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Biochem final
units 1-5 test
Question | Answer |
---|---|
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 |