BIO CHEM 7 Flashcards
Which out of the following statements is true about regulation of metabolic pathway?
Most of the metabolic pathways are regulated
Most of the metabolic pathways are not regulated
Regulation of metabolic pathways always involves changing the amount of enzymes
Metabolic regulation always depends on control by hormones
Most of the metabolic pathways are regulated
The rate of breakdown of metabolites is termed as
Metabolic state
Metabolism
Steady state
Homeostasis
Steady state
Diminished delivery of oxygen to tissues is termed as
Hypoxia
Ischemia
Homeostasis
Metabolism
Hypoxia
Diminished flow of blood to tissues is termed as
Hypoxia
Ischemia
Homeostasis
Metabolism
Ischemia
Which of the following statements is true about the control of muscle glycogen phosphorylase?
It is activated by phosphorylation by an active phosphorylase kinase
It is allosterically activated by ATP
It is allosterically activated by cAMP
Normally it exists in active form
It is activated by phosphorylation by an active phosphorylase kinase
Which of the following is not a factor determining the activity of an enzyme?
Association with regulatory protein
Sequestration
Allosteric regulation
Nucleotides
Nucleotides
Which of the following statements is true?
High insulin/glucagon ratio activates lipolysis in muscle
High insulin/glucagon ratio inhibits lipolysis in liver
High insulin/glucagon ratio activates lipolysis in adipocytes
Low insulin/glucagon ratio activates lipolysis in adipocytes
Low insulin/glucagon ratio activates lipolysis in adipocytes
Which of the following type of metabolite is used for generating glucose under severe starvation conditions?
Amino acids
Fats
Glycogen
Starch
Amino acids
Which of the following statements is true about brain metabolism in starvation?
The brain can use glucogenic amino acids for energy
The brain can only use glucose as fuel
Up to a quarter of energy requirement of the brain can come from fatty acids
Up to a half of energy requirement of the brain can come from ketone bodies
The brain can use glucogenic amino acids for energy
ne of the following statements about the control of enzyme activity by phosphorylation is correct
Phosphorylation of an enzyme results in conformational change
Phosphorylation of an enzyme occurs only at specific tyrosine residues
Phosphorylation of an enzyme is carried out by phosphoprotein phosphatases
Enzyme control by phosphorylation is irreversible
Phosphorylation of an enzyme results in conformational change
Gluconeogenesis responds to which of the following?
Hormonal control
pH control
Temperature control
Blood control
Hormonal control
When blood sugar levels fall, glycolysis is halted in liver to allow
Homeostasis
Anaerobic respiration
Aerobic respiration
Gluconeogenesis
Gluconeogenesis
How many steps are catalyzed by same enzymes in both glycolysis and gluconeogenesis?
6
7
8
9
7
How many steps are catalyzed by different enzymes in glycolysis and gluconeogenesis?
2
3
4
5
3
Three reactions of glycolysis are so exergonic, which are not catalyzed by
Hexokinase
PFK-1
Pyruvate kinase
Pyruvate dehydrogenase
Pyruvate dehydrogenase
What are the effects of increased concentration of citrate?
Increases the inhibitory effect of ATP
Decreases the inhibitory effect of ATP
Increases the activity of ATP
Increases the activity of AMP
Increases the inhibitory effect of ATP
The second control point in gluconeogenesis is the reaction catalyzed by
Pyruvate kinase
Pyruvate dehydrogenase
PFK-1
FBPase-1
Which of the following statements is true about PFK-1?
It is stimulated by AMP and ADP
It is stimulated by citrate and ATP
It is inhibited by AMP and ADP
It is stimulated by citrate and ADP
It is stimulated by AMP and ADP
Which of the following statements is true regarding acetyl co-A?
It stimulates pyruvate dehydrogenase
It stimulates pyruvate carboxylase
It inhibits pyruvate carboxylase
It stimulates hexokinase
It stimulates pyruvate carboxylase
Which of the following is a potent regulator of glycolysis and gluconeogenesis?
Fructose 2, 6-bisphosphate
Fructose 1, 6-bisphosphate
Fructose 6-phosphate
Glucose 1, 6-bisphosphate
Fructose 2, 6-bisphosphate
Glucagon and epinephrine stimulate glycogen breakdown to glucose 6-phosphate
Directly by binding to glycogen phosphorylase
Indirectly by first stimulating adenylate cyclase to make cAMP
Only in the liver
Only in muscle cells
Indirectly by first stimulating adenylate cyclase to make cAMP
The compounds responsible for coordinated regulation of glucose and glycogen metabolism are
NADH
NAD+
Acetyl co-A
Fructose 2, 6-bisphosphate
Fructose 2, 6-bisphosphate
Glycogen synthase a is activated by
Phosphorylation catalyzed by GSK3
Dephosphorylation catalyzed by GSK3
Phosphorylation catalyzed by pyruvate kinase
Phosphorylation catalyzed by pyruvate carboxylase
Phosphorylation catalyzed by GSK3
Glucagon is released from
Muscle
Pancreas
Kidneys
Epithelial tissues
Pancreas
Glucose 6-phosphatase is present only in
Liver
Muscle
Epithelial tissues
Kidneys
Liver
Which of the following enzymes is involved in the positive regulation of glycolysis/gluconeogenesis?
Hexokinase II
Hexokinase IV
PFK-2/FBPase-2
Pyruvate kinase
PFK-2/FBPase-2
Which of the following enzymes is involved in fatty acid synthesis?
Hexokinase II
Hexokinase IV
PFK-2/FBPase-2
Pyruvate dehydrogenase
Pyruvate dehydrogenase
Which of the following is involved in triacylglycerol synthesis?
Hexokinase II
Acyl co-A glycerol transferases
PFK-2/FBPase-2
Pyruvate dehydrogenase
Acyl co-A glycerol transferases
Which of the following is involved in pentose phosphate pathway?
Glucose 6-phosphate dehydrogenase
Acyl co-A glycerol transferases
PFK-2/FBPase-2
Pyruvate dehydrogenase
Glucose 6-phosphate dehydrogenase
Which of the following enzyme’s gene expression is slowed by insulin?
Hexokinase II
Hexokinase IV
PEP carboxykinase
Pyruvate kinase
PEP carboxykinase
Flux control coefficient measures the
Steady state change
pH change
Temperature change
Hormonal change
Steady state change
What is the relation between elasticity coefficient, flux coefficient and response coefficient?
R = C.ε R = C⁄ε R = ε⁄C ε = C.R
R = C.ε
Which of the following is a measure of the effect of an enzyme’s concentration on flux through a multi-enzyme pathway?
Response coefficient
Elasticity coefficient
Flux control coefficient
Metabolic control
Flux control coefficient
Which of the following is a measure of how responsive the enzyme is to changes in the concentration of a metabolite?
Response coefficient
Elasticity coefficient
Flux control coefficient
Metabolic control
Elasticity coefficient
An expression for the experimentally determined change in flux through a pathway in response to a regulatory hormone or second messenger
Response coefficient
Elasticity coefficient
Flux control coefficient
Metabolic control
Response coefficient
Which of the following statements about the control of glycogen synthesis from blood glucose in myocytes is incorrect?
Insulin affects three of five steps in this pathway
The effects on transport and hexokinase activity
increase the flux towards glycogen
The change in glycogen synthase activity increases the flux towards glycogen
Hexokinase enzyme is involved
The change in glycogen synthase activity increases the flux towards glycogen
Some regulated enzymes control the flux through a pathway, this activity is
Regulation
Control
Metabolism
Anabolism
Control
Some regulated enzymes rebalance the level of metabolites in response to the change in flux, this activity is
Regulation
Control
Metabolism
Anabolism
Regulation
Metabolic control analysis does not suggests that
When the blood glucose level rises, insulin acts in muscle to increase glucose transport into cells by bringing GLUT4 to the plasma membrane
When the blood glucose level rises, insulin acts in muscle to induce the synthesis of PFK-1
When the blood glucose level rises, insulin acts in muscle to activate glycogen synthase by covalent alteration
When the blood glucose level rises, insulin acts in muscle to induce the synthesis of hexokinase
When the blood glucose level rises, insulin acts in muscle to induce the synthesis of PFK-1
Which of the following is the most influential in setting the flux through glycolysis?
Hexokinase
PFK-1
PFK-2
Both hexokinase and PFK-1
Hexokinase
Glutamate is metabolically converted to α-ketoglutarate and NH4+ by a process
Oxidative deamination
Transamination
Reductive deamination
Deamination
Oxidative deamination
Free ammonia combined with glutamate to yield glutamine by the action of
Glutaminase
Glutamine synthase
Glutamate dehydrogenase
Amino transferase
Glutamine synthase
Pyridoxal phosphate and its aminate form, pyridoxamine phosphate are tightly bound coenzymes of
Amino transferases
Glutaminase
Glutamine synthase
Glutamate dehydrogenase
Amino transferases
The necessary coenzyme for transamination reactions is
Pyridoxal phosphate
Thiamine pyrophosphate
NAD
Coenzyme A
Pyridoxal phosphate
The first step in the catabolism of most L-amino acids once they have reached the liver is promoted by
Amino transferases
Glutaminase
Glutamine synthase
Glutamate dehydrogenase
Amino transferases
The combined action of aminotransferase and glutamate dehydrogenase is referred as
Oxidative deamination
Transamination
Reductive deamination
Transdeamination
Transdeamination
Glutamine is converted to glutamate and NH4+ by
Amino transferases
Glutaminase
Glutamine synthase
Glutamate dehydrogenase
Glutaminase
Which of the following operates at an important intersection of carbon and nitrogen metabolism?
Amino transferases
Glutaminase
Glutamine synthase
Glutamate dehydrogenase
Glutamate dehydrogenase
Trypsinogen is converted to its active state by
Enteropeptidase
Glutaminase
Glutamine synthase
Glutamate dehydrogenase
Enteropeptidase
Which of the following hydrolyzes successive amino-terminal residues from short peptides?
Aminopeptidase
Enteropeptidase
Glutamine synthase
Glutamate dehydrogenase
Aminopeptidase
Urea production occurs almost exclusively in
Kidneys
Liver
Blood
Urine
Liver
The first amino group entering into urea cycle is
Carbomyl phosphate
Ornithine
Cituilline
Argininosuccinate
Carbomyl phosphate
The first enzyme in the pathway carbamoyl phosphate synthase I, is allosterically activated by
N-acetylglutamate
Acetyl coA
Glutamate
Carbamoyl phosphate
N-acetylglutamate
A second amino group is transferred to cituilline from
Aspartate
Glutamate
Alanine
Guanine
Aspartate
Nitrogen atoms of urea produced in the urea cycle are derived from
Ammonia and aspartic acid
Nitrate
Nitrite
Ammonia
Ammonia and aspartic acid
Products of urea cycle are
One molecule of urea, one molecule of ammonia, one molecule of ATP and one molecule of fumaric acid
One molecule of urea, one molecule of AMP, two molecule of ADP and one molecule of fumaric acid
One molecule of aspartic acid, one molecule of ammonia, one molecule of ATP and one molecule of fumaric acid
Two molecules of urea, two molecules of ammonia, one molecule of ATP and one molecule of fumaric acid
One molecule of urea, one molecule of AMP, two molecule of ADP and one molecule of fumaric acid
The carbon atom source while producing urea in the urea cycle is
CO2
Glucose
Aspartic acid
Arginine
CO2
Which of the following is not an essential amino acid?
Glycine
Leucine
Methionine
Histidine
Methionine
Urea cycle converts
Keto acids into amino acids
Amino acids into keto acids
Ammonia into a less toxic form
Ammonia into a more toxic form
Keto acids into amino acids
Inputs to one cycle of urea cycle are
One molecule of CO2, one molecule of ammonia, three molecule of ATP and one molecule of aspartic acid
One molecule of urea, one molecule of AMP, two molecule of ADP and one molecule of fumaric acid
One molecule of aspartic acid, one molecule of ammonia, one molecule of ATP and one molecule of fumaric acid
Two molecules of urea, two molecules of ammonia, one molecule of ATP and one molecule of fumaric acid
One molecule of CO2, one molecule of ammonia, three molecule of ATP and one molecule of aspartic ac
Which of the following amino acids are exclusively ketogenic?
Leucine
Asparagine
Threonine
Proline
Leucine
Which of the following are exclusively glucogenic?
Arginine
Leucine
Lysine
Threonine
Arginine
Which of the following yield acetyl co-A via aceto-acetyl co-A?
Leucine
Isoleucine
Threonine
Alanine
Leucine
Which of the following yield acetyl coA directly?
Phenylalanine
Isoleucine
Lysine
Alanine
Isoleucine
Which of the following produce pyruvate?
Leucine
Isoleucine
Lysine
Alanine
Alanine
Which of the following produce α-ketoglutarate?
Leucine
Threonine
Methionine
Proline
Proline
Which of the following produce succinyl co-A?
Leucine
Isoleucine
Arginine
Alanine
Isoleucine
Fumarate is produced from four carbon atoms of
Tyrosine
Isoleucine
Threonine
Alanine
Tyrosine
Which of the following produce oxaloacetate?
Aspartate
Isoleucine
Threonine
Alanine
Aspartate
The branched chain amino acid is not
Leucine
Isoleucine
Valine
Alanine
Alanine
Protein that contains nucleic acid derivative of riboflavin is called
Nucleic acid
Amino acid
Flavoprotein
None
Flavoprotein
NADP-linked dehydrogenase catalyzes
Glucose 6-phosphate+NADP+ ↔ 6-phosphogluconate + NADPH + H+
Lactate + NAD+ ↔ pyruvate + NADH + H+
Pyruvate + CoA + NAD+ ↔ acetyl-CoA + CO2 + NADH + H+
L-Malate + NAD+ ↔ oxaloacetate + NADH + H+
Glucose 6-phosphate+NADP+ ↔ 6-phosphogluconate + NADPH + H+
A lipid-soluble benzoquinone with a long isoprenoid side chain
Ubiquinone
Cytochrome b
Cytochrome c
Cytochrome a
Ubiquinone
The only membrane bound enzyme in the citric acid cycle is
Succinate dehydrogenase
NADH dehydrogenase
ATP synthase
Acyl co-A dehydrogenase
Succinate dehydrogenase
The first step in the β oxidation of fatty acyl co-A is catalyzed by
Succinate dehydrogenase
NADH dehydrogenase
ATP synthase
Acyl co-A dehydrogenase
Acyl co-A dehydrogenase
Complex 1 is also called
a. NADH dehydrogenase
b. Succinate dehydrogenase
c. Cytochrome bc1 complex
d. Cytochrome oxidase
NADH dehydrogenase
Complex 2 is also called
NADH dehydrogenase
Succinate dehydrogenase
Cytochrome bc1 complex
Cytochrome oxidase
Succinate dehydrogenase
Complex 3 is also called
NADH dehydrogenase
Succinate dehydrogenase
Cytochrome bc1 complex
Cytochrome oxidase
Cytochrome bc1 complex
Complex 4 is also called
NADH dehydrogenase
Succinate dehydrogenase
Cytochrome bc1 complex
Cytochrome oxidase
Cytochrome oxidase
In mitochondria, hydride ions are removed from substrates by
NAD-linked dehydrogenases
NADP-linked dehydrogenases
ATP synthase
Succinate dehydrogenases
NAD-linked dehydrogenases
Which of the following is the prosthetic group of NADH dehydrogenase?
NADH
FAD
NADPH
FMN
FMN
Effect of valinomycin on oxidative phosphorylation does not involve
pH gradient across the inner mitochondrial membrane decreases
Rate of flow of electrons increases
Rate of oxygen consumption increases
Net yield of ATP decreases
pH gradient across the inner mitochondrial membrane decreases
If mitochondria were blocked at the site of NADH oxidation and were treated with succinate as substrate, what would the P : O ratio is?
Same as that normally produced by succinate
One more than normally produced by succinate
One less than normally produced by succinate
Zero
Same as that normally produced by succinate
If 2, 4-dinitrophenol is added to tightly coupled mitochondria that are actively oxidizing succinate
Electron flow will continue but ATP synthesis will not occur
Electron flow will continue but ATP synthesis will be increased
Electron flow will cease but ATP synthesis will continue
Both electron flow and ATP synthesis will be ceased
Electron flow will continue but ATP synthesis will not occur
If the oxidative phosphorylation was uncoupled in the mitochondria then there is a/an
Decreased concentration of ADP in the mitochondria
Decreased oxidative rate
Increased inorganic phosphate in the mitochondria
Decreased production of heat
Increased inorganic phosphate in the mitochondria
If rotenone is added to the mitochondrial electron transport chain
Succinate oxidation remains normal
P: O ratio of NADH is reduced from 3:1 to 2:1
Oxidative phosphorylation is uncoupled at site I
Rate of NADH oxidation is diminished to two-thirds of its initial value
Succinate oxidation remains normal
Which of the following takes place in substrate level phosphorylation?
Oxidation of one molecule of substrate is linked to synthesis of more than one ATP molecule
High energy intermediate compounds cannot be isolated
Only mitochondrial reactions participate in ATP formation
Substrate reacts to form a product containing a high energy bond
Substrate reacts to form a product containing a high energy bond
Chemiosmotic hypothesis does not involve
Only proton transport is strictly regulated, other positively charged ions can diffuse freely across the mitochondrial membrane
ATPase activity is reversible
Proton flow in to the mitochondria depends on the presence of ADP and Pi
Electron transport by the respiratory chain pumps protons out of the mitochondria
Only proton transport is strictly regulated, other positively charged ions can diffuse freely across the mitochondrial membrane
Out of the following the one having highest redox potential is
Ubiquinone
O2
FMN
NAD
O2
Which of the following accepts only one electron?
Cytochrome b
Coenzyme Q
FMN
FAD
Cytochrome b
The proposal of chemiosmotic hypothesis was by
Peter D. Mitchell
Charles Darwin
Mendele
Alfred Russell
Peter D. Mitchell
ATP synthesis by chemiosmosis is by
ATP dehydrogenase
Gyrase
ATP synthase
Dehydrogenase
ATP synthase
The measure of potential energy stored as combination of proton and voltage gradients across membrane is termed as
Proton motive force
Electron motive force
Molecule motive force
Ion motive force
Proton motive force
The transport of acyl co-A for oxidation using a shuttle involves formation of the intermediate
Acyl coenzyme A
3 acetyl co-A
Acyl cartinine
None
Acyl cartinine
Three identical β subunits of the F1 complex during ATP synthesis have
Different affinities for ATP and ADP
Similar affinities for ADP and ATP
Different affinities for ADP but not ATP
Different affinities for ATP but not ADP
Different affinities for ATP and ADP
The acyl co-A formed in the cytosol is transported to
Mitochondrial matrix
Microsomes
ER
Remains in cytosol
Mitochondrial matrix
Every cycle of β-oxidation produces
1 FAD, 1 NAD+ and 2 CO2 molecules
1 FADH2, 1 NADH and 1 acetyl co-A
1 FADH2, 1 NAD+ and 1 acetyl co-A
1 FAD, 1 NADH and 2 CO2 molecules
1 FADH2, 1 NADH and 1 acetyl co-A
Membrane potential and proton gradient
Cancel one another when uncouplers are present
Reinforce one another when respiratory inhibitors are present
Are sufficient, separately to make ATP from ADP + Pi
Are required to make ATP
Are required to make ATP
Long-chain fatty acids are oxidized step-wise in one carbon units starting from
Carboxyl end
Aliphatic end
a and b
None
Carboxyl end
Maximum energy per gram on oxidation is yielded from
Starch
Fat
Glycogen
Protein
Fat
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