BICH 411: EXAM 1
50 Cards in this Set
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All are characteristics of metabolism EXCEPT...
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a free-flow unregulated process
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Most organisms show ______ in their major pathways of metabolism.
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marked similarity
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Likely the most ancient of the metabolic pathways in which energy is released from glucose and captured in the form of ATP under anaerobic conditions is called...
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glycolysis
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What is the relationship between photoautotrophs and heterotrophic cells?
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Photoautotrophs use light energy for synthesis of organic molecules while heterotrophs metabolize organic substances for fuel and building blocks.
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Which statement is most likely to be true concerning obligate anaerobes?
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These organisms cannot use oxygen as their final electron acceptor.
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All are characteristics of anabolism EXCEPT...
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all are true
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All are true about the relationship between catabolism and anabolism EXCEPT...
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They occur in ALL of the same organelles
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What are the final products of aerobic catabolism?
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CO2 and H2O
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The definition of an amphibolic pathway is...
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a pathway that is both anabolic and catabolic in nature
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Energy is generally extracted from phototrophs and chemotrophs by...
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oxidative-reduction reactions
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From the following types of organic molecules, the order of the most reduced to most oxidized is...
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hydrocarbon, alcohol, aldehyde, carboxylic acid, CO2
(B, D, A, E, C)
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The enzymes of glycolysis and those of the citric acid cycle are found in which cellular compartments in muscle cells?
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glycolysis in the cytoplasm and citric acid cycle in mitochondria
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Which of the following statements regarding nutrition is FALSE?
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Organisms can produce all of the essential energy yielding nutrients and micronutrients needed.
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Because of its highly polar nature, water is an excellent solvent for polar substances, but NOT for...
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hydrocarbons
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Amphiphilic (amphipathic) molecules include...
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fatty acids
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Water ionizes because...
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the larger electronegative oxygen atom strips the electron from one of its hydrogen atoms, leaving the proton to dissociate
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A plasma pH of 6.8 doesn't seem far too far away from a normal pH of 7.4, but at pH 6.8 the H+ concentration is ______ times greater than at pH 7.4 and results in severe acidosis.
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4
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The enzyme fumarase has a pH optimum of about 7.6. What would be the buffer of choice to study this enzyme?
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tris-hydroxymethyl aminomethane (Ka = 8.32x10^9, pKa = 8.07)
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A weak acid is 33% dissociated at pH 5.0. What is the pKa for this acid?
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5.3
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Thermodynamics does NOT...
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provide information on the rate of a reaction
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An interaction between two subunits of a protein was determined to have a deltaG = -27 kJ/mol. What is the Keq for the reaction at 25C?
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5.42x10^4
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All describe modified standard state for a thermodynamic parameter EXCEPT...
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mM for solutions
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To predict whether pairs of coupled reactions will proceed spontaneously...
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none are true
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The association of a protein with a fragment of DNA has a deltaG of -57 kJ/mol. Which equilibrium constant shown below is closest to that at 25C for the formation of this complex?
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10^10
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The conversion of glucose-6-phosphate to glucose-1-phosphate has a deltaG of 8.4 kJ/mol. What can be said about the value of Keq?
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Keq < 1
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For the first five steps of glycolysis, the appropriate sequence of enzymes is...
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hexokinase/glucokinase, phosphoglucoisomerase, phosphofructokinase-1, fructose bisphosphate aldolase, triose phosphate isomerase
(B, D, A, C, E)
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Hexokinase and glucokinase belong to the kinase subclass of what class of enzymes?
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transferase
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For phosphofructokinase-1...
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Low ATP stimulates the enzyme, and fructose-2,6-bisphosphate activates
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Class I aldolases are characterized by...
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a Schiff base intermediate
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Dihydroxyacetone phosphate is...
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isomerized to glyceraldehyde-3-phosphate by triose phosphate isomerase
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In the second half of the glycolytic pathway, ___ ATP molecules are produced and with the offset of ___ ATPs consumed in the first half, the net yield is ___ ATPs per glucose.
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four; two; two
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Glyceraldehyde-3-phosphate dehydrogenase belongs to what class of enzymes?
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oxidoreductases
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The reaction mechanism for glyceraldehyde-3-phosphate dehydrogenase involves ____ attack by a cysteine -SH group on the ____ carbon of the substrate to from a hemithioacetal.
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nucleophilic; carbonyl
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Substrate-level phosphorylation occurs in glycolysis in the reaction catalyzed by ____ and belongs to ____ class of enzymes.
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phosphoglycerate kinase; transferase
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A mutase catalyzes which of the reactions and belongs to which class of enzymes?
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3-phosphoglycerate <--> 2-phosphoglycerate; isomerase
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Which of the following amino acids provides the nucleophile in the reaction of class I aldolase?
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Lys
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Which of the following has the most highly exergonic hydrolysis (only the highest energy bond is hydrolyzed)?
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phosphoenolpyruvate
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Addition of water across a double bond, or removal of water to form a double bond, is catalyzed by a subclass of the lyase class of enzymes. Which of these enzymes would be a lyase?
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enolase
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PEP and 2-PG have similar amounts of potential metabolic energy with respect to decomposition to Pi, CO2 and H2O, but the enolase reaction...
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rearranges 2-PG into a form from which more potential energy can be released by hydrolysis.
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The high free energy change for the conversion of PEP to pyruvate is due largely to the ____ conversion of the relatively unstable ____ tautomer of pyruvate to the more stable ____ form following the phosphoryl group transfer step.
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favorable; enol; keto
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All of the following enzymes of glycolysis are allosterically regulated EXCEPT...
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glyceraldehyde-3-phosphate dehydrogenase
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NADH, ____ and ____ are products of glycolysis, and the NADH must be recycled to ____ before it becomes limiting in glycolysis.
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ATP; pyruvate; NAD+
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The oxidation of one mol of glucose by anaerobic glycolysis yields a net of...
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two mols of lactate and two mols of ATP
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In alcohol fermentation from glucose, the two oxidation-reduction reactions are catalyzed by...
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glyceraldehyde-3-phosphate dehydrogenase and alcohol dehydrogenase
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Seven of the ten reactions of glycolysis are reversible (deltaG near zero) and can be used in reverse of glycolysis for gluconeogenesis. The three irreversible reactions are catalyzed by...
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hexokinase, phosphofructokinase-1, pyruvate kinase
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Lactose intolerance is a deficiency of the enzyme ____ that results in the metabolism of lactose by ____.
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lactase; intestinal bacteria
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If glucose were labelled with 14C at carbon #6, what carbon of pyruvate would have the 14C?
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methyl carbon
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If yeast cells were given glucose that was labelled with 14C at carbon #3, where would the 14C be found after glycolysis under anaerobic conditions?
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CO2
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AMP is often used in the cytosol as an indicator of low cellular energy. Which of the following enzymes would be activated by AMP?
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phosphofructokinase-1
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Which of the following enzymes has two different binding sites for ATP, one a regulatory site and the other a substrate site?
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phosphofructokinase-1
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Gluconeogenesis - Flashcards