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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 |
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