BIO CHEM 1 Flashcards
Which of the following statements about the regulation of a metabolic pathway is correct?
Most 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 metabolic pathways are regulated.
Most metabolic pathways are regulated
Which of the following correctly exhibits an example of metabolic control?
In cases where the direction of a metabolic pathway has to be reversed the pathway is controlled at an irreversible step.
Regulatory changes in a pathway always occur slowly over periods of several hours or more.
Enzymes which are controlled are always those which catalyse the first reaction of the pathway.
Most enzyme control mechanisms are irreversible.
In cases where the direction of a metabolic pathway has to be reversed the pathway is controlled at an irreversible step.
Which of the following statements about the control of enzyme activity by phosphorylation is correct?
Phosphorylation of an enzyme is not a reversible process since it is a covalent modification.
Phosphorylation of an enzyme occurs by protein phosphatases.
Phosphorylation of an enzyme is an intracellular process and cannot occur in response to external signals.
Phosphorylation of an enzyme results in a conformational change.
Phosphorylation of an enzyme results in a conformational change.
Which of the following statements about the integration of fat and carbohydrate metabolism control is correct?
High insulin/glucagon ratio inhibits lipogenesis in liver.
High insulin/glucagon ratio activates lipolysis in muscle
Low insulin/glucagon ratio activates lipolysis in adipocytes.
Insulin-dependent glucose transporters are recruited to their functional membrane site when insulin levels are low.
Low insulin/glucagon ratio activates lipolysis in adipocytes.
Which type of metabolic fuel is utilised for generating glucose under conditions of severe starvation?
Glycogen.
Fats.
Starch.
Amino acids.
Amino acids.
Liver glycogen is used in fasting to provide glucose for use by other tissues including the brain. Muscle glycogen is not. What is the explanation for this?
Muscle does not have a debranching enzyme.
Muscle cannot degrade glycogen further than glucose-1-phosphate.
Muscle lacks glucose-6-phosphatase.
The liver provides all the glucose necessary for metabolism and there is no need for muscle to do the same.
Muscle lacks glucose-6-phosphatase.
Which is true of brain metabolism in starvation?
The brain can only use glucose as fuel.
Up to a quarter of the energy requirement of the brain can come from fatty acids.
Up to half the energy requirement of the brain can be met by ketone bodies.
The brain can use glucogenic amino acids for energy.
The brain can use glucogenic amino acids for energy.
Which of the following statements about the control of enzyme activity by phosphorylation is correct?
Enzyme control by phosphorylation is irreversible.
Phosphorylation of enzymes is carried out by phosphoprotein phosphatases.
Phosphorylation of enzymes only occurs at specific tyrosine residues.
Phosphorylation of an enzyme results in a conformational change.
Phosphorylation of an enzyme results in a conformational change.
Which of the following statements about the control of muscle glycogen phosphorylase is correct?
Muscle glycogen phosphorylase is allosterically activated by cAMP.
Muscle glycogen phosphorylase is allosterically activated by ATP.
Muscle glycogen phosphorylase normally exists in the a form.
Muscle glycogen phosphorylase is activated by phosphorylation by an active phosphorylase kinase.
Muscle glycogen phosphorylase is activated by phosphorylation by an active phosphorylase kinase
Which of the following statements about the control of glycogen synthase are correct? Please select all that apply.
Glycogen synthase kinase 3 is inactivated by a protein phosphatase.
Glycogen synthase kinase 3 is activated in the presence of insulin.
PKA and glycogen synthase kinase 3 phosphorylate glycogen synthase at different sites.
The phosphorylation by glycogen synthase kinase 3 is inhibited by insulin.
Insulin activates protein kinase B which phosphorylates glycogen synthase.
THESE 3 ARE CORRECT
PKA and glycogen synthase kinase 3 phosphorylate glycogen synthase at different sites.
The phosphorylation by glycogen synthase kinase 3 is inhibited by insulin.
Insulin activates protein kinase B which phosphorylates glycogen synthase.
Regulated metabolic pathways are:
irreversible. committed after the first step. usually regulated at the first step. compartmentalized in eukaryotes. All of the above are correct.
All of the above are correct.
- Each reaction in a metabolic pathway is:
controlled by the end product. catalyzed by a specific enzyme. irreversible. reversible. linked to at least two other pathways.
catalyzed by a specific enzyme.
The hormones, glucagon and epinephrine, stimulate glycogen breakdown to G-6-P
directly, by binding to glycogen phosphorylase.
indirectly, by first stimulating adenylate cyclase to make cAMP.
only in the liver.
only in muscle cells.
using ATP as the phosphoryl donor.
indirectly, by first stimulating adenylate cyclase to make cAMP.
Activation of the ___ kinase results in the activation of ___ kinase and thereby the phosphorylation of both glycogen phosphorylase and glycogen synthase.
pyruvate, phosphorylase
phosphorylase, cAMP-dependent protein
cAMP-dependent protein, phosphorylase
cAMP-dependent protein, pyruvate
None of the above.
cAMP-dependent protein, phosphorylase
When it functions as a “second messenger”, cAMP
acts outside the cell to influence cellular processes.
acts “second in importance” to AMP.
activates all cytosolic protein kinases.
activates the cAMP-dependent protein kinase.
binds to calmodulin causing it to bind Ca2+.
activates the cAMP-dependent protein kinase.
The major free energy sources for anabolic pathways are:
ATP and NADPH. ATP and NADP+. ADP and NADPH. ADP and NADP+. AMP or NADPH.
ATP and NADPH.
Which of the following compounds is responsible for coordinated regulation of glucose and glycogen metabolism?
NADH NAD+ acetyl-CoA fructose 2,6 bis-phosphate fructose 1,6 bis-phosphate
fructose 2,6 bis-phosphate
Opposing degradative and biosynthetic pathways:
use the same enzymes for many steps.
use different enzymes for steps that require large energy changes.
are coordinately regulated at the steps that use different enzymes.
are used in both directions in most organisms.
all of the above
all of the above
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
t 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
One 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
What makes water a liquid at room temperature?
Hydrogen bonds between water molecules
Covalent bonding
Noncovalent interactions
Van der Waals forces of attraction
Hydrogen bonds between water molecules
ΔG is negative for which of the following processes?
Melting of ice and evaporation of water
Oxidation of nitrogen
Oxidation of gold
Burning of chlorine
Melting of ice and evaporation of water
ΔH is positive for which of the following processes?
Oxidation of nitrogen
Melting of ice and evaporation of water
Oxidation of gold
Burning of chlorine
Melting of ice and evaporation of water
What is the factor that is responsible for salts like NaCl to dissolve in water easily?
Decrease in entropy
Increase in entropy
Increase in enthalpy
Decrease in enthalpy
Increase in entropy
Heat of vaporization of water is
2260 J/g
2260 kJ/g
1260 J/g
1260 kJ/g
2260 J/g
The bond dissociation energy of hydrogen bonds in a water molecule is
470 kJ/mole
470 J/mole
23 kJ/mole
23 J/mole
23 kJ/mole
The bond dissociation energy of O-H bond in a water molecule is
23 kJ/mole
470 kJ/mole
470 J/mole
23 J/mole
470 kJ/mole
Which of the following is a hypertonic solution?
Oceans
Freshwater habitats
0.45% sodium chloride
Red blood cells placed in fresh water
Oceans
Which of the following is a hypotonic solution?
10% dextrose in water
0.45% sodium chloride
5% dextrose in 0.9% sodium chloride
Oceans
0.45% sodium chloride
Which of the following is an isotonic solution?
0.9% sodium chloride
0.45% sodium chloride
Oceans
10% dextrose in water
0.9% sodium chloride
What is the concentration of OH– in a solution with a H+ concentration of 1.3×10-4 M?
- 7×10-10 M
- 7×10-9 M
- 7×10-11 M
- 7×10-12 M
7.7×10-11 M
Identify the triprotic acid from the following:
Carbonic acid
Bicarbonate
Glycine
Phosphoric acid
Phosphoric acid
Which of the following acids has the lowest pKa value?
Acetic acid
Sulphuric acid
Dil.HCl
Oxalic acid
Sulphuric acid
Which of the following bases has the highest pKa value?
NaOH
NaNO3
KNO3
KCl
NaOH
The degree of ionization does not depend on?
Temperature
Current
Nature of solvent
Concentration
Current
The hydrolysis constant of CH3COONa is given by:
Kh = Kw/Ka Kh = Kw/Kb Kh = Kw/Ka×Kb Kh = Ka + Kb
Kh = Kw/Ka
K1 and K2 for oxalic acid are 6.5×10-2 and 6.1×10-5respectively. What will be the [OH–] in a 0.01M solution of sodium oxalate?
- 6×10-6
- 4×10-1
- 2×10-6
- 3×10-8
1.2×10-6
If pKb for fluoride at 25°c is 10.83, the ionization constant of hydrofluoric acid in water at this temperature is:
- 52×10-3
- 75×10-4
- 38×10-2
- 74×10-5
6.75×10-4
Aqueous solution of the detergents are:
Neutral
Acidic
Basic
Amphoteric
Basic
If pH of solution of NaOH is 12.0 the pH of H2SO4 solution of same molarity will be:
- 0
- 0
- 7
- 0387
1.7
Which can act as buffer?
NH4Cl + HCl
CH3COOH + H2CO3
40ml of 0.1M NaCN + 20ml of 0.1M HCN
NaCl + NaOH
40ml of 0.1M NaCN + 20ml of 0.1M HCN
Calculate the pH of a mixture of 0.10M acetic acid and 0.20M sodium acetate. The pKa of acetic acid is 4.76.
- 1
- 1
- 1
- 1
5.1
- Calculate the pKa of lactic acid, given that when the concentration of lactic acid is 0.010M and the concentration of lactate is 0.087M, the pH is 4.80
- 0
- 9
- 3
- 1
3.9
Calculate the ratio of the concentrations of acetate and acetic acid required in a buffer system of pH 5.30.
- 2
- 3
- 4
- 5
3.5
Assertion A: pH of a buffer solution solution does not change on dilution.
Reason R: On dilution the ration of concentration of salt and acid (or base) remains unchanged.
A and R are true, R is the correct explanation of A
A and R are true, R is not correct explanation of A
A is true but R is false
A is false but R is true
A and R are true, R is the correct explanation of
Which of the following mixture in aqueous solution of equimolar concentration acts as a buffer solution?
HNO3 + NaOH
H2SO4 + KOH
NH4OH(excess) + HCl
NH4OH(excess) + HCl
1M NaCl and 1M HCl are present in an aqueous solution. The solution is:
Not a buffer solution with pH < 7
Not a buffer solution with pH > 7
A buffer solution with pH < 7
A buffer solution with pH > 7
Not a buffer solution with pH < 7
For an acid buffer solution the pH is 3. The pH can be increased by:
Increasing the concentration of salt
Increasing the concentration of acid
Decreasing the concentration of salt
Independent of concentration of acid & salt
Increasing the concentration of salt
The buffer capacity is equal to:
Δn / ΔpH
pH / Δn
± 1pKa
± 2pKa
± 1pKa
Buffer capacity is maximum when:
One mole of NH4Cl is added to two moles of NH4 OH
One mole of NH4Cl is added to one moles of NH4 OH
One mole of NH4Cl is added to one mole of NaOH
One mole of NaCl is added to one mole of NaOH
One mole of NH4Cl is added to one moles of NH4 OH
A) CuSO4 + 5H2O → CuSO4.5H2O
B) PCl3 + 3H2O → H3PO3 + 3HCl
The processes A and B are respectively:
Hydration and dehydration
Hydration and hydrolysis
Hydrolysis and hydrolysis
Hydration and hydration
Hydration and hydrolysis
Which of the following is not a condensation reaction?
ADP + inorganic phosphate ATP + H2O
R-OH + inorganic phosphate phosphate ester + H2O
R-COOH + inorganic phosphate Acyl phosphate + H2O
6CO2 + 6 H2O → C6H12O6 + 6CO2
6CO2 + 6 H2O → C6H12O6 + 6CO2
Which of the following is the correct equation?
CO2 + H2O → H2CO3
CO2 + H2O → HCO3
CO2 + H2O → H3CO3
CO2 + H2O → H2CO2
CO2 + H2O → H2CO3
Consider the following reaction, in the presence of light
2H2O + 2X → O2 + 2XH2
Which of the following statements is true?
X is electron-accepting specie
X is electron-donating specie
Water is an electron acceptor
Water neither donates nor accepts any electron
X is electron-accepting specie
Hydrolysis reactions are catalyzed by enzymes called:
Oxidoreductase
Ligase
Hydrolase
Isomerase
Hydrolase
What does it mean when we say that water acts as a “heat buffer”?
It keeps the temperature of an organism relatively constant as the temperature of the surroundings fluctuates.
It increases the temperature of an organism as the temperature of the surroundings increases
It decreases the temperature of an organism as the temperature of the surroundings increases
It increases the temperature of an organism as the temperature of the surroundings decreases
It keeps the temperature of an organism relatively constant as the temperature of the surroundings fluctuates.
Which of the following does not react with water?
Barium
Calcium
Beryllium
Strontium
Beryllium
What trend does the reactivity of group II elements follow with water?
Increases down the group
Decreases down the group
Does not follow any particular trend
No reaction
Increases down the group
Which among the following statements is true about the following chemical reaction?
3Fe(s) + 4H2O → Fe3O4 (s) + 4H2
Iron metal is getting reduced.
Water is acting as a reducing agent
Water is acting as an oxidizing agent
Water is getting oxidized
Water is acting as an oxidizing agent
Identify the products formed in the following reaction
CH3COOCH3 + H2O → A + B
CH3COOH and CH3OH
CH3COOOH and CH4
CO2 and C2H6
No reaction
CH3COOH and CH3OH
Identify the amino acids containing nonpolar, aliphatic R groups
Phenylalanine, tyrosine, and tryptophan
Glycine, alanine, leucine
Lysine, arginine, histidine
Serine, threonine, cysteine
Glycine, alanine, leucine
The two amino acids having R groups with a negative net charge at pH 7.0 are
Aspartate and glutamate
Arginine and histidine
Cysteine and methionine
Proline and valine
Aspartate and glutamate
If pK1 = 2.34 and pK2 = 9.60, then the isoelectric point pI is
- 87
- 97
- 67
- 94
5.97
Which of the following is a true statement?
Tryptophan and tyrosine are significantly more polar than phenylalanine
Leucine is commonly used as an ingredient in the buffers of SDS page
Aspartate is an essential amino acid
Lysine is a non-essential amino acid
Tryptophan and tyrosine are significantly more polar than phenylalanine
Which among the following is a non-essential amino acid?
Serine
Threonine
Lysine
Histidine
Serine
Which of the following is an essential amino acid?
Cysteine
Asparagine
Glutamine
Phenylalanine
Phenylalanine
Which of the following is an imino acid?
Alanine
Glycine
Proline
Serine
Proline
Which among the following is both glucogenic and ketogenic?
Isoleucine
Leucine
Lysine
Histidine
Isoleucine
An amino acid that yields acetoacetyl CoA during the catabolism of its carbon skeleton will be considered
Glycogenic
Ketogenic
Both glycogenic and ketogenic
Essential
Ketogenic
Number of chiral centers in isoleucine is
1
2
3
4
2
During the formation of the peptide bond which of the following takes place?
Hydroxyl group is lost from its carboxyl group of one amino acid and a hydrogen atom is lost from its amino group of another amino acid
Hydrogen atom is lost from its carboxyl group of one amino acid and a hydroxyl group is lost from its amino group of another amino acid
Hydroxyl group is lost from its carboxyl group of one amino acid and a hydroxyl group is lost from its amino group of another amino acid
Hydrogen atom is lost from its carboxyl group of one amino acid and a hydrogen atom is lost from its amino group of another amino acid
Hydroxyl group is lost from its carboxyl group of one amino acid and a hydrogen atom is lost from its amino group of another amino acid
Peptide bond is a
Covalent bond
Ionic bond
Metallic bond
Hydrogen bond
Covalent bond
A tripeptide has
3 amino acids and 1 peptide bond
3 amino acids and 2 peptide bonds
3 amino acids and 3 peptide bonds
3 amino acids and 4 peptide bonds
3 amino acids and 2 peptide bonds
The factor which does not affect pKa value of an amino acid is
The loss of charge in the α-carboxyl and α-amino groups
The interactions with other peptide R groups
Other environmental factors
Molecular weight
Molecular weight
Which of the following is a 39-residue hormone of the anterior pituitary gland?
Corticotropin
Glucagon
nsulin
Bradykinin
Corticotropin
The average molecular weight of an amino acid residue in a protein is about
128
118
110
120
110
Which of the following is not the classified form of conjugated proteins?
Lipoproteins
Glycoproteins
Metalloproteins
Complete proteins
Complete proteins
Which part of the amino acid gives it uniqueness?
Amino group
Carboxyl group
Side chain
None
Side chain
Which of the following information is responsible to specify the three-dimensional shape of a protein?
The protein’s peptide bond
The protein’s amino acid sequence
The protein’s interaction with other polypeptides
The protein’s interaction with molecular chaperons
The protein’s amino acid sequence
Unfolding of a protein can be termed as
Renaturation
Denaturation
Oxidation
Reduction
Denaturation
What are the following is not a factor responsible for denaturation of proteins?
pH change
Organic solvents
Heat
Charge
Charge
The salt which produces salting out effect during extraction of proteins is
NH4SO4
(NH4)2SO4
(NH4)3SO4
NaCl
(NH4)2SO4
In chromatography, a mobile phase can be
Only solid
Only gas
Solid or liquid
Liquid or gas
Liquid or gas
The pattern on paper in chromatography is called
Chroming
Chroma
Chromatograph
Chromatogram
Chromatogram
Which of the following statements about column chromatography is correct?
Resolution increases as the length of the column increases
Mobile phase is a porous solid material with appropriate chemical properties held in the column
Stationary phase is a buffered solution that percolates through mobile phase
Large proteins emerge from the column sooner than small ones
Resolution increases as the length of the column increases
Which of the following statements is true about size-exclusion chromatography?
During the separation of a mixture of proteins, protein with smallest molecular weight is eluted first
During the separation of a mixture of proteins, protein with largest molecular weight is eluted first
During the separation of a mixture of proteins, protein with largest molecular weight is eluted last
During the separation of a mixture of proteins, protein with largest molecular weight flow around the beads
During the separation of a mixture of proteins, protein with largest molecular weight is eluted first
Which of the following statements is true about affinity chromatography?
During the separation of a mixture of proteins, the protein which does not bind to ligand is eluted first
During the separation of a mixture of proteins, the protein which does not bind to ligand is eluted last
During the separation of a mixture of proteins, the protein which binds to ligand is eluted first
Unwanted proteins are eluted by ligand solution
During the separation of a mixture of proteins, the protein which does not bind to ligand is eluted first
Which of the following statements is true about ion-exchange chromatography?
It separates proteins according to their size
The column matrix with bound anionic groups is called cationic exchanger
The column matrix with bound anionic groups is called anionic exchanger
The column matrix with bound cationic groups is called cationic exchanger
The column matrix with bound anionic groups is called cationic exchanger
Which of the following statements is true about SDS polyacrylamide chromatography?
SDS polyacrylamide gel electrophoresis separates proteins on the basis of size
SDS polyacrylamide gel electrophoresis separates proteins on the basis of charge
SDS binds to proteins non-covalently with a stoichiometry of around one SDS molecule per three amino acids
SDS binds to proteins non-covalently with a stoichiometry of around one SDS molecule per one amino acid
SDS polyacrylamide gel electrophoresis separates proteins on the basis of charge
Which of the following statements is true about two-dimensional electrophoresis?
Separates proteins of identical molecular weight, same pI but different charge
Separates proteins of different molecular weight and different pI
Separates proteins of identical molecular weight that differ in pI
Isoelectric focusing is also termed as two-dimensional electrophoresis
Separates proteins of identical molecular weight that differ in pI
Which of the following statements is false?
The term activity refers to the total units of enzyme in a solution
The specific activity is a measure of enzyme purity
Specific activity increases during purification of an enzyme and becomes maximal and constant when the enzyme is pure
Specific activity decreases during purification of an enzyme and becomes maximal and constant when the enzyme is pure
Specific activity decreases during purification of an enzyme and becomes maximal and constant when the enzyme is pure
Which of the following statements is false?
Primary structure of a protein determines how it folds up into a unique three dimensional structure
Secondary structure of a protein determines how it folds up into a unique three dimensional structure
Three dimensional structure of a protein determines the function of a protein
Amino acid sequence is absolutely invariant for a particular protein
Secondary structure of a protein determines how it folds up into a unique three dimensional structure
Who deduced the double-helical structure of DNA?
Frederick Sanger
Mendel
Watson and Francis Crick
Anton van Leeuwenhoek
Watson and Francis Crick
Two chains of amino acids in an insulin molecule are held together by
Sulfide bridges
Disulfide bridges
Peptide bond
Covalent linkage
Disulfide bridges
Tertiary conformation of proteins is maintained by 3 types of bonds namely ionic, hydrogen and:
Sulfide
Disulfide
Covalent
Peptide
Disulfide
Hemoglobin is a
Monomer
Dimer
Trimer
Tetramer
Tetramer
Which of the following is false?
The two main types of secondary structure are the α helix and β pleet structures
α helix is a right handed coiled strand
The hydrogen bonding in a β-sheet is between strands rather than within strands
The hydrogen bonding in a β-sheet is within strands rather than between strands
The hydrogen bonding in a β-sheet is within strands rather than between strands
Native state of a protein can be disrupted by
Temperature
pH
Removal of water
Presence of hydrophilic surfaces
Presence of hydrophilic surfaces
Which of the following is true?
The disulfide bridges formed by reduction of the sulfhydryl groups on cysteine stabilizes protein tertiary structure
The disulfide bridges formed by oxidation of the sulfhydryl groups on cysteine destabilizes protein tertiary structure
The disulfide bridges formed by oxidation of the sulfhydryl groups on cysteine stabilizes protein tertiary structure
The disulfide bridges formed by reduction of the sulfhydryl groups on cysteine destabilizes protein tertiary structure
The disulfide bridges formed by oxidation of the sulfhydryl groups on cysteine stabilizes protein tertiary structure
Identify the wrong statement
Hemoglobin is a globular protein
Hemoglobin is a fibrous protein
Fibrous proteins are insoluble in water
Collagen is a fibrous protein
Hemoglobin is a fibrous protein
In 3° structure of proteins, folding and shaping is done by
Hydrophobic interactions
Polar interactions
Hydrogen bonding
None of the mentioned
Hydrophobic interactions
