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Biochem final

units 1-5 test

Which of the following compounds is capable of hydrogen bonding with like molecules? HOCH2CH2OH CH3NH2
Which of the following statements is true of weak acids dissolved in water? They are partially ionized in water
Which of the following solutions will be isotonic with 3M sucrose? 1 M Sodium sulfate (Na2SO4)
In contrast to inorganic catalysts, enzymes have an intricately shaped surface called the __________. Active site
Alcohol dehydrogenase without NAD+ is called a _______: Apoenzyme
The steady state assumption states that if K1 = the rate constant for ES formation K2 = the rate constant for ES dissociation K3 = the rate constant for product formation The rate of formation of ES is equal to the rate of its degradation over the course of the reaction
The expression of the Michaelis constant is equal to: Where K1 = the rate constant for ES formation K2 = the rate constant for ES dissociation K3 = the rate constant for product formation (K2 + K3)/K1
Which of the following statements is not true of a spontaneous process? The entropy value is negative
The oxidation of food molecules to form CO2 and H2O is a(n) _______ process. Exergonic
A process is spontaneous when dG^0 < 0
Which of the following is not an effect of hydrogen bonding on the physical properties of water? Increased boiling point Increased heat of fusion Increased melting point Increased heat of vaporization
Which of the following species can form a buffer system? Acetic acid/ Sodium acetate
The high heat of fusion of water is due to its _______________. Hydrogen bonding
Water can form how many hydrogen bonds? 4
Which of the following species would form a buffer with HPO4-2? H2PO4^-1
he strongest type of non covalent force is Hydrogen bonds
The noncovalent interaction between an amide and an alcohol would be which of the following? Hydrogen bonding
Which of the following molecules would form a micelle? CH3(CH2)10COO- Na +
Red blood cells are isotonic to a solution that is 0.9% sodium chloride (NaCl). These same cells are _____________ to a solution that is 0.9% sodium sulfate (Na2SO4). Hypotonic
Salt bridges in proteins are an example of _________. Ionic interactions
The sodium acetate/acetic acid buffer is 0.1 molar in sodium acetate and 0.5 molar in acetic acid. What is the concentration of the buffer? 0.6 molar
Which of the following would not form a suitable buffer? Hydrochloric acid/ chloride
Which of the following is a hydronium ion? H3O+
In classical thermodynamics which of the following is true? All systems are at or near equilibrium, All materials are at low concentration
Choose the molecule with the highest phosphate transfer potential. Phosphoenolpyruvate
In living organisms where does the increase in entropy takes place? Surroundings
A measure of a system’s internal energy is Enthalpy
The following statement is made by which law of thermodynamics? “At absolute zero the disorder of a perfect crystal approaches zero” Third Law
An organism at equilbrium with it's environment is said to be __________. Dead
To maintain a system far from equilibrium a constant input of _______ is required. Energy
The rate of a reaction can be determined from which of the following? None of the above are correct.
A living organism is what type of thermodynamic system? Open
Which of the following is described by the second law of thermodynamics? Entropy
Which of the following is described by the first law of thermodynamics? Enthalpy
The study of reaction rates is called ___________. Kinetics
Which of the following processes are driven by the hydrolysis of ATP? Biosynthesis of biomolecules Active transport of substances across membranes Mechanical work such as muscle contraction
Which of the following thermodynamic properties is the most useful criterion of spontaneity? Free energy
Which of the following statements regarding free energy changes is true? At equilibrium dG0 = O, Free energy is a state function
The law of the conservation of energy states that: The total energy of the universe is constant
The most important direct source of energy in the body is: ATP
The oxidation of food molecules to form CO2 and H2O is a(n) _______ process Exergonic
The minimum amount of energy required to bring about a chemical reaction is called: Activation energy
Consider the following reaction diagram. Which letter indicates the transition state? C
The lock and key model of enzyme activity proposes that each Enzyme binds a specific substrate because the active site and substrate have complementary structures.
The synthesis of enzymes in response to changing metabolic needs is referred to as: Enzyme induction
Which of the following is a coenzyme? NADP+
Alcohol dehydrogenase without NAD+ is called a _______: Apoenzyme
Which of the following classes of enzymes catalyze reactions involving the cleavage of bonds by the addition of water? Hydrolase
The expression of the Michaelis constant is equal to: Where K1 = the rate constant for ES formation K2 = the rate constant for ES dissociation K3 = the rate constant for product formation (K2 + K3)/K1
In the Lineweaver-Burk double reciprocal plot the slope is equal to _____. Km/Vmax
In the Lineweaver-Burk double reciprocal plot the vertical intercept is equal to ____. 1/Vmax
In the Lineweaver-Burk double reciprocal plot the horizontal intercept is equal to _________. –1/Km
In competitive inhibition, increasing the concentration of substrate: Increases the overall rate of the reaction
NADPH and NADH are coenzymes found in which class of enzymes? Dehydrogenases
Enzyme control is accomplished in which of the following ways? Genetic control Covalent modification Allosteric regulation Compartmentation
Zymogens are a feature of what type of enzymatic control? Covalent modification
Segregation of biochemical pathways into different organelles in an example of which type of enzymatic regulation? Compartmentation
An enzyme without it cofactor is called ________ Apoenzyme
The major site of alcohol detoxification is Liver
Consider the following diagram what constitutes the activation energy for the forward reaction C-A
Which of the following statements is not true of enzymes Catalyses the forward reaction only
Glycogen is stored as granules in the liver and _________________. skeletal muscles
The oxidative reactions of metabolism provide for most ATP production. In what specific part of the cell do these reactions occur? mitochondria
How many cycles of the citric acid cycle are required to completely oxidize all the pyruvate formed when a molecule of glucose undergoes glycolysis? 2
How many molecules of FADH2 are produced by the complete oxidation of one acetyl group by the citric acid cycle? 1
Which enzyme in the mitochondria is responsible for phosphorylation of ADP? ATP synthase
In glycogen synthesis, glycogen synthase catalyses the linking of glucose units to the growing glycogen chain by the formation of α (1, 4) glycosidic bonds. What is the immediate source of glucose for this reaction UDP-glucose
Of the several high-energy compounds produced in cells, which one is the principal energy storage compound? ATP
What is the net yield of ATP molecules per glucose molecule undergoing glycolysis? 2
How many NADH are produced for each glucose that enters glycolysis? 2
In the complete oxidation of an acetyl group in the citric acid cycle, how many molecules of each of the following are produced? (a) CO2, (b) NADH, (c) FADH2 (a) 2, (b) 3, (c) 1
The enzyme fumarase catalyzes the addition of water to fumarate. What is the product of this reaction? malate
What compound, when hydrolyzed, produces ADP, inorganic phosphate, and energy? ATP
Which of the following substances serves as an intermediate through which all cellular energy sources are interconvertible? acetyl CoA
Which statement is true concerning aerobic versus anaerobic metabolism? Aerobic metabolism is much more efficient than anaerobic metabolism.
The enzyme triose phosphate isomerase catalyzes the isomerization of dihydroxyacetone phosphate. What is the product of this reaction? glyceraldehyde-3-phosphate
In the first substrate-level phosphorylation in glycolysis, a phosphoryl group is transferred from 1, 3-bisphosphoglycerate to ADP, thus producing ATP. What is the other product of this reaction? 3-phosphoglycerate
Which of the following could be a starting material in gluconeogenesis? a fatty acid
Which statement is false concerning glycolysis? Glycolysis is the final step in the process to produce energy from food.
1/1 What substrate is converted into glucose-6-phosphate by the enzyme hexokinase? glucose
As the bond is broken to form ADP from ATP, energy is released which can drive biological processes.
How many molecules of ATP are produced by oxidative phosphorylation for each molecule of NADH produced in the citric acid cycle? 3
The enzyme succinate dehydrogenase catalyzes the oxidation of succinate. What is the product of this reaction? fumerate
What is the main starting material for the glycolysis pathway? glucose
What compound is produced by the transfer of the acetyl group of acetyl CoA to oxaloacetate? citrate
Which of the following substances, when present in high concentrations, inhibits the α-ketoglutarate dehydrogenase complex? succinyl CoA
How many molecules of ATP can be produced by the complete oxidation of one molecule of glucose by glycolysis and the citric acid cycle? 36
In oxidative phosphorylation, how many molecules of ATP are produced per molecule of NADH in the mitochondrion? 3
What is the missing product in the reaction shown? 1, 3-bisphosphoglycerate + ADP → 3-phosphoglycerate + ? ATP
The process which degrades fuel molecules, such as starch, to provide energy for the cells is called catabolism.
When one molecule of glucose undergoes alcohol fermentation, what products, and how many molecules of each of them, account for the 6 carbon atoms? 2 molecules of ethanol and 2 molecules of carbon dioxide
What is the term for the region of a mitochondrion that is enclosed by the inner membrane? matrix space
Where are the enzymes for the citric acid cycle located? mitochondrial matrix space
Which of the following compounds is a positive effector of the allosteric enzyme isocitrate dehydrogenase? ADP
Of the following classes of food molecules, which one contains the most energy per gram? fats
Muscle exercise leads to the production of __________ which is converted to ___________ by the liver. lactic acid; glucose
Coenzyme A has the function of carrying acetyl groups in the form of acetyl CoA to the citric acid cycle.
What is the missing product in the reaction shown? phosphoenolpyruvate + ADP → ATP + ? pyruvate
Which organ is the main site of gluconeogenesis? liver
What compound, in addition to glutamate, is produced in the transamination reaction in which alanine and α-ketoglutarate react? pyruvate
At the end of glycolysis, how many pyruvate molecules have been produced from 10 glucose molecules? 20
What substance is converted into fructose-6-phosphate by the enzyme phosphoglucoisomerase? glucose-6-phosphate
The liver takes up excess lactate from the blood. Into what product is the lactate first converted? pyruvate
What is the terminal electron acceptor in aerobic organisms? oxygen
Into what final product is glucose converted at the end of glycolysis? pyruvate
What is another name for the F0F1 complex involved in oxidative phosphorylation? ATP synthase
Which of the following compounds is the negative effector of the enzyme citrate synthase? ATP
What protein complex in the inner mitochondrial membrane allows protons to return to the matrix? F0F1
Under aerobic conditions glucose is completely oxidized to CO2 by way of the citric acid cycle.
Which coenzyme form must be reoxidized so that glycolysis can continue to produce ATP for the cell? NADH
In acetyl coenzyme A, the atom to which the acetyl group derived from pyruvate is bonded is ________. S = sulfur
In the pentose phosphate pathway, 3 molecules of glucose produce 2 molecules of fructose-6-phosphate and 1 of glyceraldehyde-3-phosphate. How many carbon atoms are unaccounted for in this statement, and what is their fate? Three, they are converted to carbon dioxide.
Which of the following compounds inhibits the pyruvate dehydrogenase complex? acetyl CoA
Which of the following compounds is produced when the enzyme aconitase catalyzes the dehydration of citrate? cis-aconitate
Depending on an animal’s metabolic needs, fatty acids may be converted to triacylglycerols, energy or __________. Used in membrane synthesis
Saturated fatty acids containing up to 16 carbon atoms are assembled in ________. Cytoplasm
The b-oxidation of fatty acids requires_________. All of the above are correct
_________, a product of the oxidation of odd-chain fatty acids, is converted to succinyl-CoA. Propionyl-CoA
Cholesterol is a precursor of _________. E) All of the above are correct
The rate limiting step in fatty acid synthesis is Acetyl-CoA carboxylation
In animals the function of peroxisomal b-oxidation appears to be E) Shortening of very long chain fatty acids
The carbon atoms of cholesterol are derived from _______. Acetyl CoA
___________ is used to transport fatty acids into the mitochondria. Carnitine
Which of the following is not one of the ketone bodies? beta-Methylglutarate
The conversion of squalene to cholesterol requires ________. NADPH
In conjugation reactions An insoluble molecule is made soluble by conversion to a derivative with a water soluble functional group
Oxidation of the carbon farthest from the carbonyl group of a fatty acid is called omega-oxidation
The conversion of acetyl-CoA to malonyl-CoA is inhibited by ________. All of the above are correct
Which of the following tissues cannot use fatty acids as a fuel? Brain
Glycerol from the hydrolysis of triacylglycerols is transported by the blood to the ____ Liver
Cyclic electron transport occurs when A chloroplast has a high NADPH/NADP+
During light dependent reactions energy captured by an organism’s photosystem is tranduced into which of the following? ATP
The principal regulator of photosynthesis is ___________. light
The net production of “fixed” carbon in the Calvin cycle is A) One molecule of glyceraldehyde-3-phosphate
Most of the carbon translocated throughout plants is in the form of Sucrose
In photosynthesis captured light energy is used to initially synthesize A and C
Photosystem I contains _______. p700
The Calvin cycle is sometimes referred to as All of the above are correct
In addition to an inner and outer membrane chloroplasts contain a third membrane called Thylakoid membrane
In photorespiration which of the following molecules are consumed? B, C and D are correct
In photosynthesis there is All of the above are correct
The following mechanism(s) reduce the impact of the process of photorespiration: D) Both B and C are correct
The most abundant enzyme on earth is Rubisco
All of the following statements concerning light are true except A) High frequency radiation such as gamma rays and X-rays, which have long wavelengths, are high energy.
Nitrogen fixation requires iron and ________ as cofactors. Mo
The most common intracellular reducing agent is Glutathione
In nitrogen fixation by microorganisms what gas other than ammonia is produced? Hydrogen
The glutamate family of amino acids includes all of the following except _____. Lysine
One-carbon carriers in metabolism include All of the above are correct
Inorganic nitrogen is initially assimilated into which of the following amino acids D) Glutamine
The major form of regulation of nitrogen fixation is _______. C) Transcriptional control of the nitrogen fixation genes
________ ATP molecules are required to convert one mole of nitrogen to two ammonia molecules. 16
Most aminotransferaes utilize ________as the recipient a-keto acid. A) alpha-Ketoglutarate
In plants fixed nitrogen is assimilated into __________. E) Glutamine
The six families of amino acids are glutamate, aromatic, serine, aspartate, pyruvate and _______. Histidine
The amino acids serine and _______ are preferentially used to synthesize glucose for export from the liver Alanine
Which of the following is not a characteristic N-terminal amio acid residue of long-lived proteins B) Bulky hydrophobic amino acids
The ultimate products of autophagy include B, C and D
A buildup of uric acid is characteristic of which of the following diseases? Gout
Stress proteins C) Are referred to as heat shock proteins
Autophagy is triggered by All of the above
Ammonia is transferred to the liver as Glutamine
Amino acids whose degradation yields a-ketoglutarate include all of the following except _________. Leucine
In muscle excess amino groups are transferred to _________ to produce glutamate C) alpha-Ketoglutarate
Covalently bound chains with _________ or more ubiquitin monomers are required to transfer a protein to the proteosome. 4
The major route for protein degradation is UPS
Urea is synthesized in which organ? Liver
In general, catabolism of amino acids begins with A) Removal of the amino group
Amino acids whose degradation yields acetyl-CoA include all of the following except Glutamate
Autophagy is C) Used to degrade worn out intracellular components
C) Used to degrade worn out intracellular components E) None of the above
In addition to urea humans also excrete waste nitrogen as A) Uric acid
In animals the vast majority of water soluble hormones are E) A and C
The most prominent mechanism to prevent excessive hormone synthesis is C) Feedback inhibition
The cells that line the small intestine, which are responsible for the absorption of nutrients into the body, are called Enterocytes
In a metabolic steady state the rate of anabolic processes is approximately equal to: A) Catabolic processes
Symptoms of uncontrolled diabetes mellitus include all of the following except Hypoglycemia
Receptor tyrosine kinases are transmembrane receptors that bind ligands such as E) All of the above
Leptin is secreted by which of the following tissues? Adipose tissue
The brain consumes about _______% of the body’s energy. 20
Which of the following is not a second messenger molecule? Steroids
Animals employing several mechanisms to prevent excessive hormone action and release. Examples include which of the following? All of the above are true
During fasting and prolonged starvation, skeletal muscle A) Protein is degrades to provide amino acids to the liver for gluconeogenesis
The most serious acute symptom of type 1 diabetes is B) Ketoacidosis
During periods of starvation muscle reduces its consumption of glucose. This spares its use for which of the following organs? brain
The principal target tissues of insulin include E) All of the above are correct
The organ responsible for the regulation of blood pH is Kidney
Urea synthesis is the responsibility of which organ of the body? Liver
Receptors for most water soluble hormones are located in what part of the cell? A) Plasma membrane
Steroid hormones E) All of the above are correct
An autoimmune disease caused by the destruction of the insulin producing beta cells of the pancreas is called E) Type I diabetes
The replisome consists of all of the following proteins except _________. D) Catabolic gene activator protein
The _____ are enzymes that catalyze the unwinding of duplex DNA. B) Helicases
SSB are C) Proteins that bind to single-stranded DNA
DNA polymerase b is believed to be involved in A) Eukaryotic DNA repair
DNA molecules are copied or replicated by a _______ mechanism. Semiconservative
The tangling of DNA strands during replication is prevented by _________. Topoisomerases
The rate of DNA synthesis in eukaryotes is approximately_________ nucleotides per ________ per replication fork. B) 50 / second
_______ is a form of intermicrobial DNA transfer that occurs when bacteriophage inadvertantly serve as carriers of bacterial DNA to the recipient cell. Tranduction
The initiation of transcription involves the binding of RNA polymerase to a specific sequence called a __________. Promoter
The reassortment of DNA sequences is called Recombination
DNA synthesis is called Replication
DNA transposition can cause gene ______. D) Both A and B are correct
Many promoters for RNA polymerase II contain a consensus sequence call the _______. TATA box
DNA is synthesized in which of the following directions? C) In the 5’ to 3’ direction on both DNA strands
All of the following play a role in DNA repair except ________. Ribozymes
In the absence of its inducer the lac operon remains repressed because of the binding of lac repressor to the _______. Operator
Eukaryotic gene expression is affected by all of the following except ______. E) None of the above are correct
The majority of genetic variations arise from B) Genetic recombination
Topoisomerases E) All of the above are correct
In higher eukaryotes replication begins with the B) Assembly of pre-initiation replication complex (preRC)
Light-induced repair will correct which of the following mutations? B) It will reverse thymine dimers
In nucleotide excision repair in relationship with the damage B) Bulky lesions are removed
Genomic libraries are produced by D) Shotgun cloning
Homology modeling facilitates A) Protein structure prediction
Protooncogenes are B) Normal genes that if mutated can promote carcinogenesis
An exonuclease is an enzyme that C) Removes nucleotides from the end of a polynucleotide strand
The average natural mutation rate for plants and animals is one mutation per ______ genes/generation. C) 100,000
____________ repair occurs only on a strand actively being transcribed B) Transcription coupling repair
__________ corrects replication proofreading errors. A) Mismatch repair
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