. Which of these enzymes causes release of
arachidonic acid from membrane
phospholipids?
a. phospholipase A2
b. phospholipase A1
c. phospholipase C
d. phospholipase D
The only phospholipase we care about
These guys cleave phospholipids at
various locations, releasing different
parts
3. Which hormone is derived from an amino
acid
a. insulin
b. epinephrine
c. retinoic acid
d. calcitriol
Peptide hormone: many amino acids
Catecholamine: Phenylalanine  Tyr
Vitamer of vitamin A
Vitamer of vitamin D
4. Which is NOT a normal response to insulin?
a. increased glycolysis
b. increased fatty acid synthesis
c. decreased glycogen degradation
d. decreased glucose uptake
 Insulin


opposes Glucagon/Epinephrine
Increases entry of glucose and neutral amino acids into
target cells
Increases protein synthesis in skeletal muscle
Increases glycolysis (activates glucokinase, PFK-1)
 Decrease gluconeogenesis (inactivates PEPCK gene)





Increases glycogenesis (activates glycogen synthase)
Decreases glycogenolysis (inactivates glycogen
phosphorylase)
Increases lipogenesis (activates acetyl-CoA carboxylase)
Decreases lipolysis (inactivates hormone-sensitive lipase)
5. Which of the following is true of Grave's
disease?
a. it promotes a hypothyroid state in the
affected person
b. it is provoked by the presence of antibody,
which inhibits the TSH receptor
c. it is characterized by a weak
concentration of serum TSH
d. it is characterized by destruction of the
thyroid glands
 IgG
antibody stimulates the thyroid
 Activates the TSH receptor
 Diffuse hypertrophy of the thyroid gland
 Uncontrollable production of T3 and T4
 In
response, the body decreases TSH
6. Which is true of triiodothyronine (T3)?
a. it is a peptide hormone
b. it is recognized by a membrane
receptor on a target cell
c. it is elevated in the serum in goiter
caused by deiodase deficiency
d. at high blood concentrations,
it inhibits protein synthesis
and produces negative
nitrogen balance
thyroglobulin
Nuclear membrane
Deiodase converts T4
to T3
Excessive protein
synthesis = positive
nitrogen balance
7. Leptin, which functions to decrease
appetite, is synthesized in which tissue?
a. liver
b. adipose tissue
c. muscle
d. hypothalamus
Orexigenic: Peptides that INCREASE appetite
Released by






Agouti-related peptide
Neuropeptide Y
Melanin Concentrating Hormone (MCH)
Orexins (hypocretins)
Insulin
Ghrelin
Brain
Brain
Brain
Brain
Pancreas
Stomach
Anorexigenic: Peptides that DECREASE appetite
Released by





Peptide YY: blocks ghrelin
Glucagon-like peptide: delays stomach
emptying, acts on satiety center in brain
Cholecystokinin
Melanocortin: binding R inhibits intake
Leptin: regulates intake of kcal, C, F,
but not percentages of each
Does not prevent obesity
Intestine
Intestine
Intestine
Brain
Adipocyte
8. Glucagon and epinephrine activate adenylyl
cyclase present in the adipocyte cell
membrane that initiates the intracellular
second messenger cascade, which activates
which enzyme?
a. hormone sensitive lipase
b. lipoprotein lipase
Two clues:
c. pancreatic lipase
1. Adipocyte
2. Glucagon/epinephrine
d. lingual lipase
9. The main function of iodine is for the
synthesis of which type of hormone?
a. catecholamine
b. glucocorticoid
c. parathyroid
d. thyroid
Biologically active
form of vitamin D
10. Which hormone stimulates calcitriol
synthesis in the kidneys?
a. aldosterone
b. calcitonin
c. parathyroid hormone
d. thyroxine
PTH and calcitonin
have opposite
effects on Vitamin D
synthesis/activation
11. Which of the following hormones will
stimulate gluconeogenesis?
a. insulin
b. glucagon
c. aldosterone
d. vasopressin
Adrenal hormones:
Cortisol  glucocorticoids  gluconeogenesis
Aldosterone  mineralocorticoids
Vasopressin = ADH
12. Hormones can be members of all of the
following classes of molecules EXCEPT for
which one?
a. peptides
b. lipids
c. carbohydrates
d. amino acid derivatives
1. Which is the final degradation product of
the purine nucleotides in humans?
a. beta alanine
b. xanthine
c. urea
d. uric acid
Catabolism by Nucleases:
Too much uric acid
results in GOUT
Purine Nucleotides 
NH4+ , ribose 1-P, Pi
and uric acid
Pyrimidine Nucleotides
NH4+ , ribose 1-P, Pi,
and CO2, acetate,
β- ALANINE
-aminoisobutyrate
E1: G6Pase
(von Gierk’s)
E2: PRPP
Synthetase
E8: DNase
E6: RNase
E5: HGPTase
(Lesch-Nyhan)
E9
E7: Xanthine
Oxidase
(hypouricemia)
E9: Adenosine
Deaminase
(SCID)
E4
2. Which is a structural difference between
DNA and RNA?
a. DNA contains thymine instead of uracil
b. DNA contains ribose instead of deoxyribose
c. DNA contains uracil instead of thymine
d. DNA contains guanine instead of cytosine
3. Which is the ring structure in pyrimidine
biosynthesis that is placed onto the ribose
phosphate using PRPP?
a. uracil
b. orotate
c. cytosine
d. thymine
E1:Carbamoyl
Phosphate
Synthetase
E2: Aspartate
Transcarbamoylase
E3: PRPP
Synthetase
Inhibited
by CTP
Stimulated by PRPP
Inhibited by UTP
Inhibited by all
mono and diphosphate nts
4. Which of the following is a high-energy
intermediate utilized in the salvage of a free
nitrogenous base to elevate it to the
monophosphate nucleotide level?
a. 5'-phosphoribosylamine
b. 5'-phosphoribosyl-1'-pyrophosphate
c. methenyl-tetrahydrofolate
d. formyl-tetrahydrofolate
PRPP
PPi
Hypoxanthine  Inosine Monophosphate  AMP/GMP
PRPP:
5-phosphoribosyl-1pyrophosphate
5. Activated ribose (PRPP) is a key
intermediate for the synthesis of nucleotides
and some amino acids. Which reaction
represents the activation of ribose?
a. ribose-1-phosphate + ATP  PRPP + AMP
b. ribose-2-phosphate + ATP  PRPP + AMP
c. ribose-3-phosphate + ATP  PRPP + AMP
d. ribose-5-phosphate + ATP  PRPP + AMP
6. Which base is missing in DNA?
a. adenine
b. guanine
c. uracil
d. thymine
7. Among the choices below, which one does
not play a role in the replication of a
bacterial chromosome?
a. UTP (uridine 5'-triphosphate)
Replicates RNA virus genomes
b. reverse transcriptase
c. DNA polymerase I
d. helicases
8. Regarding E. coli, the proofreading of DNA is
performed by what enzyme?
a. 3'-5' exonuclease activity of RNA
polymerase
b. 5'-3' polymerase activity of DNA
polymerases I and III
c. 3'-5' exonuclease activity of DNA
polymerases I, II and III
d. 5'-3' exonuclease activity of DNA
polymerase III
9. Which sugar is involved in the synthesis of
nucleic acids?
a. mannose
b. galactose
c. ribose
d. xylose
… and 2’-deoxyribose for DNA
10. The synthesis of this nucleotide is derived
from vitamin B2
a. DNA
b. FAD
c. NAD
d. RNA
Vitamin B2
Vitamin B3
11. What is the name of the linkage (bond)
that forms the covalent backbone of DNA and
RNA?
a. ester linkage
b. phosphodiester linkage
c. hydrogen bond
d. glycosidic bond
5’-phosphate
2’-deoxyribose
phosphodiester bond:
connects monomers together
H
3’-hydroxyl
12. What is the name of the disease that is
caused by an elevated concentration of uric
acid in the blood and tissues that causes
joints to become inflamed, painful and
arthritic?
Borrelia burgdorferi: fever, headache
a. Lyme disease
b. gout
c. Parkinson's disease Lack of dopaminergic cells, tremors
d. rheumatoid arthritis Not due to uric acid
1. A deficiency in which vitamin is associated
with bleeding gums?
a. vitamin A
b. vitamin B6
c. vitamin C
d. vitamin D
Gingival hemorrhage
bowed legs, stunted bone
growth, and swollen joints.
Infants fed only cow's milk are at
risk of developing scurvy, since
cow's milk is not an adequate
source
of vitamin C.
periungual
hemorrhage
Typical rash
2. What vitamin is not an antioxidant?
a. vitamin A
b. vitamin C
c. vitamin E
d. vitamin K
Antioxidants to know:
1. Vitamin E
2. Vitamin C
3. Vitamin A
4. Selenium
5. glutathione
3. Which of the following iron-containing foods
contains the most absorbable form of dietary
iron?
a. red meat
b. pasta
c. milk
d. spinach
 Factors

Physiologic needs





increasing absorption
Pregnancy, lactation
Growth
Phlebotomy
Menstruation, chronic bleeding
Iron form (e.g. heme, Fe3+)



Ascorbic acid (vitamin C) and low pH enhance absorption by
favoring Fe2+ over Fe3+
Iron supplements in chelated form (ferrous gluconate, etc)
are better than inorganic FeSO4
Best absorbed as heme, as found in hemoglobin and
myoglobin
4. What is the RDA for vitamin C?
a. 60 mg/day
b. 120 mg/day
c. 500 mg/day
d. 1200 mg/day
Not exactly true
 AI
for newborns: 40 mg/day
 RDA


75 mg/day for females
90 mg/day for males
 UL

for adults:
for adults: 2 g/day
A daily intake of 200-300 mg would saturate the blood
(1.2-1.5 mg/dL)

Excess excreted in urine
5. Which of the following is a disease marked
by accumulation of copper in the liver, brain,
kidneys and eye?
a. Menke's disease
b. hemochromatosis
c. goiter
d. Wilson's disease
Copper deficiency
Iron excess
Excess or deficency of
iodine
6. What is the recommended daily intake for
sodium?
a. 1000 mg/day
b. 2400 mg/day
c. 5000 mg/day
d. 10,000 mg/day
Not exactly true
 AI

Adults: 3.8 grams of table salt (1 tsp)


1.5 g of Na
2.3 g Cl
 UL:
5.8 grams of table salt
 Regularly consume salt in excess of UL


More than 90% of American and Canadian men
More than 75% of American and 50% of Canadian
women
7. The dietary precursor in mammals of
coenzyme A is which of the following?
a. pyridoxine
b. niacin
c. biotin
d. pantothenic acid
Anti-pernicious anemia factor
Vitamin B1
FMN
Vitamin B2
Pyridoxamine
Riboflavin
Nicotinic acid
TPP
CoASH
Methylcobalamin
Biotin
Anti-pellagra factor
Thiamin
Vitamin
Form
Biologically
Active
Form
(BAF)
Vitamin B3
Vitamin B5
Vitamin B6
Vitamin B7
Vitamin B9
Vitamin B12
Vitamin C
Pantothenic acid
Vitamin B1
H4-folate
Vitamin B2
Niacinamide
Dehydroascorbic acid
5’-deoxyadenosylcobalamin
Vitamin
Form
FAD
NADP
Anti-beriberi factor
Pantetheine
Folacin
Pyridoxal phosphate
Biologically
Active
Form
(BAF)
Vitamin B3
Vitamin B5
Vitamin B6
Vitamin B7
Vitamin B9
Vitamin B12
Vitamin C
8. Which is true of thiamine (vitamin B1)
a. it is a lipid soluble vitamin
b. it is necessary in humans because a deficiency
can cause pellagra
c. it is a coenzyme that participates in oxidative
decarboxylation of alpha-keto acids
d. it is made up of two nitrogen bases, two
sugars and two phosphates
ADEK
B3
FAD
9. Tetrahydrofolate is a coenzyme that permits
the transfer of what substances?
a. amine groups
b. CO2 (or bicarbonate)
c. monocarbon groups other than CO2
d. multicarbon groups
Folate and tetrahydroflate are for
METHYL transfer
10. Which vitamin is NOT required for the
function of the pyruvate dehydrogenase
complex?
a. thiamine
Note: This complex may
b. niacin
simply be called
“pyruvate dehydrogenase”
c. pyridoxine
d. pantothenic acid
Pyruvate  Acetyl CoA
Keys to remember:
Coenzymes are required for this sequential and coupled rxn
Thiamine (vitamin B1)Thiamine PyroPhosphate
i. TPP
ii. Lipoate
Cofactor for many aerobic reactions 
justifies it as a dietary supplement
iii. CoASH
Obviously … Gets oxidized (derivative of Vit B5)
iv. FAD
derived from riboflavin (vitamin B2) required for
electron transfer
v. NAD+
Nicotinamide adenine dinucleotide, derived from
niacin (vitamin B3)
11. Niacin deficiency is associated with which
disease?
a. rickets
b. pellagra
c. xeropthalmia
d. scurvy
Vitamin D
Vitamin A
Vitamin C
Don’t forget the 3 Ds:
Dementia, diarrhea, dermatitis
12. The RDA for what mineral in women of
child-bearing age is more than double the
RDA for men?
a. calcium
b. magnesium
c. zinc
d. iron
Newborn
0.27 mg/day
Adult
males
8 mg/day
Adult
females 19-50
18 mg/day
Adult
females 51+
8 mg/day
Pregnancy
27 mg/day
13. Phylloquinones and menaquinones are
natural forms of which vitamin?
a. vitamin A
b. vitamin D
c. vitamin E
d. vitamin K
cholecalciferol
14. In what organ does the
enzymes alpha-1-hydroxylase
hydroxylate vitamin D3
(cholecalciferol) to its fully
active hormonal form?
a. liver
b. kidney
c. pancreas
d. intestines
hydroxylation
25-hydroxy-cholecalciferol
hydroxylation
1,25-dihydroxy-cholecalciferol
15. Which of the following foods is a good
source of provitamin A carotenoids?
a. pears
b. roast beef
c. cantaloupe
d. cauliflower
Think yellow or orange
16. Which vitamin / mineral pair is essential
for glycolysis?
a. riboflavin / calcium
b. niacin / magnesium
c. niacin / calcium
d. riboflavin / magnesium
Know your vitamins:
B2 – FAD
B3 - NAD
Rule of thumb:
Whenever ATP is
involved think Mg2+
17. The pyruvate dehydrogenase complex
catalyzes the conversion of pyruvate to
acetyl-CoA in mitochondria. Which vitamin is
NOT needed for this reaction?
a. thiamine
b. pantothenate
c. pyridoxine
d. riboflavin
Know your vitamins!
B1, B2, B3 and B5 are required
18. Which condition / vitamin deficiency is
NOT a correct match?
a. night blindness / vitamin A
b. hemolysis / vitamin D
Hemolysis / vitamin E
c. hemorrhage / vitamin K Rickets (osteomalcia) / vitamin D
d. pellagra / niacin
1. What makes enzymes effective catalysts?
a. they increase the energy released during a
reaction
b. they increase the activation energy
required for a reaction
c. the decrease the equilibrium of the
reaction
d. they decrease the activation energy
required for a reaction
TRANSITION STATE
2. What type of reversible inhibitor competes
with the substrate for the active site of the
enzyme?
a. noncompetitive inhibitor
b. competitive inhibitor
c. uncompetitive inhibitor
d. mixed inhibitor
Competes for active site
All other inhibitors bind to sites other than the active site
3. For this reaction, AB, the ΔG’˚= 5.7
kJ/mol at 25˚C. Which is the correct
equilibrium?
a. [B] = [A]
b. Keq = 100
c. [B] > [A]
d. 10[B] = [A]
Not enough information was given,
therefore impossible to know.
(However, I seriuosly doubt this will
be asked on Boards)
4. Which is a characteristic of a near-equilibrium
cellular reaction?
a. Keq and Q differ by several orders of magnitude
b. ΔG is large and negative
c. the reaction is potentially a regulatory point
d. the reaction is reversible
Keq: equilibrium constant at standard (in vitro) conditions
Q: equilibrium constant at steady-state (in vivo) conditions
Regulatory points: tightly regulated therefore nowhere near
Large negative ΔG: spontaneous and fast
5. A cereal breakfast bar containing 3g fat, 2 g
protein, and 30g of carbohydrates has
approximately how many calories?
a. 140
b. 150
c. 155
d. 290
Atwater
Carbs:
Protein:
Fat:
coefficients:
4 kcal/g
4 kcal/g
9 kcal/g
(3x9) + (2x4) + (30x4) =
27 + 8 + 120 =
155
6. Which vitamin-derived nucleotide is NOT
involved in energy production within the
Kreb's cycle or electron transport chain?
a. NADPH
b. FMN
c. FAD
d. NAD
Fatty acid, cholesterol and DNA synthesis
7. Biochemical reactions are considered to be
reversible if their ΔG'˚ is which of the
following?
a. large and positive
b. large and negative
c. close to zero
d. equal to delta H˚'
8. A biochemical reaction taking place in a
healthy human with a large positive ΔG can
proceed in the forward direction only if
which of the following is TRUE?
a. it is catalyzed by an enzyme
b. it is coupled with a reaction with a
larger negative ΔG
c. the temperature is increased
d. the activation energy is lowered
A little bit of a trick question:
(what’s missing)
9. The functional electron transport systems can
be formed in vitro from purified components of
the respiratory chain and vascular membranes.
Assuming the presence of O2, succinate,
ubiquinone (UQ), cytochrome c, and complexes
III and IV, the final electron acceptor is which of
the following?
a. succinate
b. complex III
c. complex IV
d. H2O
According to the question, it could pass to complex IV
Not an electron acceptor
Complex I
Complex III
Complex IV
Complex II
10. Which of the following is TRUE of the
Kreb's cycle?
a. it is implicated in the synthesis of glucose
from acetyl-CoA
b. it can function equally well aerobically
and anaerobically
c. it requires pyridoxal phosphate and lipoic
acid for its activity
d. it is inhibited by an elevated
intracellular level of ATP, NADH and
citrate
ENZYME
ACTIVATOR
INHIBITOR
Citrate Synthase
High NAD/NADH High ATP/ ADP
Isocitrate
Dehydrogenase
High ADP/ATP
High ATP/ ADP
high NADH/NAD
α-ketoglutarate
dehydrogenase
CoASH, pyruvate,
high ADP/ATP
Fatty acids, ketone
bodies
High NADH/NAD
Oxaloacetate
Succinate thiokinase Mg2+
/dehydrogenase
11. The passage of a high-energy phosphate
from one organic structure to another and
facilitated by an enzyme is given what term?
a. oxidative phosphorylation
b. oxidase phosphorylation
c. redox phosphorylation
d. substrate-level phosphorylation
Enzyme
Reaction catalyzed Pathway
Molecule
generated
Phosphoglycerate
kinase
1,3-BPG to 3PG
Glycolysis
ATP
Pyruvate kinase
PEP to pyruvate
Glycolysis
ATP
Succinyl-CoA
synthetase
Succinyl-CoA to
succinate
Kreb’s cycle
GTP
ATP synthase
ADP to ATP
ETC
ATP
Creatine
(phospho)kinase
Phosphocreatine to
creatine
Skeletal muscle ATP
and brain
12. The majority of the energy conserved in
the TCA cycle is by the harvesting of which of
the following?
a. high-energy phosphates
b. high-energy esters
c. high-energy thioesters
d. high-energy electrons
…as NADH and FADH2