Questions of biochemistry with answers of all chapter

What are the chemical elements that
form most of living biological matter?
The chemical elements that form most
of the molecules of living beings are
oxygen (O), carbon (C), hydrogen (H)
and nitrogen (N).

• Glucose and fructose are examples of
A. double sugars
B. disaccharides
C. single sugars
D. polysaccharides

• What are described as the "building
blocks of Protein"?
A. Fiber
B. Lipids
C. Amino Acids
D. Nutrients

• (CH2O)n is the molecular formula for
which type of macromolecules?
A. Proteins
B. Lipids
C. Carbohydrates
D. Nucleic Acid

• Which macromolecule does not
dissolve in water?
A. proteins
B. lipids
C. carbohydrates
D. nucleic acids

• What type of organic substances are
fats?
A. nucleic acid
B. carbohydrate
C. protein
D. lipids

• What are the monomers of lipids?
A. Amino acids
B. Simple sugars
C. Fatty acids and glycerol
D. Nucleic acids

• Which of the following is a polymer?
A. nucleic acid
B. fatty acid
C. Amino acid
D. Glycerol

• Proteins are ____ made of amino
acid ____ .
A. monomers; polymers
B. polymers; polypeptides
C. polymers; monomers
D. monomers; molecules

• Which of the following is NOT a
polysaccharide?
A. Glycogen
B. Starch
C. Sucrose
D. Cellulose

• What are used in animals as a source of
quick energy that can be stored in the
liver and muscles ？
A. Proteins
B. Nucleic acids
C. Carbohydrates
D. Lipids

• Fats that have fatty acids with only single
covalent bonds in their carbon skeletons
are
A. saturated
B. unsaturated
C. found in plants instead of animals
D. liquid at room temperature

• Sugars, starches, and cellulose belong
to which major class of biological
molecules?
A. Nucleic acids
B. carbohydrates
C. lipids
D. polypeptides

• Plants like sugar cane and sugar beets store
the energy as simple sugars. Other plants,
like corn and potatoes, store the energy as
more complex sugars called?
A. carbohydrates
B. calories
C. starches
D. cellulose

• This biological macromolecule is
responsible for controlling the activity of the
cell, and it stores and transports genetic
information.
A. Carbohydrate
B. Nucleic acid
C. Water
D. Glucose

• In this type of structure, most of carbonyl
groups of peptide bonds forms a hydrogen
bond with the amide nitrogen of another
peptide bond four amino acids further down
the polypeptide chain:
A. Alpha-helix
B. Beta-sheet
C. Beta-turn
D. Quaternary

• Lipids are used by the body to perform all
of the following functions EXCEPT:
A. membrane structural material.
B. enzyme action.
C. insulation.
D. a rich energy source.

• What is the
constitutional unit of
proteins?
• What is the primary
structure of a
protein?
• The constitutional
units of proteins are
the amino acids.
• The primary protein
structure is the linear
sequence of amino
acids that form the
molecule.

What is the secondary structure of a
protein?
• The secondary protein structure is generated by
the manner its amino acids interact through the
inter-residue bond. These interactions create a
spatial conformation of the polypeptide filament.
The two most studied secondary conformations
of proteins are the alpha-helix and the beta-sheet.

• The isoelectric point of an amino acid is defined
as the pH
A. where the molecule carries no electric charge
B. where the carboxyl group is uncharged
C. where the amino group is uncharged
D. of maximum electrolytic mobility

• When the amino acid alanine (R-group
is CH3) is added to a solution
with a pH of 7.3, alanine becomes
A. a cation
Isoelectric
B. nonpolar
point of
C. a zwitterions
alanine is
D. an anion
6.00

• The term “SALTING IN” refers to?
A. Changes in an amino acid’s isoelectric
point.
B. Increasing the solubility of a protein in
solution by adding ions.
C. The use of a liquid bridge in an
electrochemical cell.
D. The ionization of a strong acid.

Salting Out (by solubility)
• Most proteins are less soluble at high salt concentrations, an effect
called salting out.
• The salt concentration at which a protein precipitates differs from
one protein to another. Hence, salting out can be used to fractionate
proteins.
• Dialysis can be used to remove the salt if necessary.

• The local spatial arrangement of a
polypeptide’s backbone atoms without regard
to the conformation of its side chains can be
called as
A. Primary structure
B. Secondary structure
C. Tertiary structure
D. Quaternary structure

• Which of the following amino acids are
more likely to be found in a protein’s
interior away from aqueous solvent
molecules?
A. Val, Leu, Ile, Met, and Phe
B. Ser, Thr, Asn, Gln, and Tyr
C. Arg, His, Lys, Asp, and Glu
D. All of the above.

• Which of the following is (are) true of b-
turns in proteins?
A. It is a 180º turn of four amino acids.
B. Glycine and proline are frequently
found there.
C. Are used as connecting turns of a-
helix
D. All of the above.

• The primary stabilizing force of
protein secondary structure is:
• A Ionic bonds.
• B Covalent bonds.
• C Van der Waals forces.
• D Hydrogen bonds

• Two types of b-pleated sheets can be
called:
• A parallel and antiparallel
• B left-handed and right-handed.
• C Fand Y
• D α and β

• Which of the following is NOT a characteristic
of a globular protein?
• A Polypeptide chain in extended, long
sheets
• B Polypeptide chains are folded in a
spherical shape.
• C Contains several types of secondary
structure
• D Typical for regulatory proteins.

• Which of the following statements regarding
ligand binding is NOT correct?
A. Some proteins require ligands in order to
perform their function
B. Enzymes with their attached ligands are
called holoenzymes
C. Ligands are synonymous with prosthetic
groups
D. The heme group on hemoglobin is an
example of a tightly bound ligand

• The alpha helix found in myoglobin can
best be described as
A. Primary structure
B. Secondary structure
C. Tertiary structure
D. Motif structure

• Some parts of a protein that have a specific
chemical structure and function are called
protein
A. chemicals
B. domains
C. subunits
D. enzymes

• One of the following is NOT usually a
force that helps to hold the monomer
units of a quaternary protein together?
A. Peptide bonds
B. Disulfide bonds
C. Salt bonds
D. Hydrophobic interactions

What is the quaternary structure of a protein?
Do all proteins have quaternary structure?
• The quaternary protein structure is the spatial
conformation due to interactions among
polypeptide chains that form the protein.
• Only those proteins made of two or more
polypeptide chains have quaternary structure.

What is protein denaturation? Is there any
change in the primary structure when a protein
is denatured? What are some factors that can
lead to protein denaturation?
• Secondary, tertiary and quaternary structures of proteins
are spatial structures. Denaturation is modification in any
of these spatial structures that makes the protein
deficient or biologically inactive.
• After denaturation the primary protein structure is not
affected.
• Protein denaturation can be caused by temperature
variation, pH change, changes in the concentration of
surrounding solutes. Most proteins denature after certain
elevation of temperature or when in very acid or very
basic solutions.

• Which of the following terms describes
hemoglobin but not myoglobin?
A. The protein contains hydrogen bonds
B. The protein contains a hydrophobic
pocket that contains heme
C. Imidazole groups stabilize the ferrous
ion
D. The protein contains alpha and beta
chains

• Of the following states of hemoglobin
(Hb), which is least likely to bind the next
molecule of oxygen (O2)?
A. Hb
B. Hb (O2)
C. Hb (O2)2
D. Hb (O2)3

• If a person breathes into a paper bag, you
would expect their blood CO2 to
A. decrease and their blood pH to increase
B. decrease and their blood pH to decrease
C. increase and their blood pH to increase
D. increase and their blood pH to decrease

• The quaternary structure of a protein is
A. the sequence of amino acids in the
polypeptide
B. the coiling or folding of the polypeptide
C. the intertwining of two or more polypeptides
D. the 3-dimensional appearance of the
polypeptide

• The action of disrupting the three-dimensional
shape of a protein is
termed
A. dehydration
B. denaturation
C. deamination
D. hydrolysis

SSaammppllee qquueessttiioonnss
• At a pH >pI of a given protein, that protein
becomes ______, at the pH<pI of that
same protein, it becomes _______.
negatively charged (an anion)
positively charged (a cation)
The isoelectric point (pI) is the pH at which a particular molecule or surface
carries no net electrical charge.

SSaammppllee qquueessttiioonnss
• What is the prosthetic group that hemoglobin and
myoglobin's oxygen binding ability depend on?
Heme
• Define cooperativity relative to binding oxygen
binding of oxygen at one site increases chances
of binding oxygen at the other sites; loss of an
oxygen at one site increases the chances of
losing oxygen at the other sites
• What are the two states of the hemoglobin quaternary
structure? And what are their characteristics?
T state = taut (deoxy form)
R state = relaxed (oxygenated form)

Sample questions
• The imino acid found in protein structure
• (a) Arginine
• (b) Proline
• (c) Histidine
• (d) Lysin

• The bonds in protein structure that are
not broken on denaturation.
• (a) Hydrogen bonds
• (b) Peptide bonds
• (c) lonic bond
• (d) Disulfide bonds

• Which of the following
is not considered a
pyrimidine?
A. C
B. T
C. U
D. G
• What type of sugar is
found in the
nucleotides of DNA?
A. deoxyribose
B. ribose
C. glucose
D. none of the above

• What is the role of hydrogen bonds in
the structure if DNA?
A. to code for proteins
B. to synthesize proteins
C. to separate the strands
D. to connect the base pairs

Which type of chemical bond maintains the
pairing of each chain in the DNA molecule?
• To form the DNA molecule, purine bases
bind to pyrimidine bases by intermolecular
bonds called hydrogen bonds. Hydrogen
bonds occur when there is hydrogen near
one of these electronegative elements:
oxygen or nitrogen.

Sample questions for the nucleic acid section
Nucleoside is a pyrimidine or
purine base
• A.covalently bonded to a
sugar
• B.ionically bonded to a sugar
• C.hydrogen bonded to a sugar
• D.none of the above
The sugar in RNA is ______ , the
sugar in DNA is _____
• A.deoxyribose, ribose
• B.ribose, deoxyribose
• C.ribose, phosphate
• D.ribose, uracil

In gel electrophoresis, what
fragments will move most
quickly through a gel?
• A.Large fragments
• B.Small fragments
• C.Large genome
• D.None of these
Nucleotide bases and
aromatic amino acids
absorb light respectively at
• A.280 and 260 nm
• B.260 and 280 nm
• C.270 and 280 nm
• D.260 and 270 nm

Which of the following is found
on RNA but not DNA?
• A.Uracil
• B.Deoxyribose
• C.Phosphate
• D.Adenine
Which is true about the pairing of
bases in the DNA molecule?
• A. purines always pair with
pyrimidines
• B. a single ring base pairs with
another single ring base
• C. a double ring base pairs with
another double ring base
• D. purines pair with purines and
pyrimidines with pyrimidines

A messenger acid is 336 nucleotides
long, including the initiator and
termination codons. The maximum
number of amino acids in the
protein translated from this mRNA
is:
• A 999
• B 630
• C 330
• D 111
• E 110
With what mRNA codon would the
tRNA in the diagram be able to
form a codon-anticodon base
pairing interaction?
• A. 3'-AUG-5'
• B. 3'-GUA-5'
• C. 3'-CAU-5'
• D. 3'-UAC-5'
• E. 3'-UAG-5'

• Of what units are nucleic acids constituted? What are the
chemical entities that compose that unit?
• What is the rule for the pairing of nitrogenous bases in
the DNA molecule? And in the RNA?
• For each of the following structures identify: the
carbohydrate (ribose or deoxyribose)?; nucleoside or a
nucleotide? DNA or a RNA system?

Sample questions
What is the function of enzymes within living systems?
• A) structural elements
• B) neurotransmitters
• C) catalysts
• D) hormones
Enzymes have names that
• A) always end in -ase
• B) always end in -in
• C) can end either in -in or -ase
• D) can end in either -in or -ogen

Sample questions
The protein portion of a conjugated enzyme is called a(n)
• A) apoenzyme.
• B) coenzyme.
• C) holoenzyme.
• D) cofactor.
Which of the following could be a component of a conjugated enzyme?
• A) coenzyme
• B) cofactor
• C) apoenzyme
• D) more than one correct response
• E) no correct response

Sample questions
Enzyme cofactors that bind covalently at the active site of an enzyme
are referred to as _________.
• (a) cosubstrates.
• (b) prosthetic groups.
• (c) apoenzymes.
• (d) vitamins

Sample questions
Which of the following statements concerning the effect of temperature
change on an enzyme-catalyzed reaction is correct?
• A) An increase in temperature can stop the reaction by denaturing
the enzyme.
• B) An increase in temperature can increase the reaction rate by
increasing the speed at which molecules move.
• C) An increase in temperature to the optimum temperature
maximizes reaction rate.

Sample questions
• A catalyst can promote product formation during a chemical reaction
by _____.
• (a) lowering the activation energy barrier.
• (b) stabilizing the transition state.
• (c) positioning reactants in the correct orientation.
• (d) bringing reactants together.
• (e) all of the above
Which of the following is characteristic of an enzyme catalyst?
• (a) It positions reactants in the correct orientation.
• (b) It lowers the activation energy barrier.
• (c) It binds the transition state tighter than the substrate.
• (d) all of the above

Sample questions
An enzyme active site is the location in the enzyme where
• A) protein side groups are brought together by bending and folding
to form a site for interactions with substrates
• B) the catalyst interactions with the enzyme
• C) catalyst molecules are generated
• D) the substrate creates the catalyst molecules
An enzyme active site is the location in an enzyme where substrate
molecules
• A) are generated.
• B) become catalysts.
• C) undergo change.

• For the enzyme reaction A+ B = C + D, Delta Go' = + 1
kcal/mol. This reaction will proceed spontaneously in a
forward direction if:
A. The concentration of C is increased one-hundred fold
B. The concentration of A is increased one-hundred fold
C. The concentration of B is lowered one-hundred fold
D. The concentration of both A and D are increased one-hundred
fold

• Which of the following statements about enzymes or
their function is true?
A. Enzymes do not alter the overall change in free
energy for a reaction
B. Enzymes are proteins whose three-dimensional form
is key to their function
C. Enzymes speed up reactions by lowering activation
energy
D. All of the above

• What is the optimal temperature range
for the majority of enzymes?
A. 40-55 ℃
B. 35-40 ℃
C. 25-30 ℃
D. 15-20 ℃

• An allosteric activator
A. increases the binding affinity
B. decreases the binding affinity
C. stabilizes the R state of the protein
D. both (a) and (c)

• Reactants of an enzyme-catalyzed
reaction are known as
A. products
B. substrates
C. proteins
D. complex

• The location on an enzyme where
binding occurs is known as the
A. action point
B. enzyme
C. binding location
D. active site

• Enzymes catalyze reactions by
A. Increasing the free energy of the system so that the
change in free energy is positive
B. Increasing the free energy of the substrate so that it is
greater than the free energy of the product
C. Changing the equilibrium constant for the reaction
D. Decreasing the free energy of activation

• An apoenzyme
A. Includes non-protein compounds such as metal ions
B. Consists of complex organic structures which may be
classified as activation-transfer coenzymes or oxidation-reduction
coenzymes
C. Is the protein portion of the enzyme without the
cofactors
D. None of the above

• NAD+, FAD, and FMN are all cofactors
for:
A. Oxidoreductases
B. Transferases
C. Hydrolases
D. Ligases

• At the end of a chemical reaction
A. an enzyme's structure is altered
B. an enzyme is detached from the product,
has its original structure, and can catalyze
more chemical reactions
C. the enzyme loses its ablity to catallyze other
chemical reactions
D. the enzyme remains attached to the
products

Sample questions
The rate of a second order reaction depends on the concentration of
_________.
• (a) one substrate
• (b) two substrates
• (c) three substrates
• (d) none of the above

Rate constants and reaction order
Rate constant (k) measures how rapidly a reaction occurs
k1
k-1
A B + C
Rate (v, velocity) = (rate constant) (concentration of reactants)
v= k1 [A]
1st order reaction (rate dependent on concentration of 1 reactant)
v= k-1[B][C]
2nd order reaction (rate dependent on concentration of 2 reactants)
Zero order reaction (rate is independent of reactant concentration)

• On the following plot, N represents the curve for an
allosteric enzyme with no allosteric activators or
inhibitors added. If an allosteric activator was added,
which curve would one obtain?
A. Curve A
B. Curve B
C. Curve C
D. Curve D

• Which of the following statements about
allosteric enzymes is CORRECT?
A. The binding of substrate to any active site
affects the other active sites
B. The plot of initial velocity vs. substrate
concentration is a straight line
C. The Keq of the reaction is increased when
allosteric activator is bound
D. The enzymes contains only one polypeptide
chain

Sample questions
Which of the following kinetic parameters best describes how
well suited a specific compound functions as a substrate
for a particular enzyme?
• (a) Km
• (b) Vmax
• (c) kcat
• (d) kcat/Km

Short summary
• Km  substrate specificity; substrate binding
• kcat,  the turnover number
• kcat/Km  the catalytic efficiency

Sample questions
The rate-determining step of Michaelis Menten kinetics is
• A.the complex formation step
• B.the complex dissociation step to produce product
• C.the product formation step
• D.Both (a)and(c)

• A competitive inhibitor of an enzyme works by
A. fitting into the enzyme's active site
B. fitting into the allosteric site of the enzyme
C. attaching itself to the substrate, thereby preventing
the enzyme from making contact with substrate
D. increasing the activation energy of the enzyme-catalyzed
reaction

• If an enzyme is described by the Michaelis-
Menten equation, a competitive inhibitor will:
A. decrease the Km and decrease the Vmax
B. decrease the Km, but not the Vmax
C. always just change the Vmax
D. increase the Km but not change the Vmax

• The most likely effect of a non-competitive
inhibitor on an Michaelis-Menten enzyme
is to
A. Increase the Vmax
B. Decrease the Vmax
C. Increase both the Vmax and the Km
D. Decrease both the Vmax and the Km

• Competitive inhibitor: Vmax stays the same, but Km increases
• Non-competitive inhibitor decreases the turnover number of the
enzyme rather than preventing substrate binding- Vmax decreases
but Km stays the same. This cannot be overcome with an increase
in substrate concentration.

Sample questions
Which of the following binds to an enzyme at its active site?
• A) irreversible inhibitor
• B) reversible competitive inhibitor
• C) reversible noncompetitive inhibitor
An uncompetitive inhibitor binds to _____.
• (a) E
• (b) ES
• (c) P
• (d) a and b
• (e) a and c

Questions of biochemistry with answers of all chapter

Sample questions
A reversible inhibitor that can bind to either E alone or the ES complex
is referred to as a _____.
• (a) competitive inhibitor.
• (b) non-competitive inhibitor.
• (c) uncompetitive inhibitor.
• (d) suicide inhibitor.
• (e) irreversible inhibitor.

Sample questions
A competitive inhibitor of an enzyme is usually
• A.a highly reactive compound
• B.a metal ion such as Hg2+ or Pb2+
• C.structurally similar to the substrate.
• D.water insoluble
The enzyme inhibition can occur by
• A.reversible inhibitors
• B.irreversible inhibitors
• C.Both (a) and (b)
• D.None of these

Sample questions
In a Lineweaver-Burk Plot, competitive
inhibitor shows which of the following
effect?
• A.It moves the entire curve to right
• B.It moves the entire curve to left
• C.It changes the x-intercept
• D.It has no effect on the slope

Sample questions
Non-competitive inhibitor of an enzyme catalyzed
reaction
• A.decreases Vmax
• B.binds to ES
• C.both (a) and (b)
• D.can actually increase reaction velocity in rare
cases

Sample questions
A classical uncompetitive inhibitor is a compound that binds
• A.reversibly to the enzyme substrate complex yielding an
inactive ESI complex
• B.irreversibly to the enzyme substrate complex yielding an
inactive ESI complex
• C.reversibly to the enzyme substrate complex yielding an
active ESI complex
• D.irreversibly to the enzyme substrate complex yielding an
active ESI complex

Sample questions
• Two curves showing the rate versus substrate concentration are
shown below for an enzyme catalyzed reaction. One ‐ curve is for the
reaction in the presence of substance X. The other curve is for data
in the absence of substance X. Examine the curves and tell which
statement below is true.
• A) The catalysis shows Michaelis‐Menten kinetics with or without X.
• B) X increases the activation energy for the catalytic reaction.
• C) X could be a competitive inhibitor.
• D) X is an activator of the enzyme.

Sample questions
Allosteric enzymes are
• A.similar to simple enzyme
• B.smaller than simple enzyme
• C.larger and more complex than simple enzyme
• D.smaller than simple enzyme but not complex
Which statement is false about allosteric regulation?
• A. It is usually the mode of regulation for the last step in reaction pathways
since this step produces the final product.
• B. Cellular response is faster with allosteric control than by controlling
enzyme concentration in the cell.
• C. The regulation usually is important to the conservation of energy and
materials in cells.
• D. Allosteric modulators bind non-covalently at sites other than the active
site and induce conformational changes in the enzyme.

Sample questions
Allosteric modulators seldom resemble the substrate or
product of the enzyme. What does this observation
show?
• A) Modulators likely bind at a site other than the active
site.
• B) Modulators always act as activators.
• C) Modulators bind non-covalently to the enzyme.
• D) The enzyme catalyzes more than one reaction.

Sample questions
• Some enzymatic regulation is allosteric. In such cases,
which of the following would usually be found?
• A) cooperativity
• B) feedback inhibition
• C) both activating and inhibitoryactivity
• D) an enzyme with more than one subunit
• E) the need for cofactors

Sample questions
• Describe allosteric regulation of
enzyme activity?
An allosteric enzyme is one in which the activity of the enzyme can be
controlled by the binding of a molecule to the “allosteric site”, somewhere
other than the active site. Thus allosteric control of an enzyme can be
classed in two ways. A positive allosteric regulation is the binding of a
molecule to the enzyme which increase the rate of reaction. The opposite is
a negative allosteric regulation. An example for this is phosphofructokinase,
which is promoted by a high AMP concentration, and inhibited by a high ATP
concentration.

• This small protein can have dramatic
effects on the activities of enzymes in
response to changes in intracellular
calcium ion concentration:
A. Calcitonin
B. Calsequestrin
C. Calmodulin
D. Calcitriol

Non-covalent Interactions
Protein-Protein Interactions
• Calmodulin (CALcium MODULted proteIN)
– Binding of Ca++ to calmodulin changes its
shape and allows binding and activation of
certain enzymes

Sample questions
• Which statement is false about covalent modification?
• A) It is reversible.
• B) It is slower than allosteric regulation.
• C) It is irreversible.
• D) Phosphorylation is a common covalent modification.

Sample questions
Protein kinases are enzymes that act on other enzymes by
adding phosphates groups. When the enzyme is
phosphorylated, it changes its activity (it becomes more
or less active, depending on the enzyme). This
regulatory mechanism of enzymatic activity is called:
• A) Allosteric Control
• B) Competitive inhibition
• C) Covalent Modification
• D) Isozymes Modification
• E) Zymogen activation

Sample questions
• Glycolytic pathway regulation involves
• A. allosteric stimulation by ADP
• B. allosteric inhibition by ATP
• C. feedback, or product, inhibition by ATP
• D. all of the above
• Why does the glycolytic pathway continue in the direction of
glucose catabolism?
• A. There are essentially three irreversible reactions that act as the
driving force for the pathway
• B. High levels of ATP keep the pathway going in a forward
direction
• C. The enzymes of glycolysis only function in one direction
• D. Glycolysis occurs in either direction

Sample questions
The released energy obtained by oxidation of glucose is stored as
A. a concentration gradient across a membrane
B. ADP
C. ATP
D. NAD+
A kinase is an enzyme that
A. removes phosphate groups of substrates
B. uses ATP to add a phosphate group to the substrate
C. uses NADH to change the oxidation state of the substrate
D. removes water from a double bond

Sample questions
• For every one molecule of sugar glucose which is oxidized
__________ molecule of pyruvic acid are produced.
• A.1
• B.2
• C.3
• D.4
• The enzymes of glycolysis in a eukaryotic cell are located in the
• A.intermembrane space
• B.plasma membrane
• C.cytosol
• D.mitochondrial matrix

Sample questions
• Which of the following is not true of glycolysis?
• A.ADP is phosphorylated to ATP via substrate level
phosphorylation
• B.The pathway does not require oxygen
• C.The pathway oxidizes two moles of NADH to NAD+ for each mole
of glucose that enters
• D.The pathway requires two moles of ATP to get started
catabolizing each mole of glucose
• ATP is from which general category of molecules?
• A.Polysaccharides
• B.Proteins
• C.Nucleotides
• D.Amino acids

Sample questions
• Which of the following regulates glycolysis steps?
• A.Phosphofructokinase
• B.Hexose kinase
• C.Pyruvate kinase
• D.All of these

Sample questions
• Which of the following is not a mechanism for altering the flux of
metabolites through the rate-determining step of a pathway?
• A. Allosteric control of the enzyme activity
• B. Block active sites
• C. Genetic control of the enzyme concentration
• D. Covalent modification of the enzyme
• Phosphofructokinase, the major flux-controlling enzyme of
glycolysis is allosterically inhibited and activated respectively by
• A.ATP and PEP
• B.AMP and Pi
• C.ATP and ADP
• D.Citrate and ATP

• Where does glycolysis occur?
A. inner membrane of mitochondria
B. matrix of mitochondria
C. stroma of chloroplast
D. cytoplasm

• Sports physiologists wanted to monitor
athletes to determine at what point their
muscles were functioning anaerobically. They
could do this by checking for a buildup of
which of the following compounds?
A. oxygen
B. ATP
C. lactate
D. carbon dioxide

Sample questions
• There are four enzymes of gluconeogenesis that
circumvent the irreversible steps in glycolysis. When
starting with the substrate pyruvate or lactate they are
• A. Hexokinase, phosphofructokinase-1,
phosphofructokinase-2 and pyruvate kinase
• B. Pyruvate carboxylase, phosphoenolpyruvate
carboxykinase, fructose-1,6-bisphosphatase, and
glucose-6-phosphatase
• C. Glycerol kinase, glycerol-3-phosphate
dehydrogenase, fructose-2,6-bisphosphatase, and
• D. Amino transferase, phosphoenolpyruvate
carboxykinase, fructose-2,6-bisphosphatase, and

Sample questions
• The enzymes that remove phosphate groups during the
process of gluconeogenesis and circumvent two of the
three irreversible reactions of glycolysis are
• A. Pyruvate kinase and glycerol kinase
• B. Phosphoenolpyruvate carboxykinase and glycerol
kinase
• C. 3-Phosphoglycerate kinase and fructose-1,6-
bisphosphatase
• D. Fructose-1,6-bisphosphatase and glucose-6-
phosphatase

Glycolysis <-> gluconeogenesis
Gluconeogenesis is not the reversal of glycolysis !!!
Glycolysis: in the cytosol
Gluconeogenesis: major part in cytosol
-> 1st step in mitochondria -> shuttle
Biotin: prosthetic
group -> carrier
for CO2
Reverse reaction of glycolysis thermodynamically
not favorable !!!
112

Sample questions
• The most important control step in gluconeogenesis is fructose-1,6-
bisphosphatase. All of the following statements are true EXCEPT
• A. Fructose-1,6-bisphosphatase converts fructose-2,6-bisphosphate
to fructose-6-phosphate
• B. During times when insulin is high, fructose-1,6-bisphosphatase is
inhibited by fructose-2,6-bisphosphate
• C. During a fast or exercise when glucagon and/or epinephrine are
high, fructose-1,6-bisphosphatase is active because of the absence
of fructose-2,6-bisphosphate
• D. Glycolysis or gluconeogenesis cannot be active at the same
time. If they were is would be a futile cycle

Sample questions
• In the liver, glucagon will activate
• A. Glycolysis and glycogen synthesis
• B. Gluconeogenesis and glycogenolysis
• C. Gluconeogenesis and glycogen synthase
• D. Gluconeogenesis and glycogen synthesis
• Which of the following statements about hormonal levels during different
states is true?
• A. During the time you are eating a high carbohydrate mixed meal, the
insulin to glucagon ratio will decrease
• B. When passing from the fed to fasting state, insulin and glucagon usually
decrease
• C. When playing basketball, epinephrine is usually low and insulin is high
• D. After running for 20 miles, epinephrine and glucagon are high and insulin
is low

Sample questions
• All of the following will result in activation of glycogen
phosphorylase in skeletal muscle EXCEPT
• A. Increased concentrations of AMP from contraction of
muscle
• B. Increased epinephrine and cAMP
• C. Increased cytosolic [Ca++]
• D. Increased protein phosphatase
• E. Increased activity of glycogen phosphorylase kinase

• All of the following statements concerning glycogen
synthesis and glycogenolysis are true EXCEPT
A. High blood glucose and high insulin will activate
glycogen synthesis and inhibit glycogen phosphorylase
B. A low insulin to glucagon ratio will activate glycogen
phosphorylase and inhibit glycogen synthase
C. Being hit in the head with a bat will activate glycogen
synthesis and inhibit glycogen phosphorylase
D. Taking this test will activate glycogen phosphorylase
and inhibit glycogen synthase

Sample question
• Atherosclerosis can cause blood
• A. thinning
• B. blockage
• C. thickening
• D. none of these

Sample question
• Ketosis is ascribed in part to:
– A. Slowdown in fat metabolism
– B. An insufficient intermediates of TCA cycle
– C. An underproduction of acetyl-CoA
– D. An inhibition of glycogen synthesis

Sample question
• In the intestine, the dietary fats are hydrolyzed by
• A.triacylglycerol lipase
• B.adenylate cyclase
• C.pancreatic lipase
• D.protein kinase

Sample question
• In eukaryotes fatty acid breakdown occurs in
• A. mitochondrial matrix
• B. cytosol
• C. cell membrane
• D. endoplasmic reticulum

Sample question
• Fatty acid synthesis takes place in
• A. mitochondria
• B. cell membrane
• C. cytosol
• D. endoplasmic reticulum

Sample question
• Chylomicrons are synthesized in
• A. blood
• B. liver
• C. intestine
• D. pancreas

Sample question
• VLDLs are synthesized in
• A. blood
• B. liver
• C. intestine
• D. pancreas

Sample question
• Cholestrol is the precursor of
• A. steroid hormones
• B. vitamin A
• C. bile salts
• D. both (a) and (c)

Sample Questions
• A biological redox reaction always involves
• A.an oxidizing agent
• B.a gain of electrons
• C.a reducing agent
• D.all of these
• Coenzyme Q is involved in electron transport as
• A.directly to O2
• B.a water-soluble electron donor
• C.covalently attached cytochrome cofactor
• D.a lipid-soluble electron carrier

Sample Questions
• FAD is reduced to FADH2 during
• A. electron transport phosphorylation
• B. lactate fermentation
• C. Krebs cycle
• D. glycolysis
• During glycolysis, electrons removed from glucose
are passed to
• A. FAD
• B. NAD+
• C. acetyl CoA
• D. pyruvic acid

Sample Questions
• Almost all of the oxygen (O2) one consumes in
breathing is converted to:
• A.acetyl-CoA.
• B.carbon dioxide (CO2).
• C.carbon monoxide and then to carbon dioxide.
• D.water.
• The carbon dioxide is primary a product of
• A.Krebs cycle
• B.glycolysis
• C.electron transport phosphorylation.
• D.lactate fermentation.

Sample Question
• Which of the following statements about the chemiosmotic theory
is correct?
• A. Electron transfer in mitochondria is accompanied by an
asymmetric release of protons on one side of the inner
mitochondrial membrane.
• B. It predicts that oxidative phosphorylation can occur even in
the absence of an intact inner mitochondrial membrane.
• C. The effect of uncoupling reagents is a consequence of their
ability to carry electrons through membranes.
• D. The membrane ATP synthase has no significant role in the
chemiosmotic theory.

Sample Question
• Uncoupling of mitochondrial oxidative
phosphorylation:
• A. allows continued mitochondrial ATP
formation, but halts O2 consumption.
• B. halts all mitochondrial metabolism.
• C. halts mitochondrial ATP formation, but
allows continued O2 consumption.
• D. slows the conversion of glucose to
pyruvate by glycolysis.

Sample Questions
• Where does Oxidative Phosphorylation
occur?
the inner membrane of the cell mitochondria
• In the reaction in which FADH2 transfers
hydrogen atoms to Q, which molecule is
oxidized and which is reduced?

• Cellular respiration takes place
mostly in:
A. chloroplasts
B. ribosomes
C. nucleus
D. mitochondria

• Which of the following is not present
during the TCA cycle?
A. NADH
B. O2
C. CO2
D. ATP

• Which of the following is a list of the stages in
the correct order?
A. pyruvate oxidation, glyocolysis, the citric acid
cycle, and oxidative phosphorylation
B. oxidative phosphorylation, glyocolysis, the
citric acid cycle, and pyruvate oxidation
C. glycolysis, pyruvate oxidation, the citric acid
cycle, and oxidative phosphorylation
D. glycolysis, the citric acid cycle, pyruvate
oxidation, and oxidative phosphorylation

• What are the products of the citric
acid cycle?
A. NADH, ATP, FADH2, and CO2
B. O2, ADP, 1 FAD, and NAD+
C. Glucose, ATP, O2, and NADH
D. heat, H2O, NADH, and pyruvate

• Which of the following is NOT a way of
producing ATP in humans?
A. Krebs Cycle
B. Alcohol Fermentation
C. Lactic Acid Fermentation
D. Glycolysis

• Which of the following is an aerobic
product of pyruvate catabolic
metabolism?
• A lactate
• B ethanol.
• C acetyl CoA
• D glucose.

• Someone had hypoglycemic coma after he
injected himself with a large dose of insulin. All
of the following contributed to his coma EXCEPT
A. Insulin inhibited gluconeogenesis in the liver
B. Insulin activated glycogen phosphoryalse in
the liver
C. Insulin increased Glut4 in the muscle
membrane
D. Insulin inhibited the mobilization of free fatty
acid from adipose and the entrance into liver
mitochondria

• The insulin to glucagon ratio is low as it usually is in both
Type I and Type II diabetics. During and immediately
after a high carbohydrate meal, you would expect
A. The storage of glucose in muscle to be less than
normal for type 2 patients but normal for type 1 patients
B. The storage of glucose in muscle to be less than
normal for type 1 patients but normal for type 2 patients
C. The storage of glucose in muscle and liver to be less
than normal
D. The storage of glucose in muscle and liver to be
greater than normal

• All other things being constant, an
increase in glucagon would result in an
increase in
A. Fatty acid synthesis in adipose tissue
B. β-oxidation in liver
C. Protein synthesis in muscle
D. Glycogenolysis in muscle

• The pathway for the synthesis of glycogen
from portal blood glucose in the liver:
A. Is inhibited by glucose
B. Is inhibited by insulin
C. Uses activated glycogen phosphorylase
D. Is inhibited by high cAMP

• Epinephrine:
• A stimulates the synthesis of glycogen in
liver cells.
• B has no effect on cAMP in muscle cells
• C has a direct effect on the glucose
transporter in muscle cells.
• D stimulates the degradation of glycogen
in muscle cells.

• The TCA cycle:
A. Is found in the cytosol
B. Is controlled by the ADP/ATP ratio and the
NADH concentration
C. Is also called the Cori cycle
D. Produces most of the water made in humans

• The Krebs Cycle begins when pytuvic acid
produced by glycolsis enters the
A. cytosol
B. air
C. mitochondrion
D. nuclear

• During the fasting state, the release of fatty
acids from adipose tissue is increased. At least
part of the signal for this release is carried by
A. insulin from beta-cells of the pancreas
B. epinephrine from alpha-cells of the pancreas
C. epinephrine from the adrenal medulla
D. glucagon from the adrenal medulla

• In aerobic organisms growing in the
presence of oxygen, the NADH produced by
glycolysis ultimately donates its high-energy
electrons to .
A. electron transport chains in the
mitochondria
B. ATP
C. pyruvate
D. glucose

• Cellular respiration takes place mostly
in:
A. chloroplasts
B. ribosomes
C. nucleus
D. mitochondria

• The main purpose of the electron transport
chain is to:
A. Use high energy electrons from other
cycles to convert ADP into ATP
B. Maintain a stable balance of high energy
electrons
C. Constantly distribute electrons throughout
the cell
D. Tell the cell when glycolysis should stop or
start

• Oxidative phosphorylation:
A. Is anaerobic
B. Requires AMP
C. Requires the electron transport system
D. Is not dependent upon development of
a proton gradient

• Where are the proteins of the electron
transport chain located?
A. cytosol
B. mitochondrial outer membrane
C. mitochondrial inner membrane
D. mitochondrial matrix

• The ATP synthase responsible for most of the
ATP synthesis in the body is located:
A. On the outer side of the outer mitochondria
membrane
B. On the inner side of the outer mitochondria
membrane
C. On the outer side of the inner mitochondria
membrane
D. On the inner side of the inner mitochondria
membrane

• In the electron transport chain, the final
electron acceptor is
A. oxygen
B. a molecule of carbon dioxide
C. a molecule of water
D. ADP

• A mitochondrion is producing ATP at a constant
rate and, then, a chemical uncoupler is added.
Compared to before the uncoupler was added:
A. Less heat would be produced
B. Less water would be produced
C. More NADH would be oxidized
D. The proton gradient across the membrane
would be increased

Matrix
H+
+ NADH NAD+
+ 2H+ 2H+
+ ½ O2 H2O
2 e-
I Q III IV
cyt c
uncoupler
4H+ 4H+ 2H+ H+
Intermembrane Space
With uncoupler present, there is no DpH or DY.
 DG for H+ ejection is zero
 DG for e- transfer coupled to H+ ejection is maximal
(spontaneous).
Respiration proceeds in the presence of an uncoupler,
whether or not ADP is present.

• A direct inhibitor of the ATP synthase (i.e.
the ability to make ATP) in the presence of
active electron transport:
• A. would increase the membrane potential.
• B would decrease the membrane potential.
• C would increase electron transport rates
• D would decrease the pH gradient.

• During chemiosmosis,
A. energy is released as H+ ions move across
mitochondrial membranes
B. H+ do NOT play any role in the production of ATP
molecules
C. a concentration gradient is generated when large
numbers of H+ ions are passively transported from the
matrix of the mitochondrion to the mitochondrion's
intermembrane space
D. ATP is synthesized when H+ ions move through a
channel in ATP synthase

• The chemiosmotic theory holds all of the following
EXCEPT:
A. The cytosol has a higher pH than the matrix
B. In the absence of a proton motive force, ATP will not
be synthesized
C. The electrochemical potential comes from both the
electrical potential and the proton concentration gradient
D. Electrons are passed from one carrier to the next as
protons are pumped across the inner mitochondrial
membrane

• During REDOX reactions in cellular
respiration, glucose undergoes _____
while oxygen undergoes______
A. reduction ..... oxidation
B. oxidation ..... reduction
C. no change ..... oxidation
D. none of the above

• Anemia, hemorrhage, and chronic obstructive pulmonary disease
can all cause metabolic acidosis. The best explanation is that the
lack of oxygen causes
A. a decrease in insulin that, in turn, increases anaerobic glycolysis
in the brain
B. a decrease in oxidative phosphorylation so the cells have to rely
upon anaerobic glycolysis
C. a decrease in the removal of CO2 from the blood. The resulting
decrease in pH causes an increase in glycolysis in most cells
D. an increase in glycolysis in red blood cells

• Hydrolysis of a triglyceride produces
A. many amino acids
B. different types of nucleotides
C. fatty acids and glycerol
D. monosaccharides

• Free fatty acids are able to travel from
adipose tissue to muscle or liver
A. As independent water soluble
compounds in the blood
B. By using receptors on red blood cells
C. Bound to serum proteins
D. By using enzymes that modify them

• When the concentration of epinephrine or glucagon is
high, they bind to receptors on adipose cell membrane
and all of the following can be expected to occur
EXCEPT
A. Triacylglycerol is hydrolyzed to free fatty acids and
glycerol
B. Free fatty acids are carried to most tissues of the
body by albumin
C. Fatty acids are activated, enter the mitochondria, and
are oxidized by β-oxidation and the TCA cycle
D. Increased β-oxidation increases glycolysis in resting
muscle

Sample question
• The site of amino acid catabolism is the:
A. Stomach
B. Small intestine
C. Large intestine
D. Liver

Sample question
• The first step in the catabolism of most amino
acids is
• A. Removal of carboxylate groups
• B. Enzymatic hydrolysis of peptide bonds
• C. Removal of the amino group
• D. Zymogen cleavage

Sample question
Which of the following is true of urea?
• A. more toxic to human cells than ammonia
• B. the primary nitrogenous waste products of
humans.
• C. insoluble in water
• D. the primary nitrogenous waste product of
most aquatic invertebrates

Sample question
A glucogenic amino acid is one which is
degraded to
• A. keto-sugars
• B. either acetyl CoA or acetoacetyl CoA
• C. pyruvate or citric acid cycle
intermediates
• D. none of the above

Sample question
Transamination is the process where
• A. carboxyl group is transferred from amino
acid
• B. α-amino group is removed from the amino
acid
• C. polymerization of amino acid takes place

Sample question
Transamination is the transfer of an amino
• A. acid to a carboxylic acid plus ammonia
• B. group from an amino acid to a keto acid
• C. acid to a keto acid plus ammonia
• D. group from an amino acid to a carboxylic
acid

Sample Question
• In inherited deficiency of hypoxanthine
guanine phosphoribosyl transferase
(A) De novo synthesis of purine nucleotides is
decreased
(B) Salvage of purines is decreased
(C) Salvage of purines is increased
(D) Synthesis of uric acid is decreased

Sample Question
• Which of the following is a required
substrate for purine biosynthesis ?
(A) 5- methyl thymidine
(B) Ribose phosphate
(C) PRPP
(D) 5-Fluoro uracil

Sample Question
• The conversion of Inosine mono phosphate
(A) To Adenosine mono phosphate (AMP) is
inhibited by Guanosine mono phosphate (GMP)
(B) To AMP requires uridine mono phosphate
(UMP)
(C) To GMP requires GMP kinase
(D) To GMP requires Glutamine

HN
N
O
N N
Ribose-P
Aspartate + GTP
N
N
NH
N N
Ribose-P
COO-
-OOC
HN
N
O
N N
Ribose-P
O
H
Adenylosuccinate xanthine monophosphate
XMP
IMP
IMP dehydrogenase
NAD+
NADH
A.S.
synthetase
GDP
N
N
NH2
N N
Ribose-P
HN
N
O
N N
H2N
Ribose-P
A.S.
lyase
fumarate
glutamine + ATP
Glutamate + AMP
+ PPi
AMP GMP
Synthesis of adenine
and guanine nucleotides
IMP to AMP and GMP
• Glutamine,
NAD, ATP used
in GMP
production
• Aspartate, GTP
used AMP
production

Sample questions
• Both strands of DNA serve as
templates concurrently in
• A. replication
• B. excision repair
• C. mismatch repair

• Proofreading activity to maintain the fidelity of
DNA synthesis
• A. occurs after the synthesis has been completed
• B. is a function of the 3'-5' exonuclease activity of the
DNA polymerases
• C. requires the presence of an enzyme separate from
the DNA polymerases
• D. occurs in prokaryotes but not eukaryotes

• Which of the following repairs nicked DNA by forming a
phosphodiester bond between adjacent nucleotides?
• A. Helicase
• B. DNA gyrase
• C. Topoisomerases
• D. DNA ligase

• The replication of chromosomes by eukaryotes occurs in
a relatively short period of time because
• A. the eukaryotes have more amount of DNA for
replication
• B. the eukaryotic replication machinery is 1000 times
faster than the prokaryotes
• C. each chromosome contains multiple replicons
• D. eukaryotic DNA is always single stranded

• During which of the following process a new
copy of a DNA molecule is precisely
synthesized?
• A. Trasformation
• B. Transcription
• C. Translation
• D. Replication

• Which of the following enzyme adds
complementary bases during replication?
• A. Helicase
• B. Synthesase
• C. Replicase
• D. Polymerase

• Which of the following enzymes unwind short stretches
of DNA helix immediately ahead of a replication fork?
• A. DNA polymerases
• B. Helicases
• C. Single-stranded binding proteins
• D. Topoisomerases

• Which DNA polymerase removes RNA primers
in DNA synthesis?
• A. Polymerase I
• B. Polymerase II
• C. Polymerase III

DNA polymerases are specialized for different roles in
the cell

• Enzyme, responsible for proofreading base
pairing is
• A. DNA polymerase
• B. Telomerase
• C. Primase
• D. DNA ligase

• DNA helicase is used to
• A. unwind the double helix
• B. interact the double helix closely
• C. break a phosphodiester bond in DNA strand

• The synthesis of DNA by DNA polymerase occurs in the
• A. 3' to 5' direction
• B. 5' to 5' direction
• C. 5' to 3' direction
• D. 3' to 3' direction

• The 5' and 3' numbers are related to the
• A. length of the DNA strand
• B. carbon number in sugar
• C. the number of phosphates
• D. the base pair rule

• What is the main damaging effect of UV
radiation on DNA?
• A. Depurination
• B. Formation of thymine dimers
• C. Single strand break
• D. Dehydration

What is the function of DNA polymerase?
Explain how a DNA molecule contains the
information necessary to produce copies of itself.
• DNA polymerase is an enzyme that catalyzes the
reaction that adds nucleotides to a growing DNA
strand while replication occurs. This enzyme also
has a role in repairing errors in DNA molecules.
• Each strand of a DNA molecule serves as a template
for the synthesis of a complementary DNA strand
using base pair relationships. This makes it possible
to produce an exact copy of a DNA molecule.

Sample questions
• Which of the following enzyme is used
for synthesis of RNA under the direction
of DNA?
• A. RNA polymerase
• B. DNA ligase
• C. DNA polymerase
• D. RNA ligase

• Which of the following is a product of
transcription?
• A. mRNA
• B. tRNA
• C. rRNA
• D. all of these

• Recognition/binding site of RNA
polymerase is called
• A. receptor
• B. promoter
• C. facilitator
• D. terminator

• An mRNA transcript of a gene
contains
• A. a start codon
• B. a stop codon
• C. a terminator
• D. all of these

• The components found in all prokaryotic
transcription terminators is
• A. a poly-U region
• B. Rho factor
• C. a hairpin structure

• Where in the cell is the DNA transcribed into
mRNA?
• A.Cytoplasm
• B.Nucleus
• C.Golgi
• D.Cell cytoskeleton

• Which of the following does NOT happen during hnRNA
processing?
• A. Introns are spliced out.
• B. A 7-methylguanosine cap is added to the 5' end of the RNA.
• C. A poly A tail is added.
• D. Ribosomes bind and begin translation.

• Since the two strands of the DNA molecule are
complementary, for any given gene:
• A. The RNA polymerase can bind to either strand.
• B. Only one strand actually carries the genetic code for a
particular gene.
• C. Each gene possesses an exact replica so that no
mutation occurs.
• D. A gene transcribed in the 5’ to 3’ direction on one
strand can be transcribed in the 3’ to 5’ direction on the
other strand.

Sample questions
• The site of protein synthesis is
• A. Ribosome
• B. Nucleus
• C. Endoplasmic reticulum
• D. Chromosome

Sample questions
• The structure in a bacterium that
indicates an active site for protein
synthesis is
• A. a chromosome.
• B. a cell membrane,
• C. a flagellum.
• D. a polysome.

Sample questions
• Which of the following is not
necessary for protein synthesis to
occur, once transcription is
completed?
• A. tRNA
• B. Ribosomes
• C. mRNA
• D. DNA

Sample questions
• During the process of translation:
• A. the peptide is ‘passed’ from the tRNA in the P-site to the tRNA in
the A-site.
• B. incoming tRNAs must first bind to the E-site.
• C. initiation begins with the binding of the ribosomal SSU to the
poly-A tail of the mRNA.
• D. the mRNA is translated by one ribosome at a time.

• The nucleolus of the nucleus is the site
where:
• A. RNA processing occurs
• B. rRNA is transcribed and ribosomal subunits are
assembled
• C. tRNA are charged with amino acids
• D. mRNA is translated into protein

Ribosome Assembly: takes place largely in a specialized domain of
the nucleus, the nucleolus

• The ribosomes are composed of
• A. proteins
• B. RNA
• C. both (a) and (b)
• D. lipids

• Which is required for protein synthesis?
• A. tRNA
• B. mRNA
• C. rRNA
• D. All of these

• In the genetic code there are:
• A. more tRNAs than codons.
• B. more codons than amino acids.
• C. more nucleotides than codons.
• D. the same number of codons and amino
acids

• he anticodon of tRNA
• A. binds to rRNA
• B. binds to an amino acid
• C. binds to the Shine Dalgarno sequence
• D. binds to an mRNA codon

• Initiation of eukaryotic translation begins when
the:
• A. large and small subunits link together, then bind to
the mRNA.
• B. ribosomal small subunit holding an initiator tRNA
binds to the 5’ end of mRNA.
• C. ribosome binds to of the start codon and an initiator
tRNA enters the ribosome.
• D. initiator tRNA binds to the start codon, followed by
binding of the ribosome large subunit.

• On the ribosome, mRNA binds
• A. between the subunits
• B. to the large subunit
• C. to the small subunit

In addition to the APE sites there is an mRNA binding groove
that holds onto the message being translated

• The peptidyl transferase reaction
occurs
• A. on the large subunit
• B. on the small subunit
• C. between the subunit

• Ribosomes select the correct tRNAs
• A. based on the aminoacyl group
• B. solely on the basis of their anticodons
• C. depending on their abundance in the
cytosol
• D. with the least abundant anticodons

• Which of the following amino acid
starts all proteins synthesis?
• A. Glycine
• B. Proline
• C. Thymine
• D. Methionine

• The growing polypeptide chain is released
from the ribosomes when
• A. a chain terminating codon is reached
• B. a chain terminating tRNA binds to the ribosome
• C. the 7-methyl guanosine cap is reached
• D. the poly A tail is reached

What is a gene?
• A gene is a region of DNA whose final product is
either a polypeptide or an RNA molecule

Sample questions
• The lac repressor is a
• A. carbohydrate.
• B. DNA molecule.
• C. RNA molecule.
• D. protein molecule.

• What would be the effect of a mutation in the
operator that blocked the lac repressor binding?
• A. The genes would be inducible by lactose.
• B. The lacZYA genes would be expressed
constitutively.
• C. The lacZYA genes would not be expressed.
• D. The lacZYA genes would be repressed by lactose.

• A regulatory site within the leader sequence of
the tryptophan operon that controls this operon
by diminishing transcription is called:
• A.operator
• B.upregulator
• C.repressor
• D.transcriptor

• Which level of primary control in eukaryotic
gene activity involves processing early RNA
transcripts to mRNA and control of the rate at
which mRNA leaves the nucleus?
• A. transcriptional control
• B. translational control
• C. posttranscriptional control
• D. posttranslational control

• An enhancer site is
• A. part of an operon.
• B. found only in prokaryotes.
• C. located at a distance from the gene it
affects.
• D. an attachment site for RNA
polymerase.

Cell growth and carcinogenesis

Sample questions
• The event(s) which does not occur during
interphase, is/are
• A. Chromatin condenses
• B. Protein Synthesis
• C. Organelles replication
• D. DNA replication

The Cell
Cycle
• 2 major
phases
– Interphase
– Mitosis

• At the center of the cell cycle control
system is Cdk, a protein that
• A. is phosphorylated to become active
• B. binds to different cyclins
• C. is only active during mitosis
• D. manufactures growth factors

Sample questions
• An oncogene is
• A. a viral gene with no relation to the host cell's
genes.
• B. a mutated form of a proto-oncogene.
• C. a bacterial gene that causes cancer in the
host.
• D. a gene that turns off cellular reproduction.

Questions that have been reviewed

The complementary sequence in the
standard 5’ 3’ notation for GATCAA
is _______
• TTGATC

List at least 3 non-covalent
interactions in the biomolecules
• van der Waals
• Hydrogen bonds
• Ionic bonds
• Hydrophobic interactions

Explain the hydrophobic interactions
• Hydrophobic interactions minimize
interactions of non-polar components with
aqueous solvent.

How are proteins separated by
electrophoresis?
• The separation of proteins is done by
charge. pH is kept higher then the
isoelectric pH (pI). So, the proteins will
have negative charge and so the proteins
will move towards the positive electrode.

Explain the definition of domain of proteins.
• FFuunnddaammeennttaall ffuunnccttiioonnaall && tthhrreeee
ddiimmeennssiioonnaall ssttrruuccttuurraall uunniittss ooff pprrootteeiinnss..

What is the function of chaperones in
protein folding? List at least one role.
• AAssssiisstt ffoollddiinngg
• PPrrootteecctt aggregation
• SSoommee ttiimmeess kkeeeepp pprrootteeiinn uunnffoollddeedd uunnttiill
ssyynntthheessiiss iiss ccoommpplleettee..

Explain the difference between reversible denaturation and
irreversible denaturation of proteins.
• Some proteins can refold upon removal of
denaturant. Other can’t refold upon the removal
of denaturant.

Molecules contain both a positive and a
negative charged functional group is
called _____
• zwitterion

Hemoglobin is an allosteric protein that
can exist in two states: R (relaxed) and
T (taut). ____ state binds oxygen
tighter.
• R (relaxed)

The change in oxygen affinity with pH is known as
the Bohr effect. Hemoglobin oxygen affinity is ____
(increased/decreased) as the acidity increases.
• Reduced or decreased

Proteins that recognize and bind to a
particular antigen with very high
specificity belong to a group of serum
proteins called ______.
• Immunoglobulins or antibodies

What is the shape of the oxygen hemoglobin
dissociation curve?
How does the shape of the curve relate to
the cooperative binding of O2?
• Sigmoid or sigmoidal curve
• The small change of oxygen partial
pressure results in a greater change of
the hemoglobin binding affinity to oxygen.

How does the shape of oxygen–hemoglobin
dissociation curve influence loading of
oxygen at the lung and unloading of oxygen
at the tissue level?
• There are a high oxygen partial pressure
in the lung and a low oxygen partial
pressure in the other tissues. At high
oxygen pressure, the hemoglobin tends to
be saturated with oxygen while, at low
oxygen pressure hemoglobin tends to
unload all the oxygen molecules.

List at least 3 factors that influence the
binding of hemoglobin to oxygen.
• carbon dioxide or CO2
• pH or acidity
• Oxidative state of Fe in the heme group
• 2,3-DPG or 2,3-BPG
• Carbon monoxide or CO

_____ are long polymers of nucleotides.
• Nucleic acids

The maximal UV absorbance of nucleic
acids and proteins are at the wavelength of
___ nm and ___ nm, respectively.
• 260, 280

The sugar groups in the nucleic acids are
___ (D/L) ribose while the residues in the
protein are ___ (D/L) amino acids.
• D, L

Polymer of nucleotides linked in a
direction from ribose carbon ___ (3’/5’)
to carbon ___ (3’/5’) by ______bonds.
• 5’, 3’, phosphodiester

List at least 3 types of RNA molecules
in the biological system.
• ribosomal RNA or rRNA
• messenger RNA or mRNA
• transfer RNA or tRNA
• microRNA or miRNA
• small RNA or siRNA
• long non-coding RNA
• short non-coding RNA

Besides hydrophobic interactions, hydrogen
bonding, and electrostatic interactions,
nucleic acids have one more type of
noncovalent interaction that is called ____.
• Stacking interactions or base stacking
(interactions between stacked bases)

What is DNA melting temperature?
• the temperature at which a DNA double
helix dissociates into single strands

What is the purpose of using the polymerase
chain reaction (PCR) in diagnosis or research?
• to rapidly amplify sequences of DNA

In the nucleosome, DNA wrapped
around an octamer protein complex that
are called ____.
• histone

DNA binding proteins bind DNA in two ways:
sequence-specific binding and non-sequence
specific binding. Please list two example of non-sequence
specific binding proteins.
• Single-stranded nucleic acid binding
proteins (SSB)
• Exonucleases, RNase, or DNase
• RNA polymerases or DNA polymerases
• Topoisomerases

Define the enzyme active site.
• The active site of an enzyme represents
as the small region at which the substrate
(s) binds and participates in the catalysis

Feedback Inhibition is a type of allosteric
regulation for enzyme. When does feedback
inhibition occur?
• This occurs when an end-product of a
pathway accumulates as the metabolic
demand for it declines.

For every molecule of glucose that enters
glycolysis, there is an initial investment of 2
molecules of ____ before the subsequent
generation of ____ .
• ATP, ATP

What is the purpose of glucagon?
• It slows down glycolysis when blood sugar
is low and stimulates the formation of
more glucose.

An enzyme that catalyzes the
phosphorylation of a molecule using ATP is
called ____
• Kinase

Name two molecules that carries electrons
from glycolysis and Krebs Cycle to the
electron transport system.
• NADH and FADH2

Phosphofructokinase-1 (PFK-1) is an enzyme in glycolysis.
It’s activity is controlled by a complex allosteric regulation.
What is the function of AMP in the PFK-1 regulation?
• AMP allosterically activates PFK-1

There are three irreversible reactions in the
glycolysis. What are the corresponding
enzymes that catalyze those reactions?
• Hexokinase or Glucokinase
• Phosphofructokinase 1 or PFK-1
• Pyruvate Kinase

Hexokinase is allosterically inhibited by its product Glucose
6 phosphate. The hexokinase in the liver is called
glucokinase. However, glucokinase is not subject to product
inhibition by glucose-6-phosphate. What the benefit of this
characteristics of glucokinase?
• Liver will take up & phosphorylate glucose
even when liver glucose-6-phosphate
concentration is high.

During the Cori cycle, _____ is transported
to the liver to regenerate glucose which is
returned to muscle tissue.
• Lactic acid or lactate

Insulin is produced when blood glucose is
high. How does insulin regulate the
transcription of the glycolysis enzyme in liver,
glucokinase?
• Insulin activates of transcription of
Glucokinase in liver.

In the liver, the most important coordinating modulator is fructose 2,6-
bisphophate (F2,6BP). It is formed from F6P by the enzyme domain,
phosphofructokinase-2 (PFK-2), and broken down by the same enzyme,
but at a different domain called fructose 2,6-bisphosphatase (FBPase-
2). How does the balance of PFK-2 to FBPase-2 activity controlled by
glucagon?
• Glucagon causes the enzyme phosphorylation.
Phosphorylation of the enzyme results in the
inactivation of the phosphofructokinase-2 activity
and activation of the fructose-2,6-
bisphosphatase activity.

The last product of glycolysis is ____ while
the first reactant of Krebs cycle is ____.
• Pyruvate, Acetyl Co-A

Briefly explain the Cori cycle which is a
linked metabolic pathways.
• The glucose can enter the blood and be
carried to muscles.
• Lactic acid is produced by anaerobic
glycolysis in the muscles
• The lactic acid is sent in the blood to the
liver which can convert it back to glucose
through gluconeogenesis.

What is epinephrine’s role in glycogen
and glucose metabolism?
• Epinephrine markedly stimulates glycogen
breakdown and glycolysis.

Palmitic acid, CH3(CH2)14COOH, can
maximally yield ____ acetyl-CoAs
through ____ cycles of beta-oxidation.
• Eight, seven

Why can acetone be detected on
breath of diabetic patients?
• Acetone breath in diabetics is caused by an
excess production of ketone bodies.
• Glucose is abundant in blood, but uptake by
cells in muscle, liver, and adipose cells is low.
Cells, metabolically starved, turn to
gluconeogenesis and fat/protein catabolism
• However, due to excess gluconeogenesis,
oxaloacetate is low, so acetyl-CoA from
fat/protein catabolism does not go to TCA, but
rather to ketone body production.

High cholesterol diet leads to ____
(promotion/repression) of LDL receptor synthesis.
• repression

Chylomicrons are vesicles found in the blood and lymphatic
fluid where they serve to transport lipid from the intestine to
the liver and to adipose tissue. Of what are the chylomicrons
composed? List at least 3 components.
• Triglycerides
• Cholesterols
• lipoproteins
• phospholipids
• Cholesteryl ester

What is the effect of epinephrine and
glucagon on triglyceride metabolism?
• Epinephrine and glucagon trigger the
mobilization of stored triglycerides

What is oxidative phosphorylation?
• Answer1: Oxidative phosphorylation
transfers energy from NADH to ATP. (via
chemiosmosis)
• Answer2: Oxidative phosphorylation is the
process of converting this high redox
potential into energy-rich ATP molecules.

Oxidative phosphorylation is accomplished
via two separate systems in the
mitochondrion. What are those two systems?
• Electron transport chain system and ATP
synthesis system.

ATP synthesis is driven by proton motive
force. What are the two types of gradient
associated with proton motive force?
• a proton gradient or pH gradient
• a electrical gradient or ion gradient

Metabolism of amino acids differs, but all of
them require the removal of amino groups.
What are the two types of reactions to
remove amino groups?
• Transamination
• Deamination

Disposal of ammonia from amino acid metabolism
as _____ in most tissues especially in the brain
and kidneys, as _____ in the liver, and as _____
in the skeletal muscles.
• Glutamine, urea, alanine

Based on the catabolic fates of carbon
skeleton of amino acids, the amino
acids can be classified as ____ or
_____.
• Glucogenic, ketogenic

Dietary nucleotides _____ (do/do not)
contribute energy as an energy source
material and _____ (are/are not)
incorporated into RNA or DNA.
• Do not, are not

The purine nucleotides are synthesized via
two pathways in the body. One is ____
synthesis pathway while the other is ____
pathway.
• De novo, salvage

The purine synthesis is _____ by PRPP,
_____ by IMP, _____ by AMP, and _____by
GMP. Fill the blank with activated or
inhibited.
• Activated, Inhibited,
Inhibited, Inhibited,

What are the carbohydrate and fat
metabolic events occurred in liver
during fasting?
• The liver first starts glycogen degradation,
then gluconeogenesis to maintain blood
glucose levels.
• The fatty acid oxidation and ketone body
production are increased.

Insulin promotes the translocation of
______ to the plasma membrane.
• GLUT or glucose transporter

Why do we say that DNA replication is
semiconservative?
• The new strands composed of one original
strand and one daughter strand

DNA polymerases cannot initiate synthesis of a
polynucleotide; they can only add nucleotides to
the 3’ end. Therefore, a short _____ is required to
initiate nucleotide synthesis.
• RNA primer

Eukaryotic chromosomal DNA molecules have
special nucleotide sequences at their ends called
______.
• telomeres

Why is DNA replication semi-discontinuous?
• DNA strands are antiparallel. And,
replication process obeys the principle that
DNA is synthesized from the 5´ end to the
3´end.
• Leading strand synthesized continuously
while lagging strand synthesized
discontinuously

List at least 3 differences between
replication and transcription.
replication transcription
template double strands single strand
substrate dNTP NTP
primer yes no
Enzyme DNA polymerase RNA polymerase
product dsDNA ssRNA
base pair A-T, G-C A-U, T-A, G-C
The whole genome of DNA needs to be replicated, but only small
portion of genome is transcribed

During transcription, one of the DNA strands
called ______ strand is the strand from which
the RNA is actually transcribed. The other
strand called _____ strand is the strand whose
base sequence specifies the amino acid
sequence of the encoded protein.
• Template, coding

What is asymmetric transcription?
• Only the template strand is used for the transcription, but
the coding strand is not.
• The transcription direction on different strands is
opposite.
5'
3'
3'
5'

The mRNA start codon is ___ in
most cases.
• AUG

Deoxyribonucleotides are formed from
their corresponding _____.
• ribonucleotides

Explain mRNA splicing
• During splicing, introns are removed from
the strand, and the exons that remain are
assembled into a finished strand of mRNA
that is ready for translation.

What is the consequence of
frameshift mutation?
• Frameshift mutations result in all
subsequent reading frames (codons)
being shifted by one or two nucleotides.
These shifted frames will code for different
amino acids than before, and will result in
the creation of a malfunctioning protein.

The GUU  GUA transition still codes for
Val and it therefore called to be ______
mutation.
• nonsense

The insertion or deletion of a nucleotide
into a gene results in a _____ mutation.
• frameshift

An incoming aminoacyl-tRNA enters
the ribosome at the ___ site.
• A

____ are synthesized as inactive precursors
that require proteolysis for activation.
• zymogen or proenzyme

In the operon system, tryptophan acts
as a ____ by binding the trp repressor.
• Co-repressor

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