BIO CHEM 6 Flashcards
Which of the following statements regarding cyclin-dependent protein kinase is not correct?
Their activity is regulated by cyclins
They can alter the activity of proteins involve in the progression of cells through cell cycle
Their activity fluctuates during cell cycle
Each type of cell contains one specific form
Their activity is regulated by changes in gene expression, protein phosphorylation and proteolysis
Each type of cell contains one specific form
Which of the following statements regarding cyclins is not correct?
They can become linked to ubiquitin
They catalyze the phosphorylation of protein
They contain specific amino acid sequence that target them for proteolysis
They are activated and degraded during cell cycle
They are activated and degraded during cell cycle
Ubiquitin is a
Protein kinase
Protease
Component of the electron transport system
Protein that tags another protein for proteolysis
Protein that tags another protein for proteolysis
Cdk2/cyclinE functions in
G2/M transition
G2
M
G1/S transition
G1/S transition
In which phase of cell cycle is DNA replicated?
G1 phase
S phase
G2 phase
M phase
S phase
Cyclin dependent kinases which control progression through cell cycle checkpoints are totally activated by which of the following
Binding to cyclin, plus phosphorylation by a Cdk activating protein kinase
Binding to cyclins
Phosphorylation by Cdk activating protein kinase
Phosphorylation by a tyrosine kinase
Binding to cyclin, plus phosphorylation by a Cdk activating protein kinase
At the end of each phase of cell cycle cyclins activating Cdks in that phase are inactivated irreversibly by
Multiple phosphorylations
De-phosphorylation
Ubiquitinylation
Destabilizing by proteolysis in a proteosome
Destabilizing by proteolysis in a proteosome
At which cell cycle checkpoint, cell cycle is halted if cell’s DNA is damaged
G1 – S
S – G2
G2 – M
G0 – G1
G1 – S
Which of the following occurs in meiosis but not in mitosis?
Attachment of spindle fibers to kinetochore
Replication of DNA prior to start of cell division
Separation of sister chromatids at anaphase
Pairing of homologous chromosomes at metaphase plate
Pairing of homologous chromosomes at metaphase plate
Passage of a cell through stages of cell cycle is controlled by a protein kinase that phosphorylates many different proteins at appropriate times
Cdk activating kinase
Cyclin-dependent kinase
Cyclins
Tyrosine kinase
Cyclin-dependent kinase
Proto-oncogenes can be transformed to oncogenes by all of the following mechanisms except
Elimination of their start signals for translation During a viral infection cycle Chromosomal rearrangements Chemically induced mutagenesis Radiation induced mutation
Elimination of their start signals for translation
Oncogenes do not encode for
Trans-membrane protein receptors
Growth factors
DNA-dependent RNA polymerase
Cytoplasmic G-proteins and protein kinases
DNA-dependent RNA polymerase
Programmed cell death is termed as
Metastasis
Apoptosis
Proliferation
Mitotic termination
Apoptosis
Which of the following could be coded by a tumor-supressor gene?
A protein that helps prevent progression through cell cycle
A protein that helps prevent apoptosis
A protein that codes for a DNA repair enzyme
A protein that forms part of a growth factor signaling pathway
A protein that helps prevent progression through cell cycle
How does Ras oncogene contribute to cancers?
It codes for an anti-apoptotic protein, produced in abnormally large amounts
It codes for a GTPase switch protein, which in its mutated form cannot be switched off
It codes for a transcription factor produced abnormally in large amounts
A growth factor that is continually active
It codes for a GTPase switch protein, which in its mutated form cannot be switched off
Which property of p53 enables it to prevent the development of cancer?
It is a transcription factor that causes protein production which stimulates the cell cycle
It prevents replication of cells with damaged DNA
It prevents cells from triggering apoptosis
It stimulates synthesis of DNA repair enzymes that replace telomere sequence lost during cell division
It prevents replication of cells with damaged DNA
The characteristic of malignant other than a benign tumor is
Undergoes metastasis
Develops blood supply
Cell divides an unlimited number of times
Grows without needing a growth signal
Undergoes metastasis
The mutation which cannot give rise to an oncogene
Addition or deletion of a base producing a nonsense message and an inactive protein product
A point mutation changing just one amino acid in protein product
A translocation, putting gene under control of strong promoter producing over expression
A point mutation producing stop codon, premature termination
Addition or deletion of a base producing a nonsense message and an inactive protein produc
Which of the following about Rb tumor suppressor protein is correct?
It binds E2F transcription factor and prevents cell from entering S phase until a mitogenic signal is received
It is activated when phosphorylated by Cdk
It is a transcription factor
When a mitogenic signal is received, it binds the transcription factor E2F and thus stimulates the cell to enter S phase
It binds E2F transcription factor and prevents cell from entering S phase until a mitogenic signal is received
Migration of cancerous cells from the site of origin to other part of the body forming secondary tumors is called
Diapedesis
Metastasis
Proliferation
Apoptosis
Metastasis
If enthalpy change for a reaction is zero, then ∆G° equals to
-T∆S°
T∆S°
-∆H°
lnkeq
-T∆S°
∆G° is defined as the
Residual energy present in the reactants at equilibrium
Residual energy present in the products at equilibrium
Difference in the residual energy of reactants and products at equilibrium
Energy required in converting one mole of reactants to one mole of products
Energy required in converting one mole of reactants to one mole of products
For a reaction if ∆G° is positive, then
The products will be favored
The reactants will be favored
The concentration of the reactants and products will be equal
All of the reactant will be converted to products
The reactants will be favored
Unfolding of regular secondary protein structure causes
Large decrease in the entropy of the protein
Little increase in the entropy of protein
No change in the entropy of the protein
Large increase in the entropy of the protein
Large increase in the entropy of the protein
The study of energy relationships and conversions in biological systems is called as
Biophysics
Biotechnology
Bioenergetics
Microbiology
Bioenergetics
The relationship between K‘eq and ∆G‘° is
∆G‘° = RTlnK‘eq ∆G‘° = -RTK‘eq ∆G‘° = RK‘eq ∆G‘° = -RK‘eq
∆G‘° = -RTK‘eq
What does first law of thermodynamics state?
Energy can neither be destroyed nor created
Energy cannot be 100 percent efficiently transformed from one type to another
All living organisms are composed of cells
Input of heat energy increases the rate of movement of atoms and molecules
Energy can neither be destroyed nor created
If ∆G‘° of the reaction A → B is -40kJ/mol under
standard conditions then the reaction
Will never reach equilibrium
Will not occur spontaneously
Will proceed at a rapid rate
Will proceed from left to right spontaneously
Will proceed from left to right spontaneously
What is the relationship between ∆G and ∆G‘°?
∆G = ∆G‘° + RTln([products]/[reactants]) ∆G = ∆G‘° – RTln([products]/[reactants]) ∆G = ∆G‘° + RTln([reactants]/[products]) ∆G = ∆G‘° – RTln([reactants]/[products])
∆G = ∆G‘° + RTln([products]/[reactants])
Which of the following statements is false?
The reaction tends to go in the forward direction if ∆G is large and positive
The reaction tends to move in the backward direction if ∆G is large and negative
The system is at equilibrium if ∆G = 0
The reaction tends to move in the backward direction if ∆G is large and positive
The reaction tends to move in the backward direction if ∆G is large and positive
Anabolism and catabolism are chemically linked in the form of
ADP
ATP
Phosphodiester linkage
ASP
ATP
Which of the following statements is false about ATP hydrolysis?
It is highly exergonic
Activation energy is relatively high
∆G‘°=-30.5kJ/mol
∆G‘°=30.5kJ/mol
d. ∆G‘°=30.5kJ/mol
An endergonic reaction
Proceeds spontaneously
Does not require activation energy
Releases energy
Requires energy
Requires energy
An exergonic reaction
Proceeds spontaneously
Does not require activation energy
Releases energy
Requires energy
Releases energy
Phosphoryl groups are derivatives of
Phosphorous acid
Phosphoric acid
Acetic acid
Citric acid
Phosphoric acid
Water does a nucleophilic attack on phosphate monoester producing
Phosphorous chloride
Phosphorous sulfide
Inorganic phosphate
Organic phosphate
Inorganic phosphate
The phosphate groups used during glycolysis are
Organic
Inorganic
Neutral
None
Inorganic
Which of the following is false about acetyl-coA?
It is a thioester
It has a large, negative standard free energy of hydrolysis
It contains phosphorous atom in the position occupied by an oxygen atom in oxygen esters
It contains sulfur atom in the position occupied by an oxygen tom in oxygen esters
It contains phosphorous atom in the position occupied by an oxygen atom in oxygen esters
An example for chemical to osmotic energy conversion that occurs in living organisms
ATP-driven muscle contraction
ATP-dependent photon emission in fireflies
light-induced electron flow in chloroplasts
ATP-driven active transport across a membrane
ATP-driven active transport across a membrane
An example for chemical to electromagnetic energy conversion that occurs in living organisms
ATP-driven muscle contraction
ATP-dependent photon emission in fireflies
light-induced electron flow in chloroplasts
ATP-driven active transport across a membrane
ATP-dependent photon emission in fireflies
An example for chemical to mechanical energy conversion that occurs in living organisms
ATP-driven muscle contraction
ATP-dependent photon emission in fireflies
light-induced electron flow in chloroplasts
ATP-driven active transport across a membrane
ATP-driven muscle contraction
An example for electromagnetic to electrical energy conversion that occurs in living organisms
ATP-driven muscle contraction
ATP-dependent photon emission in fireflies
light-induced electron flow in chloroplasts
ATP-driven active transport across a membrane
light-induced electron flow in chloroplasts
Which of the following statements about redox potential is false?
NADH/NAD+ redox pair has the least redox potential
Oxygen/H2O redox pair has the highest redox potential
The components of electron transport chain are organized in terms of their redox potential
The redox potential of a system is usually compared with the potential of the hydrogen electrode
NADH/NAD+ redox pair has the least redox potential
Which out of the following is not a flavoprotein?
Succinate dehydrogenase
Cytochrome c
Xanthine oxidase
NADH dehydrogenase-Qreductase
Cytochrome c
Which out of the following has the highest redox potential?
NAD
FMN
FAD
O2
O2
Which one out of the following is not a NAD+ requiring enzyme?
Lactate dehydrogenase
Pyruvate dehydrogenase complex
Maltate dehydrogenase
Acyl co-A dehydrogenase
Acyl co-A dehydrogenase
Which of the following enzyme catalyses the direct transfer and incorporation of O2 into a substrate molecule is
Reductase
Oxidase
Oxygenase
Peroxidase
Oxygenase
Which of the following statements is incorrect about oxidase?
They catalyze reactions involving hydrogen peroxide
They catalyze reaction using O2 as a hydrogen acceptor
They catalyze reactions using niacin as coenzyme
They catalyze reactions of direct incorporation of O2 into the substrate
They catalyze reaction using O2 as a hydrogen acceptor
Loss of electrons can be termed as
Metabolism
Anabolism
Oxidation
Reduction
Oxidation
Gain of electrons can be termed as
Metabolism
Anabolism
Oxidation
Reduction
Reduction
Which of the following enzyme catalyzes the first step in the catabolism of ethanol?
Alcohol dehydrogenase
Lactate dehydrogenase
Glutamate dehydrogenase
Malate dehydrogenase
Alcohol dehydrogenase
Which out of the following enzymes can utilize both NAD+ and NADP+ as a coenzyme?
Glutamate dehydrogenase
Alcohol dehydrogenase
Aldehyde dehydrogenase
Glycerol-3-P ddehydrogenase
Glutamate dehydrogenase
Which of the following enzyme catalyzes the first step of glycolysis?
Hexokinase
Pyruvate kinase
Glucokinase
Phosphofructokinase-1
Hexokinase
The general term used for the anaerobic degradation of glucose to obtain energy is
Anabolism
Oxidation
Fermentation
Metabolism
Fermentation
Whenever the cell’s ATP supply is depleted, which of the following enzyme’s activity is increased?
Hexokinase
Pyruvate kinase
Glucokinase
Phosphofructokinase-1
Phosphofructokinase-1
Cleavage of Fructose 1, 6-biophosphate yields
Two aldoses
Two ketoses
An aldose and a ketose
Only a ketose
An aldose and a ketose
Dihydroxyacetone phosphate is rapidly and reversibly converted to
Glyceraldehyde 3-phosphate
1, 3-bis-phosphoglycerate
Fructose 1, 6-bisphosphate
Fructose 6-phosphate
Glyceraldehyde 3-phosphate
The first step in the payoff phase of glycolysis is
Reduction of 1, 3-bisphosphoglycerate to glyceraldehyde 3-phosphate
Oxidation of glyceraldehyde 3-phosphate to 1, 3-bisphosphoglycerate
Reversible conversion of dihydroxyacetone phosphate to glyceraldehyde 3-phosphate
Irreversible conversion of dihydroxyacetone phosphate to glyceraldehyde 3-phosphate
Oxidation of glyceraldehyde 3-phosphate to 1, 3-bisphosphoglycerate
The substrate used in the last step of glycolysis is
Glyceraldehyde 3-phosphate
Pyruvate
Phosphoenolpyruvate
1, 3-bisphosphoglycerate
Phosphoenolpyruvate
High concentration of glucose 6-phosphate is inhibitory to
Hexokinase
Pyruvate kinase
Glucokinase
Phosphofructokinase-1
Hexokinase
The product formed in the first substrate level phosphorylation in glycolysis is
Pyruvate
3-phosphoglycerate
1, 3-bisphosphoglycerate
2-phosphoglycerate
3-phosphoglycerate
Glycolysis converts
Glucose into pyruvate
Glucose into phosphoenolpyruvate
Fructose into pyruvate
Fructose into phosphoenolpyruvate
Glucose into pyruvate
The deficiency of which of the following enzyme leads to galactosemia?
Galactokinase
Pyruvate kinase
PFK-1
PFK-2
Galactokinase
The conversion of which of the following involves two nucleotide derivatives?
Galactose 1-phosphate to glucose 1-phosphate
Galactose 1-phosphate to fructose 1-phosphate
Fructose 1-phosphate to glucose 1-phosphate
Lactose 1-phosphate to glucose 1-phosphate
Galactose 1-phosphate to glucose 1-phosphate
Which of the following enzyme is responsible for the conversion of glucose 1-phosphate to glucose 6-phosphate?
Glycogen phosphorylase
Isomerase
Phosphoglucomutase
Epimerase
Phosphoglucomutase
The product formed in the isomerization of mannose 6-phosphate
Fructose 6-phosphate
Glucose 6-phosphate
2-phosphoglycerate
3-phosphoglycerate
Fructose 6-phosphate
Which of the following enzyme is present in saliva?
Hexokinase
Alpha amylase
Fructokinase
Triose kinase
Alpha amylase
Which of the following conversions is not catalyzed by hexokinase?
D-Glucose to glucose 6-phosphate
D-Fructose to fructose 6-phosphate
D-Mannose to mannose 6-phosphate
D-Fructose to fructose 1-phosphate
D-Fructose to fructose 1-phosphate
Hydrolysis of lactose yields
D-galactose and D-glucose
D-glucose and D-glucose
D-galactose and D-fructose
D-fructose and D-glucose
D-galactose and D-glucose
Hydrolysis of sucrose yields
D-galactose and D-glucose
D-glucose and D-glucose
D-galactose and D-fructose
D-fructose and D-glucose
D-fructose and D-glucose
Maltose hydrolysis yields
D-galactose and D-glucose
2-Dglucose
n-Dglucose
2-Dfructose
2-Dglucose
Dextrin hydrolysis yields
D-galactose and D-glucose
2-Dglucose
n-Dglucose
2-Dfructose
n-Dglucose
Which of the following is true about the enzyme producing NADH from a triose phosphate in the glycolytic pathway?
It produces 1, 3-biphosphoglycerate and NADH
It catalyzes irreversible reaction
It uses NAD+ and dihydroxyacetone ph
zosphate as substrates
It uses FADH2 and glyceraldehyde 3-phosphate as substrates
It produces 1, 3-biphosphoglycerate and NADH
The major factor(s) determining whether glucose is oxidized by aerobic or anaerobic glycolysis is/are
Ca2+
FADH2
NADH and the ATP/ADP ratio
Presence of high AMP
NADH and the ATP/ADP ratio
When glucose is converted to lactate by anaerobic glycolysis, equivalent number of ATPs derived is?
1
2
3
4
2
molecules of lactate during anaerobic glycolysis, which of the following statements is false?
Glyceraldehyde 3-P dehydrogenase reaction produces 2 ATP molecules
Lactate dehydrogenase reaction produces no ATP
Pyruvate kinase reaction produces 2 ATP molecules
Phosphofructokinase-1 reaction uses 1 ATP molecule
Glyceraldehyde 3-P dehydrogenase reaction produces 2 ATP molecules
In the reduction of pyruvate to lactate, which of the following is regenerated?
H+
NADH
NAD+
Na+
NAD+
For its activity, pyruvate decarboxylase requires
Mg2+
Ca2+
Na+
H+
Mg2+
TPP (thiamine pyrophosphate) is derived from
Vitamin A
Vitamin B1
Vitamin C
Vitamin B2
Vitamin B1
- The end products in ethanol fermentation are
a. Ethanol and CO2
b. Ethanol and O2
c. Ethanol, H2 and CO2
d. Ethanol, O2 and CO2
Ethanol and CO2
Enzyme involved in the pathway of ethanol fermentation?
Hexokinase
Pyruvate decarboxylase
Pyruvate dehydrogenase
Pyruvate kinase
Pyruvate decarboxylase
Enzyme involved in the pathway of synthesis of acetyl-coA
Hexokinase
Pyruvate decarboxylase
Pyruvate dehydrogenase
Pyruvate kinase
Pyruvate dehydrogenase
Which of the following is not an important precursor of glucose in animals?
Lactate
Pyruvate
Glycerol
Glucose 6-phosphate
Glucose 6-phosphate
Which of the following statements is false about gluconeogenesis?
From the hydrolysis of tri-acyl-glycerol, fatty acids can be used as a carbon source
From red blood cells, lactate can be used as a carbon source
From the hydrolysis of tri-acyl-glycerol, glycerol is converted to glucose in gluconeogenesis
From muscle vigorous muscle activity, lactate can be used as a carbon source
From the hydrolysis of tri-acyl-glycerol, fatty acids can be used as a carbon source
The enzyme which catalyzes the conversion of pyruvate to oxaloacetate
Pyruvate carboxylase
Pyruvate dehydrogenase
Pyruvate kinase
Phosphofructokinase-1
Pyruvate carboxylase
Oxaloacetate is reduced to malate by
Pyruvate carboxylase
Malate dehydrogenase
Pyruvate kinase
Phosphofructokinase-1
Malate dehydrogenase
Gluconeogenesis involves conversion of
Glucose to pyruvate
Pyruvate to glucose
Phosphoenolpyruvate to glucose
Pyruvate to fructose
Pyruvate to glucose
Which of the following organisms cannot covert acetyl-coA derived from fatty acids into glucose?
Animals
Plants
Bacteria
Virus
Animals
- Formation of one molecule of glucose from pyruvate requires
4 ATP, 2 GTP and 2 NADH
3 ATP, 2 GTP and 2 NADH
4 ATP, 1 GTP and 2 NADH
2 ATP, 2 GTP and 2 NADH
4 ATP, 2 GTP and 2 NADH
Ethanol is oxidized to acetaldehyde in the liver cytoplasm by
Alcohol dehydrogenase
Alcohol carboxylase
Pyruvate carboxylase
Pyruvate kinase
Alcohol dehydrogenase
The main source of glucose carbons for gluconeogenesis is
Guanine
Alanine
Cysteine
Threonine
Alanine
Which of the following statements about gluconeogenesis is correct?
Pyruvate is first converted to phosphoenolpyruvate by phosphoenolpyruvate carboxykinase
Fructose 1, 6-biphosphatase converts fructose 1, 6-bisphosphate into fructose 1-phosphate
Glucose 6-phosphatase hydrolyzes glucose 6-phosphate to release glucose into the blood
Glucose 6-phosphatase hydrolyzes glucose 6-phosphate and is found in liver and muscle
Glucose 6-phosphatase hydrolyzes glucose 6-phosphate to release glucose into the blood
In the pentose phosphate pathway, the major products are
Ribulose and NADPH
Ribulose and NADH
Ribulose and NAD+
Ribulose and ATP
Ribulose and NADPH
The first reaction of the pentose phosphate pathway is
Oxidation of glucose 6-phosphate to 6-phosphoglucono-δ-lactone
Oxidation of 6-phosphogluconate to ketopentose ribulose 5-phosphate
Reduction of 6-phosphoglucono-δ-lactone to glucose 6-phosphate
Reduction of ketopentose ribulose 5-phosphate to 6-phosphogluconate
Oxidation of glucose 6-phosphate to 6-phosphoglucono-δ-lactone
Which of the following statements is correct about oxidative pentose phosphate pathway?
It generates NADH
It oxidizes NADPH to NADP+
The pathway supplies ribose 5-phosphate and NADPH in the quantities the cell requires
Glucose 6-phosphatase catalyzes the rate limiting reaction of the pathway
The pathway supplies ribose 5-phosphate and NADPH in the quantities the cell requires
Which one out of the following enzymes acts in pentose phosphate pathway?
Aldolase
Glycogen phosphorylase
Pyruvate kinase
q6-phosphogluconate dehydrogenase
q6-phosphogluconate dehydrogenase
Oxidation of 3 molecules of glucose by pentose phosphate pathway results in the production of
3 molecules of pentose, 6 molecules of NADPH and 3 molecules of CO2
4 molecules of pentose, 6 molecules of NADPH and 3 molecules of CO2
4 molecules of pentose, 3 molecules of NADPH and 3 molecules of CO2
3 molecules of pentose, 4 molecules of NADPH and 3 molecules of CO2
3 molecules of pentose, 6 molecules of NADPH and 3 molecules of CO2
The main function of pentose phosphate pathway is
Supply NADP+
Supply NADH
Supply energy
Supply pentoses and NADPH
Supply pentoses and NADPH
One of the following statements is correct about pentose phosphate pathway
It generates 6 moles of CO2 for each mole of glucose consumed
It generates 38 mol of ATP per mole of glucose consumed
It is a reductive pathway that consumes NADH
Present in plants but not in animals
It generates 6 moles of CO2 for each mole of glucose consumed
Which of the following statements is correct about reductive pentose phosphate pathway?
It is not reversible
Transketolase transfers 3 carbon units
Transaldose transfers 2 carbon units
Pentoses can provide glycolytic intermediates
Pentoses can provide glycolytic intermediates
The use of NADPH generated from pentose phosphate pathway cannot be
Can be oxidized in the electron transport chain to provide 38 ATPs
Used for the synthesis of fatty acids
Used for the macrophageal functions
Used for steroid synthesis
Can be oxidized in the electron transport chain to provide 38 ATPs
Conversion of xylulose 5-phosphate to ribulose 5-phosphate is catalyzed by
Phosphopentose epimerase
Transaldolase
Transketolase
Phosphopentose isomerase
Phosphopentose epimerase
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