Biochemistry Problem Sets, 3rd ed.

practice problems to Sison Review Center’s lectures on Biochemistry

Table of Contents

PS B-01. Foundations of Biochemistry, Amino Acids, and Proteins ....................................................... 2

PS B-02. Enzymes.................................................................................................................................. 4
PS B-03. Carbohydrates......................................................................................................................... 6
PS B-04. Lipids and Biological Membranes ........................................................................................... 8
PS B-05. Nucleic Acids......................................................................................................................... 10
PS B-06. Information Pathways ........................................................................................................... 12
PS B-07. Bioenergetics and Oxidative Phosphorylation ....................................................................... 14
PS B-08. Carbohydrate Metabolism..................................................................................................... 16
PS B-09. Lipid Metabolism .................................................................................................................. 18
PS B-10. Nitrogen Metabolism ............................................................................................................ 20
PS B-B. Check Point B .......................................................................................................................... 22
SISON REVIEW CENTER: Chemistry Boards Review
Biochemistry: PS B-01. Foundations of Biochemistry, Amino Acids, and Proteins

PS B-01. Foundations of Biochemistry, Amino Acids, and Proteins

General Instructions: Answer the following multiple-choice questions and shade in your answer on the provided answer
sheet. Consult your instructor for the deadline of submission.

1. Which group of single-celled microorganisms 6. What is the pI of the following amino acid?
has many members found growing in extreme
environments? HO2C (CH2)n NH2
A) Bacteria
B) Archaea NH2
C) Eukaryotes
D) Heterotrophs
E) None of the above pKa1= 2.2 pKa2= 9.0 pKa3= 10.5
+
-CO2H -NH3 R group
2. Hydrophobic interactions make important
energetic contributions to: A) 1.5
A) binding of a hormone to its receptor protein. B) 6.3
B) enzyme-substrate interactions. C) 5.6
C) membrane structure. D) 9.8
D) three-dimensional folding of a polypeptide E) 6.8
chain.
E) All of the above are true. 7. Which of these natural amino acids contains a
heterocyclic ring?
3. Which two amino acids differ from each other A) Asparagine
by only one atom? B) Proline
A) Ser and Thr C) Arginine
B) Leu and Ile D) Histidine
C) Ala and Ser E) Two of these
D) Asp and Asn
E) Ser and Cys 8. The binding of oxygen to hemoglobin is said to
be _______________.
4. For amino acids with neutral R groups, at any A) high affinity
pH below the pI of the amino acid, the B) low affinity
population of amino acids in solution will have: C) sigmoidal
A) a net negative charge. D) cooperative
B) a net positive charge. E) sequential
C) no charged groups.
D) no net charge. 9. Which of the following reversible reactions of
E) positive and negative charges in equal carbon dioxide explains how hemoglobin serves
concentration. as a transporter of carbon dioxide?
A) reaction with the imidazole group of the
5. At the isoelectric pH of a tetrapeptide: distal histidine where oxygen would
A) only the amino and carboxyl termini normally be bound
contribute charge. B) reaction with the carboxyl group of glutamic
B) the amino and carboxyl termini are not acid to form a carbonic acid anhydride
charged. C) reaction with the N-terminal amino groups
C) the total net charge is zero. to form a carbamate
D) there are four ionic charges. D) reaction with the hydroxyl group of serine to
E) two internal amino acids of the tetrapeptide form a carbonate
cannot have ionizable R groups. E) none of the above

PS B-01. Foundations of Biochemistry, Amino Acids, and Proteins | Page 2 of 27

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Biochemistry: PS B-01. Foundations of Biochemistry, Amino Acids, and Proteins

10. ____ are examples of antiparallel -helix 13. What structure(s) did Pauling and Corey predict
proteins. in 1951?
A) Triose phosphate isomerase A) α helix
B) Pyruvate kinase B) β sheet
C) Flavodoxin C) β turns
D) Hemoglobin D) a, b, and c
E) Papain E) a and b

11. Collagen has the following characteristics 14. An ELISA can be used for
EXCEPT: A) quantitative analysis.
A) Tropocollagen is the basic structural unit. B) size analysis
B) There is about 33% glycine in collagen. C) protein sequencing
C) Both intermolecular and intramolecular D) All of the above.
crosslinks help to stabilize the collagen E) None of the above.
fibrils.
D) Modification of prolines occurs prior to 15. What is the Bohr effect?
collagen synthesis. A) the ability of hemoglobin to retain oxygen
E) Inextendable fibrous protein are when in competition with myoglobin
components of connective tissues. B) the regulation of hemoglobin-binding by
hydrogen ions and carbon dioxide
12. In the majority of -helixes, each peptide C) the alteration of hemoglobin conformation
carbonyl is hydrogen bonded to the peptide during low oxygen stress
N−H group ____ residues farther ____ the D) All of the above.
chain. E) None of the above.
A) 2, down
B) 4, up
C) 3, down
D) 2, up
E) 4, down

PS B-01. Foundations of Biochemistry, Amino Acids, and Proteins | Page 3 of 27

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Biochemistry: PS B-02. Enzymes

PS B-02. Enzymes
General Instructions: Answer the following multiple-choice questions and shade in your answer on the provided answer
sheet. Consult your instructor for the deadline of submission.

1. What type(s) of inhibition can be reversed? 7. All of the following are properties of a coenzyme
A) competitive EXCEPT:
B) noncompetitive A) They are usually actively involved in the
C) mixed
D) All of the above.
catalytic reaction of the enzyme.
B) They tend to be stable to heat. pr
E) None of the above. C) They can serve as intermediate carriers of
functional groups. V
2. In this type of inhibition, the inhibitor can only D) They are protein components.
bind to the ES complex to form an ESI complex E) They may contain vitamins as part of their
A) competitive structure. ~
B) noncompetitive
C) mixed 8. The catalytically active complex of an
D) uncompetitive apoenzyme and its prosthetic group is referred
E) None of the above. to a(n) ____ .
A) catalytic duo
3. Which of the following is an example of a B) holoenzyme
zymogen? C) prosthetic enzyme
A) pepsinogen D) dimeric enzyme
B) procarboxypeptidase E) none of the above
C) T-form of ACTase
D) All of the above. 9. If an enzyme has a Vmax of 15 mM/min, what is
E) a and b the velocity if the substrate is present at 1/5 of
the Km? at km : VojVmax=

Vmax [S]
4. Examples of covalent modification include A) 12 mM/min Vi =

+1 +
[ S 3 km

A) phosphorylation and dephosphorylation. B) 6 mM/min Vi = Vmax [S]

B) acetylation C) 3 mM/min vi Vmax

=
km

C) ubiqutination D) 2.5 mM/min 15

D) All of the above. E) cannot be determined from given
E) All of the above. information

5. Allosteric proteins 10. All are true for kcat EXCEPT :

A) usually display hyperbolic Michaelis-Menten A) referred to as the molecular activity of the
kinetics. enzyme. V
B) often display cooperativity. B) called the turnover number of the enzyme. ~
C) always consist of several identical subunits. C) measures the maximal catalytic activity or
D) a and b kinetic efficiency of an enzyme. V
E) a, b, and c D) defines the number of substrate molecules
converted into product/enzyme
6. If the rate constant for the enzyme catalyzed molecule/unit of time when the enzyme is
reaction is 2 x 105/sec and the rate constant saturated with substrate. V
for the uncatalyzed reaction is 2 x 10−6/sec, the E) all are true.
catalytic power of the enzyme is:
A) 1011 11. Proinsulin is converted into insulin by:
B) 2 x 10−11 A) proteolytic excision of a specific peptide.
C) 10-11 B) allosteric binding of glucose.
D) 10-1 C) phosphorylation to the active form.
E) 2 x 10-1 D) removal of phosphate by converter
enzymes.
E) none of the above.

PS B-02. Enzymes | Page 4 of 27

SISON REVIEW CENTER: Chemistry Boards Review
Biochemistry: PS B-02. Enzymes

12. Which one of the following statements is true of 14. In a plot of l/V against 1/[S] for an enzyme-
enzyme catalysts? catalyzed reaction, the presence of a
A) They bind to substrates but are never competitive inhibitor will alter the:
covalently attached to substrate or product. A) curvature of the plot.
B) They increase the equilibrium constant for a B) intercept on the l/[S] axis.
reaction, thus favoring product formation. C) intercept on the l/V axis.
C) They increase the stability of the product of D) pK of the plot.
a desired reaction by allowing ionizations, E) Vmax.
resonance, and isomerizations not normally
available to substrates. 15. In the mechanism of chymotrypsin, which of the
D) They lower the activation energy for the following amino acids found in the active site is
conversion of substrate to product. correctly defined in terms of its role in the
E) To be effective, they must be present at the reaction?
same concentration as their substrates. A) serine: hydrogen bonds with carbonyl
oxygen to withdraw electron density from
13. Which of the following statements about a plot the substrate
of V0 vs. [S] for an enzyme that follows B) histidine: deprotonates aspartic acid to
MichaelisMenten kinetics is false? allow a nucleophilic attack to occur
A) As [S] increases, the initial velocity of C) aspartic acid: electrostatic stabilization of
reaction V0 also increases. ~ histidine to make a stronger base
B) At very high [S], the velocity curve becomes D) cysteine: performs a nucleophilic attack on
a horizontal line that intersects the y-axis at the carbonyl carbon of the substrate
Km. E) none of the above
C) Km is the [S] at which V0 = 1/2 Vmax. W
D) The shape of the curve is a hyperbola. V
E) The y-axis is a rate term with units of
µm/min. V

PS B-02. Enzymes | Page 5 of 27

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Biochemistry: PS B-03. Carbohydrates

PS B-03. Carbohydrates
General Instructions: Answer the following multiple-choice questions and shade in your answer on the provided answer
sheet. Consult your instructor for the deadline of submission.

1. An aldaric acid is represented by: 3. Which reagent will distinguish between the
members of the following pair?

CHO CO2H
H OH H OH
HO H HO H
H OH H OH
H OH H OH
CH2OH CH2OH

I II
A) Ag(NH3)2+
B) AgNO3/C2H5OH
C) Br2/CCl4
D) HCl
E) Hot KMnO4
A) I
B) II 4. An aldopentose, X, is subjected to a Kiliani-
C) III Fischer synthesis to produce two aldohexoses,
D) IV Y and Z. Both Y and Z, when oxidized with nitric
E) V acid, yield optically active aldaric acids. Which
structure represents X?
2. Which of the following is a D-aldotetrose?
A) I
B) II
C) III
D) IV
E) V

5. Cellulose differs from chitin in which way?

A) Cellulose has -glycosidic linkages; chitin
has -glycosidic linkages.
B) Cellulose contains only D-glucose units;
chitin contains only N-acetyl-D-glucosamine
units.
A) I
C) Cellulose cannot be hydrolyzed; chitin can
B) II be hydrolyzed.
C) III
D) Cellulose has a linear structure; chitin has a
D) IV helical structure.
E) V E) Cellulose chains are branched; chitin chains
are unbranched.

PS B-03. Carbohydrates | Page 6 of 27

SISON REVIEW CENTER: Chemistry Boards Review
Biochemistry: PS B-03. Carbohydrates

6. What are lectins? 11. Gluconic acid is derived from ________ while
A) Proteins that bind the carbohydrates on glucuronic acid is derived from _______.
glycoproteins and other macromolecules A) glucose; gulose
B) Proteins that promote cell cell interaction B) gulose; glucose
C) Proteins found in animals, plants, and C) glucose; glucose
microorganisms D) glucose; galactose
D) All of the above E) galactose; glucose
E) None of the above
12. Which of the following is not a reducing sugar?
7. Sugar alcohols include all of the following A) Fructose
EXCEPT: B) Glucose
A) ribitol. C) Glyceraldehyde
B) sorbitol. D) Ribose
C) fucose. E) Sucrose
D) mannitol.
E) glycerol. 13. D-Glucose is called a reducing sugar because it
undergoes an oxidation-reduction reaction at
8. All are true for cellulose and -amylose EXCEPT: the anomeric carbon. One of the products of
A) Both are linear homopolymers of glucose. this reaction is:
B) Both have (1→4) linkages. A) D-galactose.
C) Both form extended ribbon most stable B) D-gluconate.
conformations. C) D-glucuronate.
D) Both have extensive intramolecular D) D-ribose.
hydrogen bonding. E) muramic acid.
E) All are true.
14. Which of the following statements about starch
9. Which of the following best describes the and glycogen is false?
glycosidic bond below? A) Amylose is unbranched; amylopectin and
glycogen contain many ( 1 → 6)
branches.
B) Both are homopolymers of glucose.
C) Both serve primarily as structural elements
in cell walls.
D) Both starch and glycogen are stored
intracellularly as insoluble granules.
A) (2→4) E) Glycogen is more extensively branched than
B) (1→3) starch.
C) (1→4)
D) (1→3) 15. Which of the following techniques is not
E) (2→4) commonly used to study oligosaccharide
structures?
10. An N-linked glycan would be attached to ______ A) X-ray crystallography
while an O-linked glycan would be attached to B) Matrix-assisted laser desorption/ionization
________. mass spectroscopy (MALDI-MS)
A) Asn; Ser C) Nuclear magnetic resonance (NMR)
B) Lys; Tyr D) Complete chemical synthesis
C) Gln; Thr E) Oligosaccharide microarrays
D) Arg; Ser
E) Lys; Ser

PS B-03. Carbohydrates | Page 7 of 27

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Biochemistry: PS B-04. Enzymes

PS B-04. Lipids and Biological Membranes

General Instructions: Answer the following multiple-choice questions and shade in your answer on the provided answer
sheet. Consult your instructor for the deadline of submission.

1. Which of these lipids does not yield glycerol 5. How many isoprene units are in vitamin A?
upon hydrolysis? OH

A) A lecithin A) 1
B) A sphingolipid B) 2
C) A cephalin C) 3
D) A triacylglycerol D) 4
E) A plasmalogen E) More than 4

2. 6. Which of the following characteristics are found

OCH2CH2N(CH3)3 is a structural unit of in the class of C20 carboxylic acids called
which type of phosphatide? prostaglandins?
A) Cephalins A) a five membered ring
B) One or more double bonds
B) Phosphatidyl serines
C) Plasmalogens C) Several oxygen containing groups
D) Two of the above
D) Lecithins
E) Both C) and D) E) All of the above

7. Carbohydrate residues attached to the

3. Which is not a correct statement concerning
membrane lipids are almost always
naturally-occurring triacylglycerols?
A) The greater the degree of unsaturation, the A) positioned on the intracellular side of the
membrane.
higher the melting point.
B) Saponification yields glycerol and a mixture B) positioned on the inside center of the
of carboxylic acid salts. bilayer.
C) Solid examples are termed "fats." C) positioned on the extracellular side of the
D) Regardless of the exact nature of the R membrane
D) positioned equally on both sides of the
groups, such compounds are water-
membrane.
insoluble.
E) also covalently attached to membrane
E) Such compounds frequently, but less
correctly, are called "triglycerides." proteins.

8. A channel that opens in response to binding a

4. Which compound is a sesquiterpene?
particular molecule is called a ________
OH
channel.
A) passive diffusion
I II B) symport
C) ligand-gated
D) ABC-protein
E) None of the above

9. Aquaporins are found in high levels in all of the

following tissues except
III IV V A) the kidneys.
A) I B) salivary glands.
B) II
C) the cornea.
C) III
D) red blood cells.
D) IV
E) the liver.
E) V

PS B-04. Enzymes | Page 8 of 27

SISON REVIEW CENTER: Chemistry Boards Review
Biochemistry: PS B-04. Enzymes

10. The movement of potassium ions across a 13. Tay-Sachs disease is the result of a genetic
membrane aided by valinomycin is an example defect in the metabolism of:
of _ A) gangliosides.
A) facilitated diffusion by transport through a B) phosphatidyl ethanolamine.
pore C) sterols.
B) facilitated diffusion by transport using a D) triacylglycerols.
carrier molecule E) vitamin D.
C) facilitated diffusion by use of a permease
D) primary active transport since valinomycin is 14. Identify the molecule(s) derived from sterols.
a sodium-potassium ATPase A) Arachidonic acid
E) secondary active transport since B) Gangliosides
valinomycin only moves with the aid of the C) Phosphatidylglycerol
sodium ion gradient D) Prostaglandins
E) Cortisol
11. What alcohol containing a quaternary amine is
commonly found esterified to 15. Which of the following techniques is not
glycerophospholipids? commonly used to analyze lipid composition?
A) ethanolamine A) Selective extraction using apolar solvents
B) choline B) Adsorption chromatography
C) serine C) X-ray crystallography
D) inositol D) Hydrolysis using enzymes with specificity
E) cholesterol for certain linkages
E) Mass spectroscopy
12. Biological waxes are all:
A) triesters of glycerol and palmitic acid.
B) esters of single fatty acids with long-chain
alcohols.
C) triesters of glycerol and three long chain
saturated fatty acids.
D) sphingolipids.
E) None of the above

PS B-04. Enzymes | Page 9 of 27

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Biochemistry: PS B-05. Nucleic Acids

PS B-05. Nucleic Acids

General Instructions: Answer the following multiple-choice questions and shade in your answer on the provided answer
sheet. Consult your instructor for the deadline of submission.

1. Which is the predominant tautomeric form of 4. The analytical data for DNA samples which led
cytosine when it is present in DNA? to generalizations such as (%G + %A)  (%C +
NH2 NH NH %T) came from the research of what individual?
H
N N N A) James Watson
B) Francis Crick
N O N O N O C) Edwin Chargaff
D) Arthur Kornberg
I II III E) Maurice Wilkins
A) I
B) II 5. Which is an incorrect statement concerning the
C) III DNA double helix?
D) None of these A) The sugar-phosphate backbone is on the
E) I, II and III are present in approximately outside of the helix and the base pairs are
equal amounts. on the inside. V
B) The two strands are identical but proceed in
2. The following structure represents the less opposite directions.
common (in DNA, at least) tautomeric form of C) Hydrogen bonding holds together the two
__________. strands. V
OH D) Only purine-pyrimidine base pairs can be
accommodated. V
H3C E) The sugar-phosphate backbone is
N completely regular. V

N O 6. The phosphodiester bonds that link adjacent

nucleotides in both RNA and DNA:
A) always link A with T and G with C.
A) Cytosine B) are susceptible to alkaline hydrolysis.
B) Thymine C) are uncharged at neutral pH.
C) Adenine D) form between the planar rings of adjacent
D) Guanine bases.
E) Uracil E) join the 3' hydroxyl of one nucleotide to the
5' hydroxyl of the next.
3. If the base sequence along a segment of DNA
were G—C—C—A—T, what would be the base 7. Based on Chargaff's rules, which of the
sequence of messenger RNA synthesized from following are possible base compositions for
this sequence? double-stranded DNA?
A) G—C—C—A—T
B) C—G—G—T—A %A %G %C %T %U
C) C—G—G—U—A A) 5 45 45 5 0
D) G—C—C—A—U B) 20 20 20 20 20
E) A—T—T—G—C C) 35 15 35 15 0
D) All of the above
E) None of the above

PS B-05. Nucleic Acids | Page 10 of 27

SISON REVIEW CENTER: Chemistry Boards Review
Biochemistry: PS B-05. Nucleic Acids

8. B-form DNA in vivo is a ________-handed helix, 13. Inosine, one of the common alternative bases
_____ Å in diameter, with a rise of ____ Å per found in RNA, is shown below. How would
base pair. inosine form hydrogen bonds in a double helical
A) left; 20; 3.9 section of RNA?
B) right; 18; 3.4
C) right; 18; 3.6
D) right; 20; 3.4
E) right; 23; 2.6

9. When double-stranded DNA is heated at neutral

pH, which change does not occur?
A) The absorption of ultraviolet (260 nm) light
increases.
B) The covalent N-glycosidic bond between the
base and the pentose breaks.
C) The helical structure unwinds. ~ A) 1 H-bond donor group, 0 H-bond acceptor
D) The hydrogen bonds between A and T break. V groups
E) The viscosity of the solution decreases. V B) 0 H-bond donor groups, 1 H-bond acceptor
group
10. In nucleotides and nucleic acids, syn and anti C) 1 H-bond donor group, 1 H-bond acceptor
conformations relate to: group
A) base stereoisomers. D) 2 H-bond donor groups, 1 H-bond acceptor
B) rotation around the phosphodiester bond. group
C) rotation around the sugar-base bond. E) 1 H-bond donor group, 2 H-bond acceptor
D) sugar pucker. groups
E) sugar stereoisomers.
14. Which of the following secondary structures is
11. The net charge on nucleotide monophosphates correctly identified?
is: A) Z-DNA: left-handed DNA with pyrimidines in
A) +1 the syn conformation and purines in the anti
B) 0 conformation
C) -1 B) hairpin structure: self-complimentary single
D) -2 stranded molecules that form a parallel
E) -3 helix
C) cruciform: a double hairpin formed in a
12. 30S rRNA is a designation of the ____ of the region of palindromic DNA
RNA molecule. D) H-DNA: triple helical structure that results
A) number of sugars when Watson-Crick base pairing does not
B) sedimentation coefficient form and instead, Hoogsteen base pairing
C) splicing coefficient occurs
D) sequence repeats E) none of the above
E) splicing number
15. The experiment of Avery, MacLeod, and McCarty
in which nonvirulent bacteria were made
virulent by transformation was significant
because it showed that:
A) bacteria can undergo transformation.
B) genes are composed of DNA only.
C) mice are more susceptible to pneumonia
than are humans.
D) pneumonia can be cured by transformation.
E) virulence is determine genetically.

PS B-05. Nucleic Acids | Page 11 of 27

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Biochemistry: PS B-06. Information Pathways

PS B-06. Information Pathways

General Instructions: Answer the following multiple-choice questions and shade in your answer on the provided answer
sheet. Consult your instructor for the deadline of submission.

1. Reverse transcriptase is normally encoded in 6. What reaction is carried out by -galactosidase?

DNA from A) Lactose is hydrolyzed to galactose and
A) plants. sucrose.
B) retroviruses. B) Lactose is hydrolyzed to galactose and
C) mitochondria. glucose.
D) All of the above. C) Lactose is hydrolyzed to two molecules of
E) None of the above. glucose.
D) Lactose is hydrolyzed to two molecules of
2. Actinomycin interferes with transcription by galactose.
A) binding to the RNA polymerase. E) None of the above.
B) binding the DNA-RNA duplex.
C) binding to the DNA helix and preventing its 7. Histone binding and wrapping of DNA reduces
use as an RNA template. the DNA length by
D) binding to σ subunits A) 2-fold
E) None of the above. B) 7-fold
C) 20-fold
3. Huntington disease is caused by D) 100-fold
A) pyrimidine dimers. E) 1000-fold
B) trinucleotide expansion
C) suppressor mutants. 8. How does the lac repressor inhibit
D) All of the above. transcription?
E) Noneof the above. A) It binds to the RNA polymerase and
prevents its association to the DNA.
4. Aflatoxin B1 is a compound that is converted to B) It binds to the DNA and prevents the RNA
a reactive epoxide by cytochrome P450 and polymerase from unwinding and
causes transcribing the DNA.
A) a G-C to T-A transversion C) It binds to the mRNA molecule, preventing
B) an intrastrand cross-link ribosomes from binding.
C) deamination of adenine D) All of the above.
D) All of the above. E) None of the above.
E) Noneof the above.
9. Individual amino acids are attached to their
5. A disease caused by mutations in pre-mRNA or corresponding tRNAs:
in the splicing factors includes A) through an ester linkage to the 3'-OH in the
A) Birketts lymphoma. acceptor stem.
B) Thalassemia B) through an amide linkage to the anticodon
C) Retinitis pigmentosa. loop.
D) Sickle cell anemia C) through an amide linkage to the adenine
E) None of the above ring at the 3'end of the tRNA.
D) through a phosphoester linkage to the 5'
end of the tRNA.
E) None of the above.

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SISON REVIEW CENTER: Chemistry Boards Review
Biochemistry: PS B-06. Information Pathways

10. DNA intercalating agents include all of the 13. In order for lysogeny to occur, the enzyme
following EXCEPT: ______________ must insert the phage DNA
A) ethidium bromide. into a specific site in the bacterial chromosome.
B) actinomycin D. A) ligase
C) acridine orange. B) lysogenase
D) streptomycin. C) helicase
E) all are true. D) integrase
E) none of the above
11. At the transcriptional level, how does
tryptophan control the production of genes 14. Which subunit of E. coli RNA polymerase is
within the trp operon? responsible for the RNA polymerization
A) the trp repressor contains a high reaction?
percentage of Trp residues and is thus only A) 
produced when Trp levels are high B) 
B) without sufficient Trp, the production of the C) 
trp repressor is truncated, thus producing a D) 
protein that cannot bind to the operon, E) 
ultimately resulting in structural gene
expression 15. What is a polyribosome?
C) high levels of Trp cause the repressor to be A) ribosomes that synthesize different
proteolytically digested subunits of the same protein
D) the trp repressor binds to the operon only B) several ribosomes all attached to the same
when bound to Trp mRNA
E) none of the above C) ribosomes that are covalently bonded to
each other in a polymer fashion
12. A pseudogene is a ___________. D) a ribosome that only produces proteins that
A) gene that codes for a non-functional protein will be excreted by the cell
B) nonexpressed gene E) none of the above
C) mutated gene
D) gene with multiple promoter regions that
causes the start of transcription to be
mistaken
E) none of the above

PS B-06. Information Pathways | Page 13 of 27

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Biochemistry: PS B-07. Bioenergetics and Oxidative Phosphorylation

PS B-07. Bioenergetics and Oxidative Phosphorylation

General Instructions: Answer the following multiple-choice questions and shade in your answer on the provided answer
sheet. Consult your instructor for the deadline of submission.

1. The reduced form of flavin adenine dinucleotide 6. The standard free-energy changes for the
is reactions below are given.
A) FADH.
B) FAD. Phosphocreatine  creatine + Pi
C) FADH++. ΔG'° = –43.0 kJ/mol
D) FADH2. ATP  ADP + Pi ΔG'° = –30.5 kJ/mol
E) None of the above.
What is the overall ΔG'° for the following
2. Which of the following is the electron donor reaction?
used for reductive biosynthesis?
A) NADH Phosphocreatine + ADP → creatine + ATP
B) NADPH A) –73.5 kJ/mol
C) FADH2 B) –12.5 kJ/mol
D) CoA C) +12.5 kJ/mol
E) ATP D) +73.5 kJ/mol
E)  G'° cannot be calculated without Keq'.
3. Which activated carriers contain adenosine
phosphate units?
7. E'° of the NAD+/NADH half reaction is –0.32 V.
A) NADH
The E'° of the oxaloacetate/malate half
B) FADH2
reaction is –0.175 V. When the concentrations
C) coenzyme A
of NAD+, NADH, oxaloacetate, and malate are
D) A and B
all 10–5 M, the “spontaneous” reaction is:
E) A, B, and C
A) malate + NAD+ → oxaloacetate + NADH +
4. Which of the following is an example of an H+.
oxidation reaction? B) malate + NADH + H+ → oxaloacetate +
A) - H CO 2
-
NAD+.
C) NAD+ + NADH + H+ → malate +
-
O 2C CH2 CH2 CO 2 + FAD C C + FADH2
-
O 2C H

B) O O oxaloacetate.
-
CH3CCO2 + CO2 + ATP
-
O2CCH2CCO2
-
+ ADP + Pi D) NAD+ + oxaloacetate → NADH + H+ +
C) CO 2
-
CO 2
-
malate.
H2N C H H C NH2
E) oxaloacetate + NADH + H+ → malate +
CH3 CH3
NAD+.
D) Ala-Ser + H2O → Ala + Ser
E) None of the above 8. Reduced QH2 is not formed by which of the
following?
5. For the following reaction, ΔG'° = +29.7 kJ/mol. A) Complex I and NADH
L-Malate + NAD+ → oxaloacetate + NADH + H+ B) Complex II and succinate
The reaction as written: C) Complex III and cytochrome c
A) can never occur in a cell. D) Fatty acid oxidation
B) can occur in a cell only if it is coupled to E) Oxidation of glycerol-3-phosphate
another reaction for which  G'° is positive.
C) can occur only in a cell in which NADH is
converted to NAD+ by electron transport.
D) cannot occur because of its large activation
energy.
E) may occur in cells at some concentrations
of substrate and product.

PS B-07. Bioenergetics and Oxidative Phosphorylation | Page 14 of 27

SISON REVIEW CENTER: Chemistry Boards Review
Biochemistry: PS B-07. Bioenergetics and Oxidative Phosphorylation

9. Mammals produce heat by using the 13. All are flavoproteins EXCEPT:
endogenous uncoupling agent: A) NADH-CoQ reductase (complex I).
A) the small molecule 2-4-Dinitrophenol B) succinate dehydrogenase (complex II).
synthesized by the cell. C) coenzyme Q-cytochrome c oxidoreductase
B) the protein thermogenin. (complex III).
C) the protein thioredoxin. D) sn-glycerolphosphate dehydrogenase.
D) the protein cytochrome c. E) fatty acyl-CoA dehydrogenase-transferring
E) a modified form of the FoF1 ATPase. protein.

10. Upon the addition of 2,4-dinitrophenol (DNP) to 14. Bacteria and other prokaryotic cells have the
a suspension of mitochondria carrying out capacity to get more ATP/glucose oxidized than
oxidative phosphorylation linked to the eukaryotic cells because ____, so they are more
oxidation of malate, all of the following occur efficient.
except: A) they are simpler and have less going on
A) oxygen consumption decreases. B) they don't have to use shuttles to reoxidize
B) oxygen consumption increases. reduced nucleotides
C) the P/O ratio drops from a value of C) they do not have to translocate ATP-ADP
approximately 2.5 to 0. across the mitochondrial membranes
D) the proton gradient dissipates. D) they use an electron transport chain that
E) the rate of transport of electrons from NADH translocates more protons
to O2 becomes maximal. E) none of the above

11. The inhibition by an unknown inhibitor of 15. Does electron transport stop if rotenone is
electron transport was found to be removed by added? Why?
a large concentration of phenazine A) Yes, there is not an electron source.
methosulfate. Since phenazine methosulfate is B) No, rotenone is not strong enough to inhibit
known to accept electrons from cytochrome b all of the electron transport chain.
of complex III, which of the following is most C) No, there is still a source of electrons from
similar to the unknown inhibitor? Complex II.
A) amytal D) Yes, rotenone inhibits complex III, therefore,
B) antimycin A electrons can not be passed on.
C) carbon monoxide E) Can not be determined from the information
D) cyanide given.
E) rotenone

12. __________ increases oxygen consumption

while decreasing ATP synthesis, but
____________ decreases both oxygen
consumption and ATP synthesis.
A) rotenone; valinomycin
B) azide; 2,4-dinitrophenol
C) antimycin A; nigericin
D) 2,4-dinitrophenol; oligomycin
E) cyanide; valinomycin

PS B-07. Bioenergetics and Oxidative Phosphorylation | Page 15 of 27

SISON REVIEW CENTER: Chemistry Boards Review
Biochemistry: PS B-08. Carbohydrate Metabolism

PS B-08. Carbohydrate Metabolism

General Instructions: Answer the following multiple-choice questions and shade in your answer on the provided answer
sheet. Consult your instructor for the deadline of submission.

1. The glyoxylate cycle enables plants to survive 6. An individual with von Gierke's disease lacks
using only the enzyme ____ which is a liver enzyme used
A) pyruvate to maintain ____. As a result, the patient is
B) acetate ____.
C) oxaloacetate A) glycogen synthase; liver glycogen; fat
D) All of the above B) glycogen synthase; ATP levels; weak
E) None of the above. C) phosphoprotein phosphatase-1; blood
glucose; hypoglycemic
2. Which of the following vitamins are precursors D) glucose-6-phosphatase; blood glucose;
to coenzymes that are necessary for the hypoglycemic
formation of acetyl-CoA from pyruvate? E) glucose-6-phosphatase; muscle glycogen;
A) Thiamine, riboflavin, niacin, lipoic acid, and weak
pantothenic acid
B) Thiamine, riboflavin, niacin, lipoic acid, 7. Which of the following enzymes would be
pantothenic acid, and biotin activated by phosphorylation as a result of
C) Thiamine, riboflavin, niacin, and biotin glucagon binding to its receptor on the cell
D) Thiamine, riboflavin, and lipoic acid membrane?
E) None of the above A) pyruvate carboxylase
B) glycogen synthase
3. Glycerol from hydrolysis of triacylglycerols C) pyruvate kinase
enters glycolysis at: D) fructose-2,6-bisphosphatase
A) glyceraldehyde-3-phosphate. E) none of the above
B) 3-phosphoglycerate.
C) 2-phosphoglycerate. 8. All of the following are inhibitors of citrate
D) dihydroxyacetone phosphate. synthase EXCEPT:
E) 1,3-bisphosphoglycerate. A) acetyl-CoA
B) NADH
4. The rare hereditary galactosemia involves C) succinyl-CoA
defects in: D) ATP
A) galactokinase. E) all are inhibitors
B) galactose-1-phosphate uridylyltransferase.
C) phosphoglucomutase. 9. Which of the following molecules is correctly
D) UDP-glucose-4-epimerase. paired with the enzyme that can convert it to
E) UDP-glucose pyrophosphorylase. oxaloacetate to replenish the citric acid cycle
when other intermediates are removed?
5. If yeast cells were given glucose that was A) aspartate: aspartate deaminase
labeled with 14C at carbon 3, where would the B) pyruvate: malic enzyme
14C by found after glycolysis under anaerobic C) phosphoenolpyruvate: PEP carboxylase
conditions? D) glutamate: glutamate transaminase
A) CO2 E) none of the above
B) Ethanol, C1
C) Ethanol, C2
D) Lactic acid, C1
E) Lactic acid, C3

PS B-08. Carbohydrate Metabolism | Page 16 of 27

SISON REVIEW CENTER: Chemistry Boards Review
Biochemistry: PS B-08. Carbohydrate Metabolism

10. The conversion of citrate to isocitrate by the 13. Complete the following reaction for
enzyme aconitase is best described as ______ photosystem I (be sure to balance the reaction
reaction consisting of a ________ followed by a with regard to the electrons):
________. Pc(Cu+) + Fdox + light →
A) isomerization; oxidation; reduction A) Pc(Cu+) + Fdox + light → Pc (Cu+) + (Cu+)
B) isomerization; hydration; dehydration Fdred
C) isomerization; dehydration; hydration B) Pc(Cu+) + Fdox + light → Pc (Cu2+) + Fdred
D) group transfer; dehydroxylation; C) Pc(Cu+) + Fdox + light → Pc + Fdred(Cu2+)
hydroxylation D) Pc(Cu+) + Fdox + light → Pc– (Cu3+) + Fdred
E) group transfer; hydroxylation; E) None of the above
dehydroxylation
14. The C4 pathway is necessary in tropical plants
11. What specific part of the chloroplast is because
responsible for the light reactions of A) at high temperatures, the plants cannot
photosynthesis? maintain sufficient water levels within the
A) thylakoid lumen
cells.
B) thylakoid membrane
B) tropical plants do not have proper day/light
C) stroma cycles to maintain the balance of CO2
D) inner membrane of chloroplast necessary for carbohydrate storage.
E) outer membrane of chloroplast C) at high temperatures, the oxygenase activity
of rubisco is high.
12. Which of the following depicts the general flow D) All of the above.
of electrons in the two-photosystem light E) None of the above
reactions?
(Q = plastoquinone, PC = plastocyanin, Fd =
15. The experimental determination of the
ferredoxin effectiveness of light of different colors in
A) PSI → Q → cytochrome b6f complex → PC promoting photosynthesis is called the:
→ PSII → Fd → NADP+ A) absorption spectrum.
B) PSI → cytochrome b6f complex → Q → PC B) action spectrum.
→ PSII → Fd → NADP+ C) difference spectrum.
C) PSII → Q → cytochrome b6f complex → PC D) reflectance spectrum.
→ PSI → Fd → NADP+ E) refraction spectrum.
D) PSII → PC → Q → Fd → PSI → cytochrome
b6f complex → NADP+
E) PSII → Fd → PC → cytochrome b6f complex
→ PSI → Q → NADP+

PS B-08. Carbohydrate Metabolism | Page 17 of 27

SISON REVIEW CENTER: Chemistry Boards Review
Biochemistry: PS B-09. Lipid Metabolism

PS B-09. Lipid Metabolism

General Instructions: Answer the following multiple-choice questions and shade in your answer on the provided answer
sheet. Consult your instructor for the deadline of submission.

1. The role of lipoprotein particles is to 6. Which of the following is (are) true of the
A) solubilize hydrophobic lipids oxidation of 1 mol of palmitate (a 16-carbon
B) aid in clot formation. saturated fatty acid; 16:0) by the ß-oxidation
C) transport insoluble proteins. pathway, beginning with the free fatty acid in
D) B and C. the cytoplasm?
E) None of the above
1. Activation of the free fatty acid requires the
2. In phosphatidyl inositol, __________ and equivalent of two ATPs.
_________ usually occupy the C-1 position and 2. Inorganic pyrophosphate (PPi) is produced.
the C-2 position, respectively. 3. Carnitine functions as an electron acceptor.
A) stearic acid; cholesterol 4. 8 mol of FADH2 are formed.
B) stearic acid; arachidonic acid 5. 8 mol of acetyl-CoA are formeiopd.
C) palmitolyl acid; arachidonic acid 6. There is no direct involvement of NAD+.
D) oleic acid; arachidonic acid A) 1 and 5 only
E) None of the above B) 1, 2, and 5
C) 1, 3, and 5
3. Respiratory distress syndrome is caused by a D) 1, 3, and 5
failure in the biosynthetic pathway of E) 5 only
A) sphingosine
B) gangliosides 7. The balanced equation for the degradation of
C) dipalmitoyl phosphatidyl choline. CH3(CH2)10COOH via the ß-oxidation pathway is:
D) cholesterol A) CH3(CH2)10COOH + 5FAD + 5NAD+ +
E) bile salts 6CoA—SH + 5H2O + ATP →
6 Acetyl-CoA + 5FADH2 + 5NADH + 5H+ +
4. Free fatty acids in the bloodstream are: AMP + PPi
A) bound to hemoglobin. B) CH3(CH2)10COOH + 5FAD + 5NAD+ +
B) carried by the protein serum albumin. 6CoA—SH + 5H2O →
C) freely soluble in the aqueous phase of the 6 Acetyl-CoA + 5FADH2 + 5NADH + 5H+
blood. C) CH3(CH2)10COOH + 6FAD + 6NAD+ +
D) nonexistent; the blood does not contain free
fatty acids. 6CoA—SH + 6H2O + ATP →
6 Acetyl-CoA + 6FADH2 + 6NADH + 6H+ +
E) present at levels that are independent of
epinephrine. AMP + PPi
D) CH3(CH2)10COOH + 6FAD + 6NAD+ +
5. Fatty acids are activated to acyl-CoAs and the 6CoA—SH + 6H2O
6 Acetyl-CoA + 6FADH2 + 6NADH + 6H+
acyl group is further transferred to carnitine
because:
8. In the disease sprue, vitamin B12 (cobalamin) is
A) acyl-carnitines readily cross the
mitochondrial inner membrane, but acyl- poorly absorbed in the intestine, resulting in B12
CoAs do not. deficiency. If each of the following fatty acids
B) acyl-CoAs easily cross the mitochondrial were in the diet, for which one would the
process of fatty acid oxidation be most affected
membrane, but the fatty acids themselves
will not. in a patient with sprue?
C) carnitine is required to oxidize NAD+ to A) CH3(CH2)10COOH
B) CH3(CH2)11COOH
NADH.
C) CH3(CH2)12COOH
D) fatty acids cannot be oxidized by FAD unless
they are in the acyl-carnitine form. D) CH3(CH2)14COOH
E) None of the above is true. E) CH3(CH2)18COOH

PS B-09. Lipid Metabolism | Page 18 of 27

SISON REVIEW CENTER: Chemistry Boards Review
Biochemistry: PS B-09. Lipid Metabolism

9. If the 16-carbon saturated fatty acid palmitate 12. In the synthesis of phosphatidylcholine from
is oxidized completely to carbon dioxide and phosphatidylethanolamine, the methyl group
water (via the ß-oxidation pathway and the citric donor is:
acid cycle), and all of the energy-conserving A) a tetrahydrofolate derivative.
products are used to drive ATP synthesis in the B) choline.
mitochondrion, the net yield of ATP per C) methanol.
molecule of palmitate is: D) S-adenosylmethionine (adoMet).
A) 3. E) serine.
B) 10.
C) 25. 13. Which of the following is derived from a sterol?
D) 108. A) Bile salts
E) 1000. B) Gangliosides
C) Geraniol
10. Which of the following is not true of the fatty D) Phosphatidylglycerol
acid synthase and the fatty acid ß-oxidation E) Prostaglandins
systems?
A) A derivative of the vitamin pantothenic acid 14. Which of these statements about the regulation
is involved. of cholesterol synthesis is not true?
B) Acyl-CoA derivatives are intermediates. A) Cholesterol acquired in the diet has
C) Double bonds are oxidized or reduced by essentially no effect on the synthesis of
pyridine nucleotide coenzymes. cholesterol in the liver.
D) The processes occur in different cellular B) Failure to regulate cholesterol synthesis
compartments. predisposes humans to atherosclerosis.
E) The processes occur in the mitochondrial C) High intracellular cholesterol stimulates
matrix. formation of cholesteryl esters.
D) Insulin stimulates HMG-CoA reductase.
11. The rate-limiting step in fatty acid synthesis is: E) Some metabolite or derivative of cholesterol
A) condensation of acetyl-CoA and malonyl- inhibits HMG-CoA reductase.
CoA.
B) formation of acetyl-CoA from acetate. 15. Which of these compounds is not synthesized
C) formation of malonyl-CoA from malonate by a pathway that includes isoprene
and coenzyme A. precursors?
D) the reaction catalyzed by acetyl-CoA A) Natural rubber
carboxylase. B) Plastoquinone
E) the reduction of the acetoacetyl group to a C) Vitamin A
ß-hydroxybutyryl group. D) Vitamin B12
E) Vitamin K

PS B-09. Lipid Metabolism | Page 19 of 27

SISON REVIEW CENTER: Chemistry Boards Review
Biochemistry: PS B-10. Nitrogen Metabolism

PS B-10. Nitrogen Metabolism

General Instructions: Answer the following multiple-choice questions and shade in your answer on the provided answer
sheet. Consult your instructor for the deadline of submission.

1. In the urea cycle, free NH3 is coupled with 7. Under which circumstances are amino acids not
carboxyphosphate to form metabolized via oxidative degradation?
A) ureatic phosphate. A) Starvation
B) pyruvate B) Plants growing in nutrient-rich soils
C) carbamic acid C) Normal protein turnover
D) urea D) A diet rich in proteins
E) None of the above E) Uncontrolled diabetes

2. Ketogenic amino acids are degraded to which 8. Which of the following statements about the
of the following metabolites? fixation of atmospheric nitrogen (N2) into NH3
A) Pyruvate by living cells is false?
B) Acetyl-CoA A) It involves the transfer of eight electrons per
C) Acetoacetate mol of N2.
D) All of the above B) It occurs in certain microorganisms, but not
E) B and C in humans. V
C) It requires a source of electrons, normally
3. Which amino acid(s) is (are) solely ketogenic? ferredoxin V
A) Leucine D) It requires one ATP per mol of N2 fixed.
B) Tryptophan E) It requires two key protein components,
C) Lysine each containing iron. v
D) A and B
E) A and C 9. Glutamine synthetase converts _____ to _____
whereas glutamate synthase converts ____ to
4. Chorismate is a precursor to the amino acids _____.
A) tryptophan, tyrosine, and phenylalanine. A) formate; glutamine; ammonia; glutamate
B) tryptophan and phenylalanine. B) asparagine; glutamine; -ketoglutarate;
C) tyrosine and phenylalanine. glutamate
D) tryptophan, tyrosine, phenylalanine, and C) -ketoglutarate; glutamine; oxaloacetic
serine. acid; glutamate
E) all of the above. D) -ketoglutarate; glutamine; -
ketoglutarate; glutamate
5. This amino acid is added to indole to in the E) glutamate; glutamine; -ketoglutarate;
biosynthesis of tryptophan: glutamate
A) glutamine
B) serine 10. Nonessential amino acids:
C) tyrosine A) are amino acids other than those required
D) all of the above. for protein synthesis.
E) none of the above. B) are not utilized in mammalian proteins.
C) are synthesized by plants and bacteria, but
6. Which amino acids supply carbons for eventual not by humans.
entry into metabolism as succinyl CoA? D) can be synthesized in humans as well as in
A) Met, Val, Leu bacteria.
B) Met, Ile, Val E) may be substituted with other amino acids
C) Ile, Val, Leu in proteins.
D) All of the above
E) None of the above

PS B-10. Nitrogen Metabolism | Page 20 of 27

SISON REVIEW CENTER: Chemistry Boards Review
Biochemistry: PS B-10. Nitrogen Metabolism

11. Erythrose 4-phosphate is a precursor of: 14. The hormones epinephrine and norepinephrine
A) aspartate. are derived biosynthetically from:
B) cysteine. A) arginine.
C) phenylalanine. B) histidine.
D) serine. C) isoleucine.
E) threonine. D) tryptophan.
E) tyrosine.
12. Homoserine is:
A) a precursor of both methionine and 15. Glutathione is a(n):
threonine. A) enzyme essential in the synthesis of
B) a precursor of serine. glutamate.
C) derived from homocysteine. B) isomer of oxidized glutamic acid.
D) derived from serine. C) methyl-group donor in many biosynthetic
E) derived from threonine. pathways.
D) product of glutamate and methionine.
13. The plant hormone indole-3-acetate (auxin) is E) tripeptide of glycine, glutamate, and
formed from: cysteine.
A) arginine.
B) histidine.
C) phenylalanine.
D) threonine.
E) tryptophan.

PS B-10. Nitrogen Metabolism | Page 21 of 27

SISON REVIEW CENTER: Chemistry Boards Review
Biochemistry: PS B-B. Check Point B

PS B-B. Check Point B

General Instructions: Answer the following multiple-choice questions and shade in your answer on the provided answer
sheet. Consult your instructor for the exact deadline.

1. Which of the following is correctly paired? 5. When glucagon binds to receptors on

A) adenine: pyrimidine mammalian liver cells, which of the following
B) RNA: ribose containing nucleic acid occurs due to enzyme phosphorylation?
C) thymine: purine A) activation of PFK-2 followed by activation of
D) uracil: purine glycolysis
E) DNA: ribose containing nucleic acid B) activation of FBPase-2 followed by inhibition
of gluconeogenesis
2. One of the enzymes involved in glycolysis, C) activation of PFK-2 followed by activation of
aldolase, requires Zn2+ for catalysis. Under gluconeogenesis
conditions of zinc deficiency, when the enzyme D) activation of FBPase-2 followed by
may lack zinc, it would be referred to as the: activation of gluconeogenesis
A) apoenzyme. E) activation of PFK-2 followed by inhibition of
B) coenzyme. glycolysis
C) holoenzyme.
D) prosthetic group. 6. Partial hydrogenation accomplishes which of
E) substrate. the following?
A) prevents oxidative cleavage of carbon-
3. Of the following amino acids, which will have a carbon double bonds, thus preventing
pI closest to 3? spoilage of fats
A) Cys B) raises the melting point of fatty acids
B) His C) converts cis double bonds to trans double
C) Gly bonds
D) Asp D) converts oils into fats
E) Lys E) all of the above

4. A flippase is an enzyme that moves lipids from 7. Which of the following is not a
one side of a lipid bilayer to another in order to glycerophospholipid?
maintain the concentrations of specific lipids on A) Phosphatidylcholine
each side of the bilayer. Which of the following B) Phosphatidylethanolamine
can be said regarding the reaction of the C) Phosphatidylserine
flippase enzyme? D) Cardiolipin
A) it works against a concentration gradient E) Ceramide
and requires ATP
B) it works against a concentration gradient
but does not require ATP
C) it works with a concentration gradient and
requires ATP
D) it works with a concentration gradient but
does not require ATP
E) none of the above

PS B-B. Check Point B | Page 22 of 27

SISON REVIEW CENTER: Chemistry Boards Review
Biochemistry: PS B-B. Check Point B

8. Compound X is a reducing sugar which, on 12. What sequence of enzymes allows for the
hydrolysis, affords two molar equivalents of D- synthesis of glycogen from glucose-6-
glucose. This hydrolysis is catalyzed by an phosphate?
enzyme specific for glucosides of this type: A) UDP-glucose pyrophosphorylase,
phosphoglucomutase, glycogen synthase,
CH2OH amylo-(1,4→1,6)-transglycosylase
O B) phosphoglucomutase, UDP-glucose
pyrophosphorylase, amylo-(1,4→1,6)-
OH transglycosylase, glycogen synthase
OH OR C) phosphoglucomutase, amylo-(1,4→1,6)-
OH transglycosylase, UDP-glucose
pyrophosphorylase, glycogen synthase
What is the identity of X? D) UDP-glucose pyrophosphorylase,
A) Sucrose phosphoglucomutase, amylo-(1,4→1,6)-
B) Lactose transglycosylase, glycogen synthase
C) Maltose E) phosphoglucomutase, UDP-glucose
D) Cellobiose pyrophosphorylase, glycogen synthase,
E) None of these amylo-(1,4→1,6)-transglycosylase

9. A G protein is inactive when the _____ subunit 13. Which subunit of E. coli RNA polymerase is
is bound to __________. responsible for DNA binding?
A) ; GMP A) 
B) ; GDP B) 
C) ; GMP C) 
D) ; GDP D) 
E) /; GMP E) 

10. For each molecule of CO2 fixed by the Calvin 14. Which of the following is a product of xanthine
cycle, how many ATP and NADPH are required? dehydrogenase?
A) 3 ATP, 1 NADPH A) hypoxanthine
B) 3 ATP, 2 NADPH B) uric acid
C) 6 ATP, 2 NADPH C) guanine
D) 6 ATP, 3 NADPH D) xanthosine
E) none of the above E) allantoin

11. Lactose, the disaccharide of galactose and 15. When oxygen is bound to myoglobin, the amino
glucose, is synthesized from which of the acid _____ is complexed to the iron ion of the
following activated monosaccharides? heme group while _______ forms a hydrogen
A) uridine triphosphate glucose bound to the oxygen.
B) uridine triphosphate galactose A) cysteine; serine
C) uridine diphosphate glucose B) cysteine; histidine
D) uridine diphosphate galactose C) serine; cysteine
E) none of the above D) histidine; histidine
E) histidine; cysteine

PS B-B. Check Point B | Page 23 of 27

SISON REVIEW CENTER: Chemistry Boards Review
Biochemistry: PS B-B. Check Point B

16. Threonine is converted into acetyl-CoA and 18. Which of the following is an inhibitor of citrate
pyruvate while proline is converted into - synthase, isocitrate dehydrogenase, and -
ketoglutarate. Classify each of these amino ketoglutarate dehydrogenase?
acids. A) NADH
A) threonine is ketogenic, proline is ketogenic B) succinyl-CoA
B) threonine is ketogenic and glucogenic, C) ATP
proline is ketogenic D) acetyl-CoA
C) threonine is ketogenic, proline is glucogenic E) none of the above
D) threonine is ketogenic and glucogenic,
proline is glucogenic 19. Which of the following is used to drive glucose
E) none of the above uptake by intestinal epithelial cells?
A) potassium gradient across the blood
17. Which of the following would be the correct vessel/epithelial cell membrane
Haworth projection for -D-gulose, whose linear B) potassium gradient across the intestinal
form is seen below? lumen/epithelial cell membrane
C) sodium gradient across the blood
vessel/epithelial cell membrane
D) sodium gradient across the intestinal
lumen/epithelial cell membrane
E) none of the above

20. Which of the following best describes the

cholesterol molecule?
A) Amphipathic
B) Nonpolar, charged
A) C) Nonpolar, uncharged
D) Polar, charged
E) Polar, uncharged

21. What is the minimum number of photons that

must be absorbed by PSII to reduce two
molecules of water to one molecule of oxygen?
B) A) 1
B) 2
C) 4
D) 8
E) 16

22. Each cycle in PCR includes

C) A) DNA synthesis.
B) hybridization of primers.
C) strand separation.
D) b and c only
E) a, b and c above.

23. The primary activation of triacylglycerol

mobilization in adipocytes is through
D) __________ of the enzyme ____________.
A) phosphorylation; perilipin
B) phosphorylation; hormone sensitive lipase
C) dephosphorylation; hormone sensitive
lipase
D) phosphorylation; adipose triglyceride lipase
E) dephosphorylation; adipose triglyceride
E) none of the above lipase

PS B-B. Check Point B | Page 24 of 27

SISON REVIEW CENTER: Chemistry Boards Review
Biochemistry: PS B-B. Check Point B

24. Which are paired by a Shine-Dalgarno 29. The conversion of ribulose-5-phosphate to

sequence? xylulose-5-phosphate requires what enzyme?
A) the mRNA sequence just upstream from the A) phosphopentose isomerase
start codon with the ribosome B) phosphopentose epimerase
B) the first codon of the mRNA with its tRNA C) transketolase
C) a termination codon with a release factor D) transaldolase
D) the 30S subunit with the 50S subunit of the E) lactonase
ribosome
E) none of the above 30. Which amino acid utilizes nitrogen and carbon
from adenine in the synthesis of its R-group?
25. Which of the following hormones binds to a A) histidine
receptor tyrosine kinase? B) arginine
A) thyroxine C) lysine
B) epinephrine D) asparagine
C) epidermal growth factor E) all of the above
D) glucagon
E) cortisol 31. Which technique cannot be used for
quantitative analysis?
26. In addition to iron, what metal is found in A) x-ray crystallography
certain cytochromes? B) ELISA
A) manganese C) absorbance spectroscopy
B) copper D) All of the above.
C) chromium E) None of the above.
D) cobalt
E) zinc 32. How is specificity determined by chymotrypsin?
A) interaction of the active site amino acids
27. The first three reactions of -oxidation are with the substrate
analogous to which of the following reaction B) binding of the N-terminus amino acid at the
sequences of the citric acid cycle? active site
A) aconitase, isocitrate dehydrogenase, - C) covalent binding of a his residue to the
ketoglutarate dehydrogenase substrate
B) isocitrate dehydrogenase, -ketoglutarate D) large conformational change of a P-loop
dehydrogenase, succinyl-CoA synthetase upon binding of substrate
C) -ketoglutarate dehydrogenase, succinyl- E) binding of the proper amino acid into a deep
CoA synthetase, succinate dehydrogenase pocket on the enzyme
D) succinate dehydrogenase, fumarase,
malate dehydrogenase 33. The conversion of 3-phosphoglycerate to
E) fumarase, malate dehydrogenase, citrate phosphoenolpyruvate requires two reactions.
synthase Which of the following correctly identifies the
types of reactions in the proper order of
28. Which of the following could contribute to glycolysis?
quaternary structure? A) isomerization, hydration
A) charge-charge interaction between arginine B) hydration, isomerization
and glutamic acid C) dehydration, isomerization
B) disulfide bond D) isomerization, dehydration
C) hydrogen bond between threonine hydroxyl E) mutation, dehydration
group and imidazole ring of histidine
D) hydrophobic interaction between
phenylalanine and tryptophan
E) all of the above

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SISON REVIEW CENTER: Chemistry Boards Review
Biochemistry: PS B-B. Check Point B

34. Which of the following types of DNA are often 39. The reaction of ammonia with -ketoglutarate is
supercoiled? catalyzed by _________ and requires _________
A) extremely long linear DNA, such as seen in as a reactant.
human chromosomes A) glutamate synthetase; ATP
B) very short linear DNA B) glutamate synthetase; NADH or NADPH
C) circular DNA C) glutamate dehydrogenase; ATP
D) DNA molecules that contain both circular D) glutamate dehydrogenase; NADH or NADPH
and linear regions E) none of the above
E) all of the above
40. Which of the following is a diastereomer of D-
35. Vmax for an enzyme-catalyzed reaction: mannose?
A) generally increases when pH increases. A) D-gulose
B) increases in the presence of a competitive B) D-altrose
inhibitor. C) D-idose
C) is limited only by the amount of substrate D) D-talose
supplied. E) all of the above
D) is twice the rate observed when the
concentration of substrate is equal to the 41. Which of the following lists the enzymes (in
Km. order) required to transport a molecule of
E) is unchanged in the presence of a acetyl-CoA from the mitochondrion to the
uncompetitive inhibitor. cytosol while returning the “acetyl-CoA
acceptor” back to the mitochondrion?
36. Which of the following amino acids is derived A) citrate synthase, citrate lyase, pyruvate
from another amino acid by the addition of an carboxylase
amine group? B) citrate synthase, citrate lyase, malate
A) lysine dehydrogenase, pyruvate carboxylase
B) asparagine C) citrate synthase, citrate lyase, malate
C) arginine dehydrogenase, pyruvate carboxylase, malic
D) histidine enzyme
E) none of the above D) citrate synthase, citrate lyase, malate
dehydrogenase
37. In the Klenow fragment of many DNA E) citrate synthase, citrate lyase, malate
polymerases, the Mg2+ ions that are required dehydrogenase, malic enzyme
for activity are coordinated to which amino acid
R-groups? 42. What is the standard-state free energy (ΔG°′)
A) histidine and aspartate for the hydrolysis of ATP to ADP?
B) two aspartates A) +45.6 kJ/mol
C) aspartate and asparagine B) −45.6 kJ/mol
D) aspartate and glutamate C) − kJ/mol
E) glutamate and glutamine D) −15.6 kJ/mol
E) + kJ/mol
38. Which of the following photosynthetic pigments
would give rise to the yellow or red color of
leaves seen during autumn?
A) chlorophyll a
B) chlorophyll b
C) -carotene
D) phycocyanin
E) none of the above

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SISON REVIEW CENTER: Chemistry Boards Review
Biochemistry: PS B-B. Check Point B

43. Which one of the following statements is true of 44. How is trypsinogen converted to trypsin?
enzyme catalysts? A) A protein kinase-catalyzed phosphorylation
A) They bind to substrates but are never converts trypsinogen to trypsin.
covalently attached to substrate or product. B) An increase in Ca2+ concentration promotes
B) They increase the equilibrium constant for a the conversion.
reaction, thus favoring product formation. C) Proteolysis of trypsinogen forms trypsin.
C) They increase the stability of the product of D) Trypsinogen dimers bind an allosteric
a desired reaction by allowing ionizations, modulator, cAMP, causing dissociation into
resonance, and isomerizations not normally active trypsin monomers.
available to substrates. E) Two inactive trypsinogen dimers pair to form
D) They lower the activation energy for the an active trypsin tetramer.
conversion of substrate to product.
E) To be effective, they must be present at the 45. To calculate the turnover number of an enzyme,
same concentration as their substrates. you need to know:
A) the enzyme concentration.
B) the initial velocity of the catalyzed reaction
at [S] >> Km.
C) the initial velocity of the catalyzed reaction
at low [S].
D) the Km for the substrate.
E) both A and B.

PS B-B. Check Point B | Page 27 of 27