Biochemistry Flashcards
Glucose and fructose are examples of
double sugars
disaccharides
single sugars
polysaccharides
single sugars
(CH2O)n is the molecular formula for
which type of macromolecules?
Proteins
Lipids
Carbohydrates
Nucleic Acid
Carbohydrates
Which of the following is NOT a
polysaccharide?
Glycogen
Starch
Sucrose
Cellulose
Sucrose
What are used in animals as a source of
quick energy that can be stored in the
liver and muscles ？
Proteins
Nucleic acids
Carbohydrates
Lipids
Carbohydrates
Sugars, starches, and cellulose belong to which major class of biological molecules?
Nucleic acids
carbohydrates
lipids
polypeptides
carbohydrates
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?
carbohydrates
calories
starches
cellulose
starches
Which macromolecule does not
dissolve in water?
proteins
lipids
carbohydrates
nucleic acids
lipids
Monosaccharides have yellow appearance and are soluble in water. True or False?
True, they are yellow and soluble in water.
False, they are yellow and are insoluble in
water
False, they are colorless and are soluble in
water
False, they are colorless and insoluble in
water.
False, they are colorless and are soluble in water
What are the monomers of lipids?
Amino acids
Simple sugars
Fatty acids and glycerol
Nucleic acids
Fatty acids and glycerol
Lipids are used by the body to perform all
of the following functions EXCEPT:
membrane structural material.
enzyme action.
insulation.
a rich energy source.
enzyme action.
What type of organic substances are fats?
nucleic acid
carbohydrate
protein
lipids
lipids
Fats that have fatty acids with only single
covalent bonds in their carbon skeletons
are
saturated
unsaturated
found in plants instead of animals
liquid at room temperature
saturated
Which has the higher melting point: (a) a
triglyceride containing only lauric acid and
glycerol or (b) a triglyceride containing
only stearic acid and glycerol?
(a)
(b)
Both have equal melting points
None of the above
(b)
Which of the following is a polymer?
nucleic acid
fatty acid
Amino acid
Glycerol
nucleic acid
This biological macromolecule is
responsible for controlling the activity of the
cell, and it stores and transports genetic
information.
Carbohydrate
Nucleic acid
Water
Glucose
Nucleic acid
What are described as the “building
blocks of Protein”?
Fiber
Lipids
Amino Acids
Nutrients
Amino Acids
Proteins are ____ made of ____ amino acid .
monomers; polymers
polymers; polypeptides
polymers; monomers
monomers; molecules
polymers; monomers
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:
Alpha-helix
Beta-sheet
Beta-turn
Quaternary
Alpha-helix
The isoelectric point of an amino acid is defined as the pH
where the molecule carries no electric charge
where the carboxyl group is uncharged
where the amino group is uncharged
of maximum electrolytic mobility
where the molecule carries no electric charge
When the amino acid alanine (R-group is CH3) is added to a solution with a pH of 7.3, alanine becomes
a cation
nonpolar
a zwitterions
an anion
Isoelectric point of alanine is 6.00
an anion
The term “SALTING IN” refers to?
Changes in an amino acid’s isoelectric
point.
Increasing the solubility of a protein in
solution by adding ions.
The use of a liquid bridge in an
electrochemical cell.
The ionization of a strong acid.
Increasing the solubility of a protein in solution by adding ions.
The local spatial arrangement of a
polypeptide’s backbone atoms without regard
to the conformation of its side chains can be
called as
Primary structure
Secondary structure
Tertiary structure
Quaternary structure
Secondary structure
Which of the following amino acids are
more likely to be found in a protein’s
interior away from aqueous solvent
molecules?
Val, Leu, Ile, Met, and Phe
Ser, Thr, Asn, Gln, and Tyr
Arg, His, Lys, Asp, and Glu
All of the above.
Val, Leu, Ile, Met, and Phe
Which of the following is (are) true of β- turns in proteins?
It is a 180º turn of four amino acids.
Glycine and proline are frequently found there.
Are used as connecting turns of -helix
All of the above.
All of the above.
The primary stabilizing force of protein secondary structure is:
Ionic bonds.
Covalent bonds.
Van der Waals forces.
Hydrogen bonds
Hydrogen bonds
Two types of β-pleated sheets can be
called:
parallel and antiparallel
left-handed and right-handed.
Φ and Ψ
α and β
parallel and antiparallel
Which of the following is NOT a characteristic
of a globular protein?
Polypeptide chain in extended, long sheets
Polypeptide chains are folded in a spherical shape.
Contains several types of secondary structure
Typical for regulatory proteins
Polypeptide chain in extended, long sheets
The alpha helix found in myoglobin can
best be described as
Primary structure
Secondary structure
Tertiary structure
Motif structure
Secondary structure
Some parts of a protein that have a specific
chemical structure and function are called
protein
chemicals
domains
subunits
enzymes
domains
One of the following is NOT usually a
force that helps to hold the monomer
units of a quaternary protein together?
Peptide bonds
Disulfide bonds
Salt bonds
Hydrophobic interactions
Peptide bonds
Which of the following is a secondary
structure breaker/alpha helix
terminator?
Pro
Glu, Leu
Phe
Cys, Ser
Pro
If a person breathes into a paper bag, you would expect their blood CO2 to
decrease and their blood pH to increase
decrease and their blood pH to decrease
increase and their blood pH to increase
increase and their blood pH to decrease
increase and their blood pH to decrease
The quaternary structure of a protein is the sequence of amino acids in the
polypeptide
the coiling or folding of the polypeptide
the intertwining of two or more polypeptides
the 3-dimensional appearance of the polypeptide
the intertwining of two or more polypeptides
The action of disrupting the threedimensional shape of a protein is
termed
dehydration
denaturation
deamination
hydrolysis
denaturation
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 amino acid found in protein
structure
Arginine
Proline
Histidine
Lysin
Arginine
The bonds in protein structure that are not broken on denaturation.
Hydrogen bonds
Peptide bonds
lonic bond
Disulfide bonds
Peptide bonds
What is the product of the oxidation of
dopamine
R-Epinephrine
Phenylalanine
Tyrosine
Dihydroxyphenylalanine
R-Epinephrine
Which of the following is not considered a pyrimidine?
C
T
U
G
G
PYCUT - Pyramidine ~ Cytosine Uracil Thymine
PURGA - Purine ~ Adenine Guanine
What type of sugar is found in the nucleotides of DNA?
deoxyribose
ribose
glucose
none of the above
deoxyribose
What is the role of hydrogen bonds in
the structure if DNA?
to code for proteins
to synthesize proteins
to separate the strands
to connect the base pairs
to connect the base pairs
Nucleoside is a pyrimidine or purine base
covalently bonded to a sugar
ionically bonded to a sugar
hydrogen bonded to a sugar
none of the above
covalently bonded to a sugar
The sugar in RNA is ____ , the sugar in DNA is ____
deoxyribose, ribose
ribose, deoxyribose
ribose, phosphate
ribose, uracil
ribose, deoxyribose
In gel electrophoresis, what fragments will move most quickly through a gel?
Large fragments
Small fragments
Large genome
None of these
Small fragments
Nucleotide bases and aromatic amino acids absorb light respectively at
280 and 260 nm
260 and 280 nm
270 and 280 nm
260 and 270 nm
260 and 280 nm
Which of the following is found
on RNA but not DNA?
Uracil
Deoxyribose
Phosphate
Adenine
Uracil
DNA - CAGT = Cytosine, Adenine, Guanine, Thymine
RNA - CAGU = Cytosine, Adenine, Guanine, Uracil
Which is true about the pairing of bases in the DNA molecule?
purines always pair with pyrimidines
a single ring base pairs with another single ring base
a double ring base pairs with another double ring base
purines pair with purines and pyrimidines with pyrimidines
purines always pair 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:
999
630
330
111
110
111
start: AUG - methionine
AGC - serine
AGG - arginine
GUC - valine
(336 - 3) (1/3) = 111
What is the function of enzymes within living systems?
structural elements
neurotransmitters
catalysts
hormones
catalysts
Enzymes have names that
always end in -ase
always end in -in
can end either in -in or -ase
can end in either -in or -ogen
can end either in -in or -ase
The protein portion of a conjugated enzyme is called a(n)
apoenzyme.
coenzyme.
holoenzyme.
cofactor.
apoenzyme.
apoenzyme - protein portion
Which of the following could be a component of a conjugated enzyme?
coenzyme
cofactor
apoenzyme
more than one correct response
no correct response
more than one correct response
Enzyme cofactors that bind covalently at the active site of an enzyme are referred to as .
cosubstrates.
prosthetic groups.
apoenzymes.
vitamins
prosthetic groups.
Which of the following statements concerning the effect of temperature
change on an enzyme-catalyzed reaction is correct?
An increase in temperature can stop the reaction by
denaturing the enzyme.
An increase in temperature can increase the reaction rate
by increasing the speed at which molecules move.
An increase in temperature to the optimum temperature
maximizes reaction rate.
more than one correct response
no correct response
more than one correct response
A catalyst can promote product formation during a chemical reaction by
lowering the activation energy barrier.
stabilizing the transition state.
positioning reactants in the correct orientation.
bringing reactants together.
all of the above
all of the above
Which of the following is characteristic of an enzyme catalyst?
It positions reactants in the correct orientation.
It lowers the activation energy barrier.
It binds the transition state tighter than the substrate.
all of the above
all of the above
An enzyme active site is the location in the enzyme where
protein side groups are brought together by bending and folding to form a site for interactions with substrates
the catalyst interactions with the enzyme
catalyst molecules are generated
the substrate creates the catalyst molecules
protein side groups are brought together by bending and folding to form a site for interactions with substrates
An enzyme active site is the location in an enzyme where substrate
molecules
are generated.
become catalysts.
undergo change.
none of these
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:
The concentration of C is increased one-hundred fold
The concentration of A is increased one-hundred fold
The concentration of B is lowered one-hundred fold
The concentration of both A and D are increased onehundred fo
The concentration of A is increased one-hundred fold
Which of the following statements about enzymes or their function is true?
Enzymes do not alter the overall change in free energy for a reaction
Enzymes are proteins whose three-dimensional form is key to their function
Enzymes speed up reactions by lowering activation energy
All of the above
All of the above
What is the optimal temperature range
for the majority of enzymes?
40-55 ℃
35-40 ℃
25-30 ℃
15-20 ℃
35-40 ℃
An allosteric activator
increases the binding affinity
decreases the binding affinity
stabilizes the R state of the protein
both (a) and (c)
both (a) and (c)
Reactants of an enzyme-catalyzed reaction are known as
products
substrates
proteins
complex
substrates
The location on an enzyme where
binding occurs is known as the
action point
enzyme
binding location
active site
active site
Enzymes catalyze reactions by
Increasing the free energy of the system so that the change in free energy is positive
Increasing the free energy of the substrate so that it isgreater than the free energy of the product
Changing the equilibrium constant for the reaction
Decreasing the free energy of activation
Decreasing the free energy of activation
An apoenzyme
Includes non-protein compounds such as metal ions
Consists of complex organic structures which may be classified as activation-transfer coenzymes or oxidationreduction coenzymes
Is the protein portion of the enzyme without the cofactors
None of the above
Is the protein portion of the enzyme without the cofactors
apoenzyme - protein portion
NAD+, FAD, and FMN are all cofactors for:
Oxidoreductases
Transferases
Hydrolases
Ligases
Oxidoreductases
At the end of a chemical reaction
an enzyme’s structure is altered
an enzyme is detached from the product, has its original structure, and can catalyzemore chemical reactions
the enzyme loses its ablity to catallyze other chemical reactions
the enzyme remains attached to the products
an enzyme is detached from the product, has its original structure, and can catalyze more chemical reactions
The rate of a second order reaction depends on the concentration of ____.
one substrate
two substrates
three substrates
none of the above
two substrates
Which of the following statements about allosteric enzymes is CORRECT?
The binding of substrate to any active site affects the other active sites
The plot of initial velocity vs. substrate concentration is a straight line
The Keq of the reaction is increased when allosteric activator is bound
The enzymes contains only one polypeptide chain
The binding of substrate to any active site
affects the other active sites
Which of the following kinetic parameters best describes how well suited a specific compound functions as a substrate for a particular enzyme?
Km
Vmax
kcat
kcat/Km
kcat/Km
Km - substrate specificity; substrate binding
kcat - turnover number
kcat/Km - catalytic efficiency
The rate-determining step of Michaelis Menten kinetics is
the complex formation step
the complex dissociation step to produce product
the product formation step
Both (a)and(c)
the complex dissociation step to produce product
A competitive inhibitor of an enzyme works by
fitting into the enzyme’s active site
fitting into the allosteric site of the enzyme
attaching itself to the substrate, thereby preventing the enzyme from making contact with substrate
increasing the activation energy of the enzymecatalyzed reaction
fitting into the enzyme’s active site
If an enzyme is described by the Michaelis-Menten equation, a competitive inhibitor will:
decrease the Km and decrease the Vmax
decrease the Km, but not the Vmax
always just change the Vmax
increase the Km but not change the Vmax
increase the Km but not change the Vmax
The most likely effect of a non-competitive inhibitor on an Michaelis-Menten enzyme is to
Increase the Vmax
Decrease the Vmax
Increase both the Vmax and the Km
Decrease both the Vmax and the Km
Decrease the Vmax
Which of the following binds to an enzyme at its active site?
irreversible inhibitor
reversible competitive inhibitor
reversible noncompetitive inhibitor
more than one correct response
no correct response
reversible competitive inhibitor
An uncompetitive inhibitor binds to ____.
E
ES
P
a and b
ES
A reversible inhibitor that can bind to either E alone or the ES complex is referred to as a .
competitive inhibitor.
non-competitive inhibitor.
uncompetitive inhibitor.
suicide inhibitor.
irreversible inhibitor.
non-competitive inhibitor
A competitive inhibitor of an enzyme is usually
a highly reactive compound
a metal ion such as Hg2+or Pb2+
structurally similar to the substrate.
water insoluble
structurally similar to the substrate.
The enzyme inhibition can occur by
reversible inhibitors
irreversible inhibitors
Both (a) and (b)
None of these
Both (a) and (b)
In a Lineweaver-Burk Plot, competitive inhibitor shows which of the following effect?
It moves the entire curve to right
It moves the entire curve to left
It changes the x-intercept
It has no effect on the slope
It changes the x-intercept
Non-competitive inhibitor of an enzyme catalyzed reaction
decreases Vmax
binds to ES
both (a) and (b)
can actually increase reaction velocity in rare
cases
both (a) and (b)
A classical uncompetitive inhibitor is a compound that binds
reversibly to the enzyme substrate complex yielding an inactive ESI complex
irreversibly to the enzyme substrate complex yielding an inactive ESI complex
reversibly to the enzyme substrate complex yielding an active ESI complex
irreversibly to the enzyme substrate complex yielding an active ESI complex
reversibly to the enzyme substrate complex yielding an inactive ESI complex
Allosteric modulators seldom resemble the substrate or product of the enzyme. What does this observation show?
Modulators likely bind at a site other than the active site.
Modulators always act as activators.
Modulators bind non-covalently to the enzyme.
The enzyme catalyzes more than one reaction
Modulators likely bind at a site other than the active site.
Some enzymatic regulation is allosteric. In such cases,
which of the following would usually be found?
cooperativity
feedback inhibition
both activating and inhibitory activity
an enzyme with more than one subunit
the need for cofactors
an enzyme with more than one subunit
How many moles of lactate are produced from 3 moles of glucose
2
4
6
8
6
Glycolytic pathway regulation involves
allosteric stimulation by ADP
allosteric inhibition by ATP
feedback, or product, inhibition by ATP
all of the above
feedback, or product, inhibition by ATP
Why does the glycolytic pathway continue in the direction of glucose catabolism?
There are essentially three irreversible reactions that act as the driving force for the pathway
High levels of ATP keep the pathway going in a forwarddirection
The enzymes of glycolysis only function in one direction
Glycolysis occurs in either direction
There are essentially three irreversible reactions that act as the driving force for the pathway
The released energy obtained by oxidation of glucose is stored as a concentration gradient across a membrane
ADP
ATP
NAD+
ATP
For every one molecule of sugar glucose which is oxidized
molecule of pyruvic acid are produced.
1
2
3
4
2
The enzymes of glycolysis in a eukaryotic cell are located in the
intermembrane space
plasma membrane
cytosol
mitochondrial matrix
cytosol
Which of the following is not true of glycolysis?
ADP is phosphorylated to ATP via substrate level phosphorylation
The pathway does not require oxygen
The pathway oxidizes two moles of NADH to NAD+for each mole of glucose that enters
The pathway requires two moles of ATP to get startedcatabolizing each mole of glucose
The pathway oxidizes two moles of NADH to NAD+for each mole of glucose that enters
ATP is from which general category of molecules?
Polysaccharides
Proteins
Nucleotides
Amino acids
Nucleotides
Which of the following regulates glycolysis steps?
Phosphofructokinase
Hexose kinase
Pyruvate kinase
All of these
All of these
Which of the following is not a mechanism for altering the flux of metabolites through the rate-determining step of a pathway?
Allosteric control of the enzyme activity
Block active sites
Genetic control of the enzyme concentration
Covalent modification of the enzyme
Block active sites
Phosphofructokinase, the major flux-controlling enzyme of glycolysis is allosterically inhibited and activated respectively by
ATP and PEP
AMP and Pi
ATP and ADP
Citrate and ATP
ATP and ADP
Where does glycolysis occur?
inner membrane of mitochondria
matrix of mitochondria
stroma of chloroplast
cytoplasm
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?
oxygen
ATP
lactate
carbon dioxide
lactate
There are four enzymes of gluconeogenesis that circumvent the irreversible steps in glycolysis. When starting with the substrate pyruvate or lactate they are
Hexokinase, phosphofructokinase-1,
phosphofructokinase-2 and pyruvate kinase
Pyruvate carboxylase, phosphoenolpyruvate
carboxykinase, fructose-1,6-bisphosphatase, and glucose-6-phosphatase
Glycerol kinase, glycerol-3-phosphate
dehydrogenase, fructose-2,6-bisphosphatase, and glucose-6-phosphatase
Amino transferase, phosphoenolpyruvate
carboxykinase, fructose-2,6-bisphosphatase, and glucose-6-phosphatase
Pyruvate carboxylase, phosphoenolpyruvate
carboxykinase, fructose-1,6-bisphosphatase, and glucose-6-phosphatase
The enzymes that remove phosphate groups during the process of gluconeogenesis and circumvent two of the three irreversible reactions of glycolysis are
Pyruvate kinase and glycerol kinase
Phosphoenolpyruvate carboxykinase and glycerol kinase
3-Phosphoglycerate kinase and fructose-1,6-bisphosphatase
Fructose-1,6-bisphosphatase and glucose-6-phosphatase
Fructose-1,6-bisphosphatase and glucose-6-phosphatase
The most important control step in gluconeogenesis is fructose-1,6- bisphosphatase. All of the following statements are true EXCEPT
Fructose-1,6-bisphosphatase converts fructose-2,6-bisphosphate to fructose-6-phosphate
During times when insulin is high, fructose-1,6-bisphosphatase is inhibited by fructose-2,6-bisphosphate
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
Glycolysis or gluconeogenesis cannot be active at the same time. If they were is would be a futile cycle
Fructose-1,6-bisphosphatase converts fructose-2,6-bisphosphate to fructose-6-phosphate
In the liver, glucagon will activate
Glycolysis and glycogen synthesis
Gluconeogenesis and glycogenolysis
Gluconeogenesis and glycogen synthase
Gluconeogenesis and glycogen synthesis
Gluconeogenesis and glycogenolysis
Which of the following statements about hormonal levels during different
states is true?
During the time you are eating a high carbohydrate mixed meal, the insulin to glucagon ratio will decrease
When passing from the fed to fasting state, insulin and glucagon usually decrease
When playing basketball, epinephrine is usually low and insulin is high
After running for 20 miles, epinephrine and glucagon are high and insulin is low
After running for 20 miles, epinephrine and glucagon are high and insulin is low
All of the following will result in activation ofglycogen phosphorylase in skeletal muscle EXCEPT
Increased concentrations of AMP from contraction of muscle
Increased epinephrine and cAMP
Increased cytosolic [Ca++]
Increased protein phosphatase
Increased activity of glycogen phosphorylase kinase
Increased protein phosphatase
A biological redox reaction always involves
an oxidizing agent
a gain of electrons
a reducing agent
all of these
all of these
Coenzyme Q is involved in electron transport as
directly to O2
a water-soluble electron donor
covalently attached cytochrome cofactor
a lipid-soluble electron carrier
a lipid-soluble electron carrier
FAD is reduced to FADH2 during
electron transport phosphorylation
lactate fermentation
Krebs cycle
glycolysis
Krebs cycle
During glycolysis, electrons removed from glucose are passed to
FAD
NAD+
acetyl CoA
pyruvic acid
NAD+
Almost all of the oxygen (O2) one consumes in breathing is converted to:
acetyl-CoA.
carbon dioxide (CO2).
carbon monoxide and then to carbon dioxide.
water.
water
The carbon dioxide is primary a product of
Krebs cycle
glycolysis
electron transport phosphorylation.
lactate fermentation.
Krebs cycle
Cellular respiration takes place mostly in:
chloroplasts
ribosomes
nucleus
mitochondria
mitochondria
Which of the following is not present
during the TCA cycle?
NADH
O2
CO2
ATP
O2
Which of the following is a list of the stages in the correct order?
pyruvate oxidation, glyocolysis, the citric acid cycle, and oxidative phosphorylation
oxidative phosphorylation, glyocolysis, the citric acid cycle, and pyruvate oxidation
glycolysis, pyruvate oxidation, the citric acid cycle, and oxidative phosphorylation
glycolysis, the citric acid cycle, pyruvate oxidation, and oxidative phosphorylation
glycolysis, pyruvate oxidation, the citric acid cycle, and oxidative phosphorylation
What are the products of the citric acid cycle?
NADH, ATP, FADH2, and CO2
O2, ADP, 1 FAD, and NAD+
Glucose, ATP, O2, and NADH
heat, H2O, NADH, and pyruvate
NADH, ATP, FADH2, and CO2
Which of the following is NOT a way of producing ATP in humans?
Krebs Cycle
Alcohol Fermentation
Lactic Acid Fermentation
Glycolysis
Alcohol Fermentation
Which of the following is an aerobic product of pyruvate catabolic metabolism?
lactate
ethanol
acetyl CoA
glucose
ethanol
The TCA cycle:
Is found in the cytosol
Is controlled by the ADP/ATP ratio and the NADH concentration
Is also called the Cori cycle
Produces most of the water made in humans
Is controlled by the ADP/ATP ratio and the NADH concentration
The Krebs Cycle begins when pyruvic acid produced by glycolsis enters the
cytosol
air
mitochondrion
nuclear
mitochondrion
In aerobic organisms growing in the presence of oxygen, the NADH produced by glycolysis ultimately donates its high-energy electrons to
electron transport chains in the mitochondria
ATP
pyruvate
glucose
electron transport chains in the mitochondria
Cellular respiration takes place mostly
in:
chloroplasts
ribosomes
nucleus
mitochondria
mitochondria
The main purpose of the electron transport chain is to:
Use high energy electrons from other cycles to convert ADP into ATP
Maintain a stable balance of high energy electrons
Constantly distribute electrons throughout the cell
Tell the cell when glycolysis should stop or start
Use high energy electrons from other cycles to convert ADP into ATP
Oxidative phosphorylation:
Is anaerobic
Requires AMP
Requires the electron transport system
Is not dependent upon development of a proton gradient
Requires the electron transport system
Where are the proteins of the electron transport chain located?
cytosol
mitochondrial outer membrane
mitochondrial inner membrane
mitochondrial matrix
mitochondrial inner membrane
The ATP synthase responsible for most of the ATP synthesis in the body is located:
On the outer side of the outer mitochondria membrane
On the inner side of the outer mitochondria membrane
On the outer side of the inner mitochondria membrane
On the inner side of the inner mitochondria membrane
On the inner side of the inner mitochondria membrane
In the electron transport chain, the final
electron acceptor is
oxygen
a molecule of carbon dioxide
a molecule of water
ADP
oxygen
Anemia, hemorrhage, and chronic obstructive pulmonary disease can all cause metabolic acidosis. The best explanation is that the lack of oxygen causes
a decrease in insulin that, in turn, increases anaerobic glycolysis in the brain
a decrease in oxidative phosphorylation so the cells have to rely upon anaerobic glycolysis
a decrease in the removal of CO2 from the blood. The resulting decrease in pH causes an increase in glycolysis in most cells
an increase in glycolysis in red blood cells
a decrease in the removal of CO2 from the blood. The resulting decrease in pH causes an increase in glycolysis in most cells
Hydrolysis of a triglyceride produces
many amino acids
different types of nucleotides
fatty acids and glycerol
monosaccharides
fatty acids and glycerol
The site of amino acid catabolism is the:
Stomach
Small intestine
Large intestine
Liver
Liver
The first step in the catabolism of most amino acids is
Removal of carboxylate groups
Enzymatic hydrolysis of peptide bonds
Removal of the amino group
Zymogen cleavage
Removal of the amino group
Which of the following is true of urea?
more toxic to human cells than ammonia
the primary nitrogenous waste products of humans.
insoluble in water
the primary nitrogenous waste product of
most aquatic invertebrates
the primary nitrogenous waste products of humans.
A glucogenic amino acid is one which is degraded to
keto-sugars
either acetyl CoA or acetoacetyl CoA
pyruvate or citric acid cycle intermediates
none of the above
pyruvate or citric acid cycle intermediates
Transamination is the process where
carboxyl group is transferred from amino
acid
α-amino group is removed from the amino
acid
polymerization of amino acid takes place
none of the above
α-amino group is removed from the amino
acid
Transamination is the transfer of an amino
acid to a carboxylic acid plus ammonia
group from an amino acid to a keto acid
acid to a keto acid plus ammonia
group from an amino acid to a carboxylic
acid
group from an amino acid to a keto acid
In inherited deficiency of hypoxanthine guanine phosphoribosyl transferase
De novo synthesis of purine nucleotides is decreased
Salvage of purines is decreased
Salvage of purines is increased
Synthesis of uric acid is decreased
Salvage of purines is increased
Which of the following is a required substrate for purine biosynthesis ?
5- methyl thymidine
Ribose phosphate
PRPP
5-Fluoro uracil
PRPP
The conversion of Inosine mono phosphate
To Adenosine mono phosphate (AMP) is inhibited by Guanosine mono phosphate (GMP)
To AMP requires uridine mono phosphate
(UMP)
To GMP requires GMP kinase
To GMP requires Glutamine
To GMP requires Glutamine
Both strands of DNA serve as templates concurrently in
replication
excision repair
mismatch repair
none of these
replication
Proofreading activity to maintain the fidelity of
DNA synthesis
occurs after the synthesis has been completed
is a function of the 3’-5’ exonuclease activity of the DNA polymerases
requires the presence of an enzyme separate from the DNA polymerases
occurs in prokaryotes but not eukaryotes
is a function of the 3’-5’ exonuclease activity of the DNA polymerases
Which of the following repairs nicked DNA by forming a phosphodiester bond between adjacent nucleotides?
Helicase
DNA gyrase
Topoisomerases
DNA ligase
DNA ligase
DNA ligase repairs nicked DNA
The replication of chromosomes by eukaryotes occurs in a relatively short period of time because
the eukaryotes have more amount of DNA for replication
the eukaryotic replication machinery is 1000 times faster than the prokaryotes
each chromosome contains multiple replicons
eukaryotic DNA is always single stranded
each chromosome contains multiple replicons
During which of the following process a new copy of a DNA molecule is precisely synthesized?
Trasformation
Transcription
Translation
Replication
Replication
Which of the following enzyme adds complementary bases during replication?
Helicase
Synthesase
Replicase
Polymerase
Polymerase
Which of the following enzymes unwind short stretches of DNA helix immediately ahead of a replication fork?
DNA polymerases
Helicases
Single-stranded binding proteins
Topoisomerases
Helicases
Which DNA polymerase removes RNA primers in DNA synthesis?
Polymerase I
Polymerase II
Polymerase III
none of these
Polymerase I
Enzyme, responsible for proofreading base pairing is
DNA polymerase
Telomerase
Primase
DNA lig
DNA polymerase
PP proofreading polymerase
DNA helicase is used to
unwind the double helix
interact the double helix closely
break a phosphodiester bond in DNA strand
none of the above
unwind the double helix
The synthesis of DNA by DNA polymerase occurs in the
3’ to 5’ direction
5’ to 5’ direction
5’ to 3’ direction
3’ to 3’ direction
5’ to 3’ direction
The 5’ and 3’ numbers are related to the
length of the DNA strand
carbon number in sugar
the number of phosphates
the base pair rule
carbon number in sugar
What is the main damaging effect of UV radiation on DNA?
Depurination
Formation of thymine dimers
Single strand break
Dehydration
Formation of thymine dimers
Which of the following enzyme is used for synthesis of RNA under the direction of DNA?
RNA polymerase
DNA ligase
DNA polymerase
RNA ligase
RNA polymerase
Which of the following is a product of
transcription?
mRNA
tRNA
rRNA
all of these
all of these
Recognition/binding site of RNA polymerase is called
receptor
promoter
facilitator
terminator
promoter
An mRNA transcript of a gene contains
a start codon
a stop codon
a terminator
all of these
all of these
Where in the cell is the DNA transcribed into mRNA?
Cytoplasm
Nucleus
Golgi
Cell cytoskeleton
Nucleus
Since the two strands of the DNA molecule are complementary, for any given gene:
The RNA polymerase can bind to either strand.
Only one strand actually carries the genetic code for a particular gene.
Each gene possesses an exact replica so that no mutation occurs.
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.
Only one strand actually carries the genetic code for a particular gene.
The site of protein synthesis is
Ribosome
Nucleus
Endoplasmic reticulum
Chromosome
Ribosome
The structure in a bacterium that indicates an active site for protein synthesis is
a chromosome.
a cell membrane,
a flagellum.
a polysome.
a polysome
Which of the following is not necessary for protein synthesis to occur, once transcription is completed?
tRNA
Ribosomes
mRNA
DNA
DNA
During the process of translation:
the peptide is ‘passed’ from the tRNA in the P-site to the tRNA in the A-site.
incoming tRNAs must first bind to the E-site.
initiation begins with the binding of the ribosomal SSU to the poly-A tail of the mRNA.
the mRNA is translated by one ribosome at a time
the peptide is ‘passed’ from the tRNA in the P-site to the tRNA in the A-site.
The nucleolus of the nucleus is the site
where:
RNA processing occurs
rRNA is transcribed and ribosomal subunits are assembled
tRNA are charged with amino acids
mRNA is translated into protein
rRNA is transcribed and ribosomal subunits are assembled
The ribosomes are composed of
proteins
RNA
both (a) and (b)
lipids
both (a) and (b)
Which is required for protein synthesis?
tRNA
mRNA
rRNA
All of these
All of these
In the genetic code there are:
more tRNAs than codons.
more codons than amino acids.
more nucleotides than codons.
the same number of codons and amino acids
more codons than amino acids.
the anticodon of tRNA
binds to rRNA
binds to an amino acid
binds to the Shine Dalgarno sequence
binds to an mRNA codon
binds to an mRNA codon
Initiation of eukaryotic translation begins when the:
large and small subunits link together, then bind tothe mRNA.
ribosomal small subunit holding an initiator tRNA binds to the 5’ end of mRNA.
ribosome binds to of the start codon and an initiator tRNA enters the ribosome.
initiator tRNA binds to the start codon, followed by binding of the ribosome large subunit.
ribosomal small subunit holding an initiator tRNA binds to the 5’ end of mRNA
On the ribosome, mRNA binds
between the subunits
to the large subunit
to the small subunit
none of these
to the small subunit
Ribosomes select the correct tRNAs
based on the aminoacyl group
solely on the basis of their anticodons
depending on their abundance in the cytosol
with the least abundant anticodons
solely on the basis of their anticodons
Which of the following amino acid starts all proteins synthesis?
Glycine
Proline
Thymine
Methionine
Methionine
