bioc exam 3
the term "dark reactions" is a bit of a misnomer for the Calvin cycle. explain using NADPH, ATP, and the regulation of the pathway why "dark reactions" is a misleading name for the Calvin cycle. Would you expect plants to fix carbon at night?
"Dark reactions" is misleading because while the pathway does not use light directly, it still needs light to function. ATP and NADPH generated from dependent reactions are used int he Calvin cycle as energy and reducing equivalents, so in the dark there would not be enough energy to make carbohydrates. additionally rubisco is activated by an increase in pH, Mg, and ferredoxin which are all generated in the light-dependent reactions. Because of the reliance on molecules created by the energy in light, one would not expect plants to run the Calvin cycle at night
in terms of the number of ATP molecules produced from 1 molecule of glucose: what is the efficiency if the glucose molecule was stored in a 1-->6 linkage and then fully oxidized?
2 ATP molecules are used to store the glucose into the glycogen. glucose stored in a 1-->6 linkage in glycogen is released by the glucosidase activity of the debranching enzyme instead of glycogen phosphorylase, and thus, when a 1-->6 linkage is cleaved from glycogen it is released as a glucose molecule. fully oxidized glucose yields 32 ATP 32-2 ATP = 30 total ATP 30/32 ATP = 94%
if oxaloacetate is radioactively labelled at the carbon noted below (post lecture questions 21), how many steps of the citric acid cycle would it take to get radioactively labelled CO2? What enzyme catalyzed that reaction?
3 steps, catalyzed by isocitrate dehydrogenase the radioactively labelled carbon will be released as CO2. This happens in the reaction catalyzed by isocitrate dehydrogenase.
in terms of the number of ATP molecules produced from 1 molecule of glucose: what is the efficiency of storing glucose in a 1-->44 linkage in glycogen and hten completely oxidizing that glucose residue?
97% 1 ATP is used to create glucose-6-phosphate. 1 ATP (as UTP) is used to store the glucose in a 1-->4 linkage. glycogen phosphorylase uses phosphorolysis to brerak 1-->4 linkages at non-reducing ends to make glucose-1-phosphate, which can enter glycolysis as glucose-6-phosphate and yields 33 ATP 33-2 ATP = 31 total ATP if glucose is fully oxidized and not stored, it usually yields 32 ATP molecules, ,so the efficiency of storing glucose as a 1-->4 glycogen linkage is 31/32 = 97^
About half of the inner membrane proteins in mitochondria are involved in oxidative phosphorylation. Most of the other inner membrane proteins are involved in which ONE of the following? A. Transport of molecules into and out of the mitochondria. B. Oxidation of pyruvate to acetyl CoA. C Glycolysis D. Synthesis of citrate.
A
Based on the values in Table 14-1 which ONE of the following is the ΔG°′ for the reaction: Pyruvate + NADH + H+ ⟷⟷ Lactate + NAD+ A. -25 kJ per mole B. -8 kJ per mole C. +8 kJ per mole D. +25 kJ per mole E. 0 kJ per mole
A
Imagine a molecule of free glucose in the blood after a large meal. TRUE or FALSE: ALL of the following things could happen to some or all of its carbons. -Be converted to fructose-2,6-bisphosphate in a liver cell -Become a glycerol backbone in a triglyceride in an adipose cell -Become part of a fatty acid chain in a triglyceride in an adipose cell Be polymerized into glycogen in a skeletal muscle cell -Be phosphorylated and bind allosterically to glycogen synthase A. True B. False
A
Imagine you are a glucose-6-phosphate molecule in a skeletal muscle cell. Which ONE of the following CANNOT happen to you? A. Be dephosphorylated to make glucose B. Be converted to glucose-1-phosphate and incorporated into glycogen C. Be oxidized and enter the pentose phosphate pathway D. All of these things could happen E. Enter glycolysis and become 2 pyruvates that are converted to lactate F. Enter glycolysis and become 2 pyruvates that are converted to acetyl CoA
A
Many reactions discussed in BIOC 405 have used a B-vitamin as a coenzyme to help catalyze reactions of carbohydrate metabolism or mitochondrial respiration. B-vitamins also comprise several energy-carrying molecules. All of the following B-vitamins fall into one of these categories (in bold), except which ONE? A. Vitamin B9 - folate B. Vitamin B3 - niacin C. Vitamin B5 - pantothenic acid D. Vitamin B2 - riboflavin E. Vitamin B6 - pyridoxine F. Vitamin B7 - biotin G. Vitamin B1 - thiamine
A
TRUE or FALSE: Liver cells with a mutant form of fructose-1,6-bisphosphatase that is insensitive to regulation by fructose-2,6-bisphosphate would also have reduced activity of pyruvate kinase. A. True B. False
A
The ______ subunit of the ATP synthase can bind ADP and catalyze synthesis of ATP and the _______ subunit induces conformational changes in that subunit as the F0 portion rotates relative to the F1 subumit. A. beta; gamma B. c; beta C. gamma; delta D. gamma; beta E. alpha; beta.
A
Which ONE has the highest molecular weight? A. FAD B. NAD+ C. FMN D. NMN
A
Which ONE of the following correctly lists the amount of energy needed to make 1 molecule of glucose from 2 molecules of lactate: A. 4 ATP, 2 GTP, 0 NADH B. 4 ATP, 2 UTP, 2 NADH C. 4 ATP, 2 GTP, 2 NADH D. 2 ATP, 2 GTP, 2 NADH E. 2 ATP, 2 GTP, 0 NADH
A
Which ONE of the following statements is NOT correct? A. The electrical potential in this matrix is 150-200 mV more positive than outside the mitochondrion. B. The electrical potential gradient across the mitochondrial inner membrane is as steep as the electrical potential gradient that generates a lighting bolt. C. The pH outside an actively respiring mitochondrion is about 0.75 pH units lower than the pH in the mitochondrial matrix. D. About 10 protons are pumped across the inner mitochondrial membrane for each pair of electrons transferred from NADH to O2.
A
Which one of the choices includes two enzymatic activities that are needed for both photosynthesis and glycolysis? A. Phosphoglycerate kinase and glyceraldehyde-3-phosphate dehydrogenase. B. Glyceraldehyde-3-phosphate dehydrogenase and enolase. C. Transketolase and transaldolase. D. Aldolase and hexokinase.
A
Which one of the following enzymes of the citric acid cycle is an integral membrane protein? A. Succinate dehydrogenase B. Succinyl-CoA synthetase. C. Malate dehydrogenase D. Isocitrate dehydrogenase. E. Citrate synthase.
A
Which one of the following is the acceptor molecule for CO2 in the Rubisco reaction? A. Ribulose 1,5 bisphosphate. B. Ribose-5-phosphate. C. Glyceraldehyde 3 phosphate. D. Erythrose-4-phosphate. E. Pyruvate
A
Which one of the following reactions in the citric acid cycle produces ATP in heart muscle by substrate level phosphorylation? A. Succinyl-CoA synthetase. B. Succinate dehydrogenase. C. Isocitrate dehydrogenase. D. Malate dehydrogenase. E. Citrate synthase.
A
Which one of the following substrates can limit the rate of oxidative phosphorylation? A. Any of these substrates can limit the rate of oxidative phosphorylation depending on metabolic conditions. B. ADP C. O2 D. Succinate E. Pyruvate F. Pi
A
Which one of the following will produce the LEAST amount of ATP per O2 consumed? A. Mitochondria isolated from brown fat. B. Mitochondria isolated from heart. C. Mitochondria isolated from brain. D. Mitochondria isolated from skeletal muscle. E. Mitochondria isolated from liver.
A
all of the following statements about glycogen storage diseases are true EXCEPT A. the pathology is usually associated with the accumulation of too much glycogen in the liver B. in McArdle's disease, the defect is in glycogen phosphorylase C. in McArdle's disease, not enough energy can be supplied by anaerobic glycolysis during vigorous exercise D. in Von Gierke's disease, glucose-6-phosphatase is deficient E. in Von Gierke's disease, patients often suffer from fasting hypoglycemia
A
ferredoxin can carry electrons from PSI to two different places depending on the needs of the cell. which choice best describes the situation in which ferredoxin primarily carries electrons back to cytochrome b6f as part of the cyclic pathway? A. when the cell is absorbing light energy but already has abundant NADPH B. when the cell is in the dark C. when the cell needs both ATP and NADPH synthesis D. when the cell needs NADPH synthesis but already has abundant ATP C. ferredoxin would not carry electrons back to cytochrome b6f in any of these situations
A
of the following ions andd molecules that allosterically regulate enzymes in the citric acid cycle, ONE does not directly reflect the energetic status of the cell. which one? A. Ca2+ B. NADH C. ATP D. ADP E. succinyl-CoA
A
the electron transport chain in the chloroplast pumps protons up a concentration gradient in which direction? A. from the stroma into the thylakoid lumen B. across the inner chloroplast membrane C. from the thylakoid lumen into the stroma D. across the outer chloroplast membrane E. none of the choices
A
which ONE of the following comparisons of the mitochondrial and chloroplast electron transport chains is FALSE? if all of the comparisons are true, choose e. A. int he mitochondrion, the electron transport chain pumps protons out of the matrix, while in the chloroplast it pumps protons out of the thylakoid lumen B. the protonmotive force comprises a chemical and an electrical component in mitochondria, but only a chemical component in chloroplasts C. in mitochondria electron transport takes place on the intermost of two membranes, while in the chloroplasts it takes place on the innermost of three membranes D. both organelles use compartmentation to great effect: in mitochondria the products of the citric acid cycle (ex. NADH) are immediately adjacent to the respiratory chain that uses them, while in chloroplasts ATP and NADPH are produced in the stroma immediately adjacent to the enzymes of the carbon reactions that consume them E. all are true
A
which enzymes involved in bypass reactions in gluconeogenesis are paired correctly with their subcellular location? I. pyruvate carboxylase; mitochondria II. PEPCK; mitochondria III. fructose 1,6 bisphosphatase; cytosol IV. glucose 6 phosphatase; golgi apparatus A. I, III B. I, II, III C. I, III, IV D. II, III E. all are paired correctly
A
which of the following statements about Mg2+ are incorrect? I. durring illumination, Mg2+ is actively transported from the stroma to the thylakoid lumen. II. Mg2+ is the central ion in chlorophyll III. Mg2+ is required for maximal activity of the enzyme that adds CO2 to ribulose-1,5-bisphosphate A. I only B. II only C. III only D. I, II, III E. none, all of the statements are CORRECT
A
which of the following statements about pyruvate carboxylase are TRUE? I. it uses PLP as a prosthetic group to transfer CO2 to the active site II. it can be allosterically activated by acetyl CoA III. it adds a carbon from acetyl-CoA to pyruvate to form oxaloacetate IV. it is present primarily in the cytoplasm A. II only B. I and II C. II and III D. I and III E. I, II, and III
A
which one of the following choices lists the redox pairs in order form most negative to most positive reduction potential? A. NAD+/NADH, FAD/FADH2, ubiquinone/ubiquinol, O2/H2O B. NAD+/NADH, FAD/FADH2, O2/H2O, ubiquinone/ubiquinol C. O2/H2O, ubiquinone/ubiquinol, FAD/FADH2, NAD+/NADH D. O2/H2O, FAD/FADH2, NAD+/NADH, ubiquinone/ubiquinol E. ubiquinone/ubiquinol, NAD+/NADH, FAD/FADH2, O2/H2O
A
which one of the following choices lists the redox pairs in order from most negative to most positive reduction potential? A. alpha-ketoglutarate/isocitrate, NAD+/NADH, ubiquinone/ubiquinol, O2/H2O B. alpha-ketoglutarrate/isocitrate, ubiquinone/ubiquinol, O2/H2O, NAD+/NADH C. O2/H2O, ubiquinone/ubiquinol, FAD/FADH2, NAD+/NADH D. O2/H2O, alpha-ketoglutarrate/isocitrrate, NAD+/NADH, ubiquinone/ubiquinol E. ubiquinone/ubiquinol, NAD+/NADH, FAD/FADH2, O2/H2O
A
which one of the following molecule does not allosterically regulate either pyruvate kinase (PK) or phosphoenolpyruvate carboxykinase (PEPCK)/pyruvate carboxylase (PC)? or do all of these molecules allosterically regulate one or more of these enzymes? A. ribulose-5-phosphate B. ATP C. Acetyl-CoA D. fructose-1,6-bisphosphate E. all of these regulate either PK, PEPCK, or PC
A
pyruvate, oxaloacetate, and citrate are, respectively A. a monocarboxylate, a dicarboxylate, and a tricarboxylate B. a monocarboxylate, a monocarboxylate, and a tricarboxylate C. a dicarboxylate, a dicarboxylate, and a trricarboxylate D. all tricarboxylates
A citrate has added aceytl group onto oxaloacetate --> has 3 carbons now
Which one of the following molecules has the highest molecular weight? A. Alpha-ketoglutarate B. Oxaloacetate C. Isocitrate D. Acetyl CoA E. Citrate
D
Jim, a 19-year-old body builder, was rushed to the hospital emergency room in a coma. he had not eaten for 4 hours and had injected himself with a large dose of insulin about 90 minutes ago, just before beginning what was to be a two-hour workout. all of the following contributed to his hypoglycemic coma EXCEPT A. insulin acts via PP1 to dephosphorylate the PFK2-FBPase 2 bifunctional enzyme B. insulin acts via PP1 to dephosphorylate glycogen synthase C. insulin promotes the movement of Glut44 to the plasma membrane in muscle and adipose tissue D. insulin activates pyruvate dehydrogenase phosphatase to dephosphorylate the pyruvate dehydrogenase enzyme E. all of the answers are correct
A insulin acts via PP1 to dephosphorrylate the PFK-2/FBPase-2 enzyme, activating the kinase domain of hte bifunctional enzyme
you addd three chemicals in the sequence to isolated mitochondria in the presence of oxygen and ADP: pyruvate, then oligomycin, then succinate. which of the following describes the change in the rate of oxygen consumption as each chemical is added? A. increases, decreases, no change B. increases, decreases, increases C. increases, decreases, decreases D. increases, no change, no change
A no change for succinate - you have oligomycin which jams up the entire thing backs up entire ETC, nothing runs
if a cell is exposed to the drug from the last question, roughly how many fewer molecules of ATP will be formed by complete oxidation of 2 pyruvate molecules that enter the TCA cycle? A. 3 ATP B. 4 ATP C. 6 ATP D. 8 ATP
A per pair of e- that goes thru FADH2 = ~1.5 ATP 1.5*2 = 3 ATP complex 1 has NADH but complex 2 is only FADH2
avidin is a protein that binds extremely tightly to biotin, so avidin is a potent inhibitor of biotin-requiring enzyme reactions. consider glucose bio-synthesis from each of the following substrates and predict which of these pathways would be inhibited by avidin. A. lactate B. oxaloacetate C. malate D. fructose-6-phosphate E. phosphoenolpyruvate
A the pathway from lactate to glucose is the only pathway that goes through pyruvate carboxylase in the mitochondria, which requires biotin as a cofactor
a young animal has never had much energy. he is brought to a vet for help and is sent to the animal hospital for some tests. there they discover his mitochondria can use only fatty acids and amino acids for respiration, and his cells produce more lactate than normal. of the following, which is the best explanation of his condition? A. his mitochondria lack the transporrt protein that moves pyruvate across the outer mitochondrial membrane B. his cells cannot move NADH from glycolysis into the mitochondrria C. his cells contain something that inhibits oxygen use in his mitochondria D. his cells lack the enzyme in glycolysis that forms pyruvate E. his cells have a defective electron transport chain, so glucose goes to lactate instead of to acetyl CoA
A without transport of pyruvate into the mitochondria, the reactions catalyzed by the pyruvate dehydrogenase complex and citric acid cycle are unable to metabolize pyruvate. therefore, a buildup of pyruvate leads to more fermentation thru lactate dehydrogenase, and the production of lactate. all other answer choices don't lead to buildup of pyruvate in cytosol and therefore wouldn't directly contribute to an increase in lactate product.
which ONE of the following redox pairs has the MOST NEGATIVE standard reduction potential? A. P700*+ + e- --> P700* B. P680+ + e- --> P680 C. P680*+ + e- --> P680* D. P700+ + e- --> P700
A zigzag scheme - has the most negative reduction potential
beriberi is a disease caused by a thiamine deficiency. which reaction(s) in the pyruvate dehydrogenase complex would be DIRECTLY affected in someone suffering from beriberi? A. decarboxylation of pyruvate B. attaching an acetyl group in lipoamide C. generation of acetyl-CoA D. reforming oxidized lipoamide E. transferring electrons to NAD+
A, B decarboxylation of pyruvate --> TPP cofactor accepts 2 carbons off pyruvate attaching an acetyl group to lipoamide --> TPP also involved in reaction 2
which statemtns about complex IV are true? (choose all that apply) A. this complex catalyzes the reduction of oxygen to water B. despite consuming protons, this complex pumps H+ across the membrane at a rate of 4 per molecule of O2 reduced C. the protons flow across a gradient to the inner membrane space D. conformational changes as electrons flow through the complex alter the ability of some residues to bind protons
A, B, C
Which of the following enzymes catalyze reactions which use inorganic phosphate? (Choose ALL that apply.) A. glycogen phosphorylase B. glycogen synthase C. ATP synthase D. pyruvate carboxylase E. creatine kinase F. pyruvate dehydrogenase G. glyceraldehyde-3-phosphate dehydrogenase
A, C, G
during the investment phase of glycolysis, 2 ATP molecules are consumed. why are those ATP molecules not regeneratedd during gluconeogenesis?
ATP is used to attach phosphate groups to molecules that have a lower phosphoryl transfer energy than ATP (G6P and F-1,6-BP), so these reactions are irreversible. additionally in gluconeogenesis, the phosphate groups can simply be hydrolyzed form G6P and F-1,6-BP in order to be energetically favorable
Which one lists the form of carbohydrate that is used for storage and the form of carbohydrate that is exported to other parts of the plant? A. Amylose, fructose. B. Glycogen, glucose. C. Glucagon, fructose. D. Amylose; sucrose.
D
As described in section 15.3 of the textbook the quantum efficiency for photosynthesis decreases abruptly when the wavelength of light being used becomes longer the 680 nm. Which ONE of the following is the explanation for this "red drop"? A. Photosystem I requires 680 nm light B. The reactions that extract electrons from water to make O2 take place in the photosystem that is activated by 680 nm light. C. Red light inhibits photosynthesis. D. Red light is absorbed by CO2 to initate the synthesis of carbohydrates.
B
How many carbons are there in the hydrophobic tail of the form of Coenzyme Q known as "Q10"? A. 10 B. 50 C. 5 D. 100 E. 1
B
What are the two essential goals of the reactions in the Calvin cycle? A. To make ATP and NADPH. B. To make 6 carbon sugars and to regenerate Ribulose 1,5 bisphosphate. C. To make Ribose 5 phosphate and NADPH. D. To produce CO2 and H2O from glucose.
B
What are the units of the Faraday Constant? A. Joules per meter B. Joules per mole per volt C. Ohms per square centimeter per volt D. Amps per volt E. Coulombs per mole per volt
B
Which ONE has the greatest need for an electron? A. P680 in its excited state (P680*). B. P680 in its electron-deficient state (P680+). C. P700 in its electron-deficient state (P700+). D. P700 in its excited state (P700*).
B
Which ONE of the following enzymes, when activated, would indirectly affect the reaction direction of phosphoglucomutase? A. glucose-6-phosphate dehydrogenase B. all of these C. hexokinase D. glucose-6-phosphatase E. glucokinase
B
Which ONE of the following glycolytic enzymes is NOT used in gluconeogenesis? A. Phosphoglucose isomerase B. Pyruvate kinase C. Enolase D. Aldolase E. Glyceraldehyde-3-phosphate dehydrogenase
B
Which ONE of the following is NOT a pair of molecules that have analogous functions in mitochondria and chloroplasts? A. CF1 and F1. B. Q cycle and light. C. Cytochrome c and plastocyanin. D. Plastoquinone and ubiquinone.
B
Which ONE of the following is not a coenzyme or substrate involved in the pyruvate dehydrogenase complex reaction? A. Coenzyme A B. ATP C. Lipoamide D. Flavin adenine dinucleotide. E. NAD+ F. Thiamine Pyrophosphate.
B
Which ONE of the following statements CORRECTLY describes why glycogenesis requires energy? A. ATP is consumed during isomerization of glucose-6-phosphate to glucose-1-phosphate. B. Regenerating UTP from UDP with nucleoside diphosphate kinase requires ATP. C. Forming (α-1,6) glycosidic linkages from (α-1,4) linkages is not energetically favorable, so ATP hydrolysis provides energy for branching. D. Glycogen synthase uses energy from ATP to add UDP-glucose to the growing glycogen chain. E. The reaction of UDP-glucose-pyrophosphorylase is energetically coupled to ATP hydrolysis.
B
Which ONE of the following statements about glucagon signaling is NOT correct? A. It triggers a phosphorylation cascade that activates glycogen phosphorylase. B. It employs a receptor tyrosine kinase that stimulates adenylate cyclase. C. It occurs using a receptor with 7 transmembrane domains. D. It triggers a phosphorylation cascade that inhibits glycogen synthase. E. It uses cyclic AMP as a second messenger.
B
Which ONE of the following statements about protons and photosynthesis is correct? A. The process of electron transport causes translocation of protons out of the chloroplast across the chloroplast inner and outer membrane into the cytoplasm of the cell. B. The process of electron transport concentrates protons in the thylakoid lumen. C. The process of electron transport does not cause translocation of protons. D. The process of electron transport concentrates protons in the stroma.
B
Which ONE of the following statements is INCORRECT? A. The so-called "dark-reactions" are accelerated by light. B. Photosynthesis in plants occurs in two stages. The first uses water to reduce CO2 to carbohydrates. The second uses NADPH to convert ADP into ATP. C. Some organisms use hydrogen gas instead of water as a reducing agent. D. Both atoms of oxygen in the O2 produced by photosynthesis come from water.
B
Which one of the following does NOT describe a way that photosynthesis is regulated? A. Light raises the pH in the stroma, which stimulates Rubisco activity. B. Light stimulates phosphofructokinase and glucose-6-phosphate dehydrogenase. C. Light stimulates reduction of thioredoxin which reduces and activates several enzymes in the Calvin Cycle. D. Light causes the concentration of Mg2+ to increase in the stroma, which stimulates Rubisco activity.
B
Which one of the following enzymes is most similar to pyruvate dehydrogenase? A. malate dehydrogenase. B. Isocitrate dehydrogenase. C. Succinate dehydrogenase. D. a-ketoglutarate dehydrogenase.
D
Which version of the pentose phosphate pathway will generate the most NADPH? A. The one in which GAP is used to make pyruvate. B. The one in which GAP and F6P are used to regenerate Glucose-6-phosphate. C. The one in which Ribose-5-phosphate is used to make nucleotides. D. The one in which ribose-5-phosphate is made into ribulose 1,5 bisphosphate.
B
You make dilute 1 nM solutions each of glycogen, amylose and amylopectin in water, fully solubilizing the polysaccharide molecules in a test tube. You then add a reagent to each tube that is nonfluorescent when free in solution, but reacts irreversibly with polysaccharide non-reducing ends to introduce a covalently-bound fluorescent tag. After the reagent is allowed to react completely with the polysaccharide in each tube, rank the resulting polysaccharide solutions based on fluorescence: less fluorescent < ... < more fluorescent A. amylopectin < amylose < glycogen B. amylose < amylopectin < glycogen C. glycogen < amylopectin < amylose D. all solutions would have the same fluorescence E. glycogen < amylose < amylopectin
B
choose the corerct set of words to fill in the blanks. glycogen phosphorylase and ___________ both produce phosphorylated products by ____________. A. pyruvate kinase; coupling their reactions to ATP hydrolysis B. GAPDH; directly incorporating Pi by phosphorolysis C. GAPDH; coupling their reactions to ATP hydrolysis D. hexokinase; directly incorporating Pi by phosphorolysis E. hexokinase; coupling their reactions to ATP hydrolysis
B
cytochrome c (cyt c) differs from ubiquinone (Q) in that: A. cyt c carries one electron and is a small molecule whereas Q caries one or two electrons and is a protein B. cyt c carries one electron and is a protein whereas Q carries one or two electrons and is a small molecule C. cyt c caries one or two electrons and is a small molecule whereas Q carries one electron and is a protein D. cyt c carries one or two electrons and is a protein whereas Q carries one and is a small molecule
B
how many molecules of CO2 does a plant cell fix into carbohydrate to make one molecule of sucrose? A. 15 B. 12 C. 6 D. 5 E. 3
B
the pyruvate dehydrogenase and alpha-ketoglutarate dehydrogenase reactions are catalyzed by large, multi-subunit complexes that are overall quite similar. howeve,r some of the subunits of these complexes are different proteins, while others are in fact identical. which subunit(s) is/are different between the two complexes? A. E1 only B. E1 and E2 C. E1 and E3 D. E2 only E. E2 and E3
B
which one of the following choices lists a monocarboxylate, dicarboxylate, and tricarboxylate in that order? A. acetate, pyruvate, citrate B. pyruvate, malate, citrate C. citrate, isocitrate, alpha-ketoglutarate D. isocitrate, citrate, pyruvate E. malate, succinate, fumarate
B
Mn2+ is an important nutrient for plants. Yellowing between the veins of new leaves is a symptom of Mn2+-deficiency. Which process in photosynthesis is directly affected by this deficiency? A. harvesting photons and getting them to the special pair in PSII B. resupplying an electron to P680+ in PSII C. pumping protons in cytochrome b6f D. transferring electrons from cytochrome b6f to PSI E. excitation of P700 in PSI
B A would be magnesium
which one "wants" electrons more than any of the others? A. NADP+ B. P680+ C. P700+ D. P680*+ E. P700*+
B P680*+ does not care about electrons
high levels of glucagon in the blood leads to: A. increased PKA activity, increased glycogenesis B. increased PKA activity, increased glycogenolysis C. decreased PKA activity, increased glycogenesis D. decreased PKA activity, increased glycogenolysis
B adenylate cyclase, cyclic AMP pathway --> leads to glycogenolysis --> breakdown of glucagon, mobilization of glucose glucagon is what causes body to break down glucose and mobilize more glycogen
use the following figure and the stages labeled A, B, C, D, and E to answer the following questions. if the carbon atom of the incoming CO2 molecule is labeled with a radioactive isotope of carbon, where will the radioactivity be measurable after one cycle? see image in post lecture 25 A. in C only B. in E only C. in C, D, and E D. in A, B, and C E. in B and C
B after one cycle, the carbon will have been successfully incorporated into ribulose bisphosphate, and therefore would be radioactively traced at step E
given a healthy individual with a normal metabolic rate, which of the following compounds is the most energy rich? A. GTP B. NADH C. FADH2 D. ATP
B both GTP and ATP are energetically equivalent, each yielding 1 ATP. Oxidation of 1 FADH2 in the ETC yields 1.5 ATP. Oxidation of 1 NADH in the ETC yields 2.5 ATP (due to extra pumping of e- at complex I)
you have a drug that decreases the energy production of cellular respiration and you know it inhibits some part of the electron transport chain. however, when a test tube with purified mitochondrial membranes and their cofactors is given abundant NADH, O2 and your drug, you find that O2 is still being reduced with minimal loss of activity upon drug treatment. which complex is your drug inhibiting? A. complex I B. complex II C. complex III D. complex IV
B complex II accepts e- from succinate not from NADH
when insulin activates protein phosphatase, then protein phosphatase does all of the following EXCEPT A. activates glycogen synthase by dephosphorylation B. activates phosphorylase kinase by dephosphorylation C. inactivates glycogen phosphorylase by dephosphorylation D. activates pyruvate kinase by dephosphorylation
B insulin vs. glucagon protein phosphatase exerts action through dephosphorylation, and insulin promotes anabolic pathways (glycogenesis) and glycolysis. therefore, insulin would activate glycogen synthase and pyruvate kinase, and inactivate glycogen phosphorylase. phosphorylase kinase would ultimately activate glycogen phosphorylase, so it wouldn't make sense that insulin would activate it. thus, B is the odd one out, and the incorrect statement.
given the table of standard reduction potentials for the half reactions below, what is the change in standard reduction potential for reaction 3 in the TCA cycle (isocitrate dehydrogenase)? table in pollev 21 A. 0.11 B. 0.06 C. -0.06 D. 0.41
B relevant half reactions: -alpha-ketoglutarate --> isocitrate -NAD+ --> NADH pulling e- out of isocitrate and putting them onto NAD+ to form NADH therefore -0.32 + 0.38 = 0.06
Which one of the following intermediates of the citric acid cycle is least abundant in mitochondria? A. citrate B. Alpha-ketoglutarate. C. Malate D. Oxaloacetate E. Succinate
D
which of the following statements about regulation of the Calvin cycle is incorrect? A. the major enzymes that are regulated include Rubisco, fructose bisphosphatase, sedoheptulose bisphosphatase, and phospho-ribulokinase B. the light reactions pump H+ out of the lumen, raising the pH of the stroma, dissipating the electrochemical gradient and activating Rubisco C. through thioredoxin, a photon of light activates the bisphosphatase enzyme D. rubisco activase is allosterically activated by Fd and inhibited by Ca1P
B the light reactions pump H+ out of the stroma, raising the pH of the stroma, which activates the rubisco enzyme no electrochemical gradient between the storma and the lumen in chloroplasts due to Mg2+ being pumped from the lumen to the stroma
you add threre chemicals in a sequence to isolated mitochondria in the presence of oxygen, ADP: pyrruvate, then oligomycin, then DNP. which of the following describes hte change in the rate of oxygen consumption as each chemical is added? A. increases, decreases, no change B. increases, decreases, increases C. increases, decreases, decreases D. increases, no change, no change
B when you add DNP, its an uncoupler ETC goes nuts not making ATP, but ETC can run
the number of subunits in the c ring varies across different species. what would you expect to be an effect of having a larger number of subunits in the c ring, all else being equal? A. more ATPs would be synthesized per pair of electrons that goes through the electron transport chain B. fewer ATPs would be synthesized per pair of electrons that goes through the electron transport chain C. each 3 subunits you add to the c ring would generate an additional ATP per pair of electrons that goes through the electron transport chain D. each 3 subunits you add to the c ring would generate one fewer ATP per pair of electrons that goes through the electron transport chain
B you get 3 ATPs per 360 deg rotation if you add more subunits - dividing 360 deg into more slices takes more protons to make each 360 deg turn have to transport more e- to get same 360 deg rotation
which of the following are mechanisms we discussed by which electrons stored in cytoplasmic NADH can reach the electron transport chain? A. NADH crosses the inner mitochondrial membrane through an NADH transporter B. the electrons are transferred to malate, which is then imported into the mitochondrial matrix and re-oxidized C. the electrons are transferred to FADH2 in membrane proteins, despite a loss in ultimate energy production D. transmembrane oxidorerductases transfer electrons more or less directly from cytosolic NADH to mitochondrial NAD+
B, C
which of the following classes of enzymes are used in the pentose phosphate pathway but NOT the Calvin cycle? A. isomerase B. transaldolase C. transketolase D. dehydrogenase E. lactonase F. all of the above
B, E
which of the following enzymes are NOT correctly paired with their coenzyme(s)? A. pyruvate dehydogenase (E1) and thiamine pyrophosphate B. pyruvate dehydrogenase (E1) and lipoic acid C. dihydrolipoamide transacetylase (E2) and lipoic acid and coeznyme A D. dihydrolipoamide dehydrogenase (E3) and FAD and NAD+ E. dihydrolipoamie dehydrogenase (E3) and lipoic acid
B, E lipoic is attached to E2 only a cofactor for E2, but involved in reaction with E1 and E3
Choose the correct pair of words to fill in the blank: During prolonged exercise, ________ from skeletal muscle enters the blood and is used by the liver for ___________. A. Pyruvate, gluconeogenesis B. ADP, gluconeogenesis C. Lactate, gluconeogenesis D. Lactate, glycogenesis E. Pyruvate, glycogenesis
C
FCCP is a molecule that uncouples electron transport from ATP synthesis by binding protons in the mitochondrial intermembrane space and releasing them in the matrix. choose the observation that is most consistent with the property of FCCP when pyruvate, O2, and ADP are added to isolated mitochondria in the presence of FCCP. A. nothing happens B. ATP synthesis proceeds normally C. O2 is consumed but little to no ATP is made D. ATP synthesis proceeds faster than in the absence of FCCP E. the pH gradient across the inner mitochondrial membrane is greater than in the absence of FCCP
C
In the respiratory cascade there are two steps where electrons must be carried from one respiratory complex to another respiratory complex. Which ONE of the following choices lists 1) a lipid soluble electron carrier and 2) a water soluble electron carrier that each carry electrons from one respiratory complex to another? A. 1) NADH; 2) Cytochrome C B. 1) Cytochrome C; 2) Iron Sulfur protein C. 1) Coenzyme Q; 2)Cytochrome C D. 1) Iron Sulfur protein; 2) Coenzyme Q E. 1) NADH; 2) FADH2
C
When Acetyl CoA reacts with oxaloacetate in the Citrate Synthase reaction, how many carbons are in the product that is formed, citrate? A. 5 B. 20 C. 6 D. 4
C
Which ONE best describes the sequence of events that occur in Complex I? A. Oxidation of NADH to NAD+; Reduction of Cyt box to Cyt bred; Reduction of O2 to H2O. B. Oxidation of Succinate to Fumarate; Reduction of Cyt box to Cyt bred; Reduction of O2 to H2O. C. Oxidation of NADH to NAD+; Reduction of FMN to FMNH2; Reduction of Fe3+ to Fe2+; Reduction of CoQ to CoQH2. D. Oxidation of NADH to NAD+; Reduction of Cyt cox to Cyt cred; Reduction of CoQ to CoQH2; Reduction of Fe3+ to Fe2+.
C
Which ONE of the following enzymes DOES NOT receive either feed-forward activation or feedback inhibition? A. FBPase-1 B. Pyruvate kinase C. Glucose-6-phosphatase D. PFK-1 E. PFK-2/FBPase-2
C
Which ONE of the following enzymes uses ATP during gluconeogenesis? A. Glyceraldehyde-3-phosphate dehydrogenase B. Enolase C. Phosphoglycerate kinase D. Aldolase E. Phosphoglycerate mutase
C
Which ONE would make the most ATP per O2 reduced (highest P/O ratio)? A. Mitochondria incubated with succinate and dinotrophenol. B. Mitochondria incubated with pyruvate and dinotrophenol. C. Mitochondria incubated with pyruvate. D Mitochondria incubated with succinate.
C
Which one of the following inhibits many steps in the citric acid cycle? A. ADP B. insulin C. NADH D. Ca2+
C
Which one of the following lists the two primary functions of the pentose phosphate pathway? A. To use NADPH and ATP to convert CO2 into sugars; to produce O2. B. To use NADPH and ATP to convert CO2 into sugars; to produce O2. C. To produce NADPH to support biosynthetic reactions; to produce ribose-5-phosphate for nucleotide and nucleic acid biosynthesis. D. To produce ATP; to regenerate NAD+. E. To generate ribose-5-phosphate for nucleotide synthesis; to regenerate NAD+.
C
Which one of the following statements is correct? A. Only one of the two carbons that enter the citric acid cycle as acetyl CoA is removed as CO2 in the first round of the citric acid cycle. B. Both of the carbons that enter the citric acid cycle as acetyl CoA are removed as CO2 in the first round of the citric acid cycle. C. Neither of the two carbons that enter the citric acid cycle as acetyl CoA are removed as CO2 in the first round of citric acid cycle.
C
Why does a vitamin B6 deficiency impair glycogenolysis? A. The PLP derived from vitamin B6 is an electron donor for the glycogen phosphorylase reaction. B. The PLP derived from vitamin B6 is needed for glycogen phosphorylase to stabilize ATP during phosphate transfer. C. The PLP derived from vitamin B6 is covalently attached to glycogen phosphorylase and transfers a phosphate to the substrate. D. The PLP derived from vitamin B6 keeps inhibitors from entering the active site of glycogen phosphorylase. E. The PLP derived from vitamin B6 helps glycogen phosphorylase form a Schiff base linkage with the substrate.
C
at the center of each glycogen molecule is a dimer of which protein? A. glycogen synthase B. glycogen phosphorylase C. glycogenin D. branching enzyme E. debranching enzyme
C
choose the correct set of words to fill in the blanks. the function of uncoupling protein 1 in cells like brown adipose tissue leads to _____________. as a result, ablation (removal) of uncoupling protein 1, in addition to causing dysregulation of body temperature, also causes __________. A. increased H+ flux through ATP synthase; weight loss B. increased H+ flux through ATP synthase; obesity C. the generation of less ATP for anabolic reactions; obesity D. the generation of less ATP for anabolic reactions; weight loss E. increased sensitivity to oligomycin; mitochondrial damage
C
choose the correct set of words to fill in the blanks. the thiazolium ring of TPP serves as a(n) ____________ that can stabilize intermediates in __________ reactions. A. reducing agent; redox B. oxidizing agent; redox C. electron sink; decarboxylation D. phosphate donor; substrate-level phosphorylation E. electron donor; glycolytic
C
inhibiting which enzyme would disrupt a major role of both gluconeogenesis and glycogenolysis in the liver? A. phosphoglucomutase B. pyruvate kinase C. glucose-6-phosphatase D. hexokinase
C
succinate modulates the level of hypoxia-inducible factor (HIF-1) by competitively inhibiting HIF prolyl hydroxylase, the enzyme that targets HIF-1 for degradation. Deactivating mutations in which enzyme would likely result in increased levels of HIF-1? A. pyruvate kinase B. citrate synthase C. succinate dehydrogenase D. pyruvate carboxylase
C
the citric acid cycle is regulated by multiple mechanisms, including substrate availability. the concentration of which ONE of the substrates in the mitochondrion is an important parameter for controlling flux through the citric acid cycle? if none of the substrates given are correct, choose that answer. A. fumarate B. glyceraldehyde-3-phosphate C. acetyl-CoA D. isocitrate E. none of the other choices are correct
C
the pentose phosphate pathway and the Calvin cycle share many similar concepts and types of enzymatic reactions. Yet one of the main outputs of the pentose phosphate pathway is the same as the light reactions of photosynthesis, which feed the Calvin cycle. which output? A. R5P B. ATP C. NADPH D. NADH E. Mg2+
C
what would you expect to be an indirect consequence of the mutation in the gamma subunit from the last question? A. ATP synthesis would be enhanced B. ATP synthesis would be unchanged C. ATP synthesis would be uncoupled from electron transport D. ATP synthesis would remain tightly coupled to electron transport
C
Which one of the following is the part of the citrate synthase reaction that is most exergonic and provides the driving force for the reaction? A. Proton transfers. B. Formation of a new C-C bond. C. Rearrangement of the pro-chiral center from pro-R to pro-S. D. Thioester hydrolysis.
D
which ONE of the following statements correctly describes the final products of photosynthesis and where they are synthesized? A. sucrose is made in the stroma and starch is made in the cytoplasm B. glucose is made in the stroma and starch is made in the thylakoid lumen C. starch is made in the stroma and sucrose is made in the cytoplasm D. glycogen is made in the stroma and glucose is made in the cytoplasm E. both sucrose and starch are made in the stroma
C
which choice best descrribes what provides the driving force to synthesize UDP-glucose from UTP and glucose-1-phosphate? A. the energy that was added during the glucophosphomutase reaction B. hydrolysis of uridine from the final product C. hydrolysis of the pyrophosphate product D. formation of a new anhydride bond E. formation of alpha(1-->6) branches by the branching enzyme
C
which correctly maps the movement of electrons through E3? A. NAD+, FAD, E3 disulfide, dihydrolipoic acid B. FAD, NAD+. E3 disulfide, dihydrolipoic acid C. Dihydrolipoic acid, E3 disulfide, NAD+, FAD D. ddihydrolipoic acid, E3 disulfide, FAD, NAD+ E. NAD+, dihydrolipoic acid, E3 disulfide, FAD
C
which enzyme catalyzes a gluconeogenic reaction that is an anapleurotic reaction? A. fructose-1,6-bisphosphatase B. glucose-6-phosphatase C. pyruvate carboxylase D. phosphoenolpyruvate carboxykinase E. triose phosphate isomerase
C
which of the following is the source of the electrons that enter the photosynthetic electron transport chain? A. NADH B. Glucose C. H2O D. O2 E. Q
C
which of the following lists all product(s) of the pyruvate dehydrogenase complex? A. acetyl CoA and NADH B. acetyl CoA and FADH2 C. acetyl CoA, NADH, and CO2 D. acetyl CoA, FADH2, and CO2 E. acetyl CoA
C
which of the following statements about regulation of calvin cycle enzymes is correct? A. all of the regulated reactions use ATP as a substrate B. all of the regulated reactions transfer carbon units between sugar phosphates C. all of the regulated reactions are essentially irreversible D. all of the regulated reactions are in the regeneration phase
C
which one of the following choices lists two electron carriers or electron transfer centers that act as "two to one" converters (i.e. they carry two electrons and transfer them one at a time)? A. NADH2 and FADH2 B. FADH2 and FeS clusters C. FADH2 and coenzyme Q (ubiquinol) D. NADH and FeS clusters E. coenzyme Q and hemes
C
which type of molecule is part of the photosynthetic electron transport chain but not the mitochondrial electron transport chain? A. FeS clusters B. hemes C. chlorophylls D. quinones E. thiamine pyrophosphate (TPP)
C
many more photons are absorbed than can be passed onto the special pair. what happens to the energy from all the other photons? A. it is emitted as ultraviolet fluorescence B. it causes electrons to be released which then reduce O2 to superoxide anions C. it is emitted as infrared fluorescence D. it resonates between antenna pigments fo as long as it takes a special pair to become available
C A - can't come out as ultraviolet fluorescence --> if light is 700 or 680 nm light, it's not UV (UV is higher energy) B - plants have lots of mechanisms to protect themselves from oxidative damage D - lifetime of excited state is very short
which of the following best describes the mechanisms of energy production by the citric acid cycle? energy is produced in the forms of: A. ATP, which directly supplies energy for many cellular processes, and NAD+ which supplies electrons to the electron transport chain B. NAD+ which directly supplies energy for many cellular processes, and ATP, which supplies electrorns to the electron transport chain C. ATP, which directly supplies energy for many cellular processes, and NADH, which supplies electrons to the electron transport chain D. NADH which directly supplies energy for many cellular processes, and ATP, which supplies electrons to the electron transport chain
C ATP - direct energy through phosphoryl transfer NADH - stores e-
a biopsy is done on a child with an enlarged liver and shows accumulation of glycogen granules terminating in single glucose residues with alpha(1-->6) linkages. there is most likely a genetic defect in the gene encoding: A. glycogen phosphorylase B. branching enzyme C. debranching enzyme D. phosphoglucose mutase
C alpha 1-6 activity exists in debranching enzyme if you can't chop off alpha 1,6 - you get an accumulation of glycogen
a bioinformaticist studying the gene encoding the c-ring of ATP synthase notices that one glutamate in the protein is particularly highly conserved, tolerating only a single amino acid other than the wild-type. which amino acid is tolerated? A. alanine B. gluatmine C. aspartate D. lysine
C both negatively charged amino acids with carboxylate group
which two complexes have the MOST simlar types of biochemical activities? A. respiratory complex I and cytochrome b6f B. respiratory complex IV and photosystem I C. respiratory complex III and cytofhrome b6f D. respiratory complex I, and photosystem I E. respiratory IV and photosystem II
C both run Q cycle, both take up Q or plastiquinone, both give up e- to either plastocyanin or cytochrome c
how many NTPs would a plant cell consume during the Calvin cycle to convert carbon dioxide into 1 molecule of sucrose? A. 27 B. 30 C 36 D. 42
C carbon dioxide is 1 carbon, sucrose is 12 we burned 9 ATPs and a bunch of NADPHs as well during Calvin Cycle to convert 3 CO2 to GAP we pulled off 1 GAP (3 carbon) sucrose has 12 carbons 9x4 = 36 ATPs
what would the most direct effect of a harmful mutation in the gamma subunit of ATP synthase that ablated its interactions with the alpha/beta subunits? assume no other part of the complex is affected A. protons could not bind to ATP synthase B. prrotons could not be released from ATP synthase C. the gamma subunit would spin freely inside the alpha/beta trimer D. oligomycin would not longer prevent rotation of the c-ring
C gamma - spins inside catalytic subunits if catalytic subunits are not binding subunits and catalyzing reaction, not gonna let gamma spin either but if you mutate gamma so its not connected to alpha/beta, it's now just spinning
a cell completely oxidizes glucose-6-phosphate to CO2 in the cytoplasm by cycling the carbons repeatedly through the pentose phosphate pathway. the cell did this because it needed A. ATP B. electrons for the mitochondrial electrons transport chain C. reducing equivalents for anabolic reactions D. lactate E. a cold one
C not B - it is electrons but not e- for mitochondrial electron transport chain, that's what citric acid cycle is doing
high levels of ATP, NADH, and acetyl CoA are found in a cell at a given time point. subsequently, the cell is exposed to very strong competitive inhibitors of PDDH kinase and PDH phosphatase. after exposure to the inhibitorrs, which form predominates? A. non-phosphorylated PDH B. non-phosphorylated PDH at first, then phosphporylated PDH after a while C. phosphorylated PDH D. none of the above
C phosphorylated PDH --> PDH complex slide --> if we have high levels of energy rich compounds (right) - generates phosphorylated --> if you freeze, you freeze in phosphorylated state, can't become dephosphorylated because you froze phosphorylated
which ONE of the following is INCORRECT about the oxygen evolving complex? A. it contains a Mn2+ ion B. it transfers electrons to oxidized P680 in its ground state C. it releases 4 protons into the stroma D. it makes O2 from the O atoms from 2 H2O
C releases into the lumen
how many ATPs would a cell net from the complete oxidation of a glucose molecule that is first stored in glycogen (prior to oxidation)? consider all the steps from blood glucose to ATP synthase. A. 28 B. 30 C. 31 D. 32 E. 33
C starting from blood glucose to ATP synthase lose 1 ATP, 31 total
Fill in the blanks. The _______ generates more __________ at the expense of ________ when the plant cell has an abundance of reducing power A. noncyclic pathway; ATP; NADPH B. cyclic pathway; NADPH; ATP C. cyclic pathway; ATP; NADPH D. transfer of electrons from NADPH back to PSII; ATP; NADPH E. transfer of electrons from Fd to NADP+; NADPH; ATP
C when you have enough NADPH, you get cyclic pathway so e- go back through back to cytochrome b6f and Q cycle --> generate more proton gradients and more ATP
Which ONE has the lowest need for an electron? A. P680 in its excited state (P680*). B. P700 in its electron-deficient state (P700+). C. P680 in its electron-deficient state (P680+). D. P700 in its excited state (P700*).
D
Which ONE is the part of a chloroplast that absorbs the light used to power photosynthesis? A. Chloroplast outer membrane. B. Chloroplast inner membrane. C. Stroma D. Thylakoid membrane.
D
Which ONE of the following describes how energy is transferred from antenna molecules to chlorophyll in the reaction center? A. Electron transfer. B. Emission of fluorescence that is absorbed by the chlorophyll in the reaction center. C. Breaking a chemical bond and forming a new one. D. Resonance transfer.
D
Which ONE of the following does not transfer electrons to CoQ to make CoQH2? A. Glycerol-3-phosphate dehydrogenase. B. Complex II. C. Complex I. D. Complex IV.
D
Which ONE of the following provides a long arm that can swing a substrate from one site to another in the PDH complex? A. NAD+ B. Coenzyme A C. Thiamine Pyrophosphate D. Lipoamide E. Flavin adenine dinucleotide F. ATP
D
Which ONE of the following respiratory complexes does not pump protons across the mitochondrial inner membrane when it is actively transferring electrons from its substrate to its product? A. Complex I. B. Complex III C Complex IV. D. Complex II.
D
choose the correct set of words to fill in the blanks. the two main carbon-shuffling enzymes in the pentose phosphate pathway are transketolase and transaldolase. transketolase uses _____ as a cofactor, while transaldolase uses _________. A. PLP, TPP B. PLP; a lysine side chain to form a Schiff base C. FAD; NADH D. TPP; a lysine side chain to form a Schiff base E. TPP; NADH
D
in a normally functioning mitochondrion, each complete rotation of the c-ring of ATP synthase results in the formation of how many ATP molecules? A. 0 B. 1 C. 2 D. 3 E. 4
D
in which of the following physiological scenarios is the rate of gluconeogenesis in the body likely at a maximum? A. glucagon release is inhibited B. high levels of insulin are being secreted C. low stores of protein in the body D. low stores of glycogen in the body E. high levels of sugar in the blood
D
oligomycin is an antibiotic that binds and inhibits ATP synthase, yet also inhibits the electron transport chain. choose the answer that best accounts for this observation. A. oligomycin also directly binds to complex III B. oligomycin binding drives a conformational change in ATP synthase that allosterically regulates complex IV C. oligomycin directly competes with ADP binding in the ATP synthase active site D. by blocking the flow of protons back into the mitochondrial matrix, oligomycin makes the thermodynamic cost of proton transport to a halt. E. oligomycin dissipates the proton gradient by itself transporting protons across the inner mitochondrial membrane
D
when you first wake up in the morning (before you break your fast), PFK-2/FBPase-2 will be _________, causing higher ________ activity A. more dephosphorylated; PFK-2 B. more dephosphorrylated; FBPase-2 C. more phosphorylated; PFK-2 D. more phosphorylated; FBPase-2
D
which ONE of the following enzymes catalyzes a decarboxylation reaction in the pentose phosphate pathway? A. Rubisco B. transketolase C. transaldolase D. 6-phospho-gluconate dehydrogenase E. glucose-6-phosphate dehydrogenase
D
which of the following reactions does NOT store electrons in NADH? if all the listed reactions store electrons in NADH, choose that answer. A. alpha-ketoglutarate dehydrogenase B. isocitrate dehyddrogenase C. malate dehydrogenase D. succinate dehydrogenase E. all of the other reactions store electrons in NADH
D
which of the following statements about the pyruvate dehydrogenase complex are INCORRECT? I. the pyruvate dehydrogenase complex is located in the cytoplasm II. the reaction catalyzed by pyruvate dehydrogenase is highly exergonic III. the pyruvate dehydrogenase complex is regulated allosterically, by reversible phosphorylation, and transcriptionally IV. all four required cofactors bind and dissociate from pyruvate dehydrogenase complex during the course of the reaction V. pyruvate dehydrogenase is an example of an enzyme complex that allows direct channeling of reaction intermediates from one enzyme active site to the next A. I and II B. II and III C. IV and V D. I and IV E. I and V
D
which one of the following enzymes is NOT paired with its correct cofactor? some of the enzymes may have more cofactors in addition to the one listed. A. pyruvate dehydrogenase (E1) // thiamine pyrophosphate (TPP) B. photosystem II // oxygen-evolving complex (OEC) C. glycogen phosphorylase // pyridoxal-5-phosphate (PLP) D. succinate dehydrogenase // NAD+ E. alpha-ketoglutarate dehydrogenase // thiamine pyrophosphate (TPP)
D
which one of the following statements about gluconeogenesis is FALSE? A. most of the gluconeogenesis in our bodies occurs in the liver B. gluconeogesis occurs primarily under fasting or starving conditions C. most of the energy to synthesize glucose by gluconeogenesis comes from fatty acid oxidation D. gluconeogenesis is not regulated by hormones E. PEP carboxykinase transfers a phosphate from GTP and it decarboxylates the substrate when it forms PEP from oxaloacetate
D
which one of the following statements about the F1F0 ATP synthase is incorrect? A. a proton concentration gradient is highest in the intermembrane space and lowest in the matrix provides the energy to dive the synthesis of ATP B. the c subunits bind and release protons C. the gamma subunit alters the conformation of the beta subunits as it rotates D. newly synthesized ATP is released from the beta subunits directly into the intermembrane space E. rotation within the ATP synthase is blocked by oligomycin
D
which two of the following catalytic activities involved in the glycogen metabolism are found in a single enzyme? I. mutase II. transferase III. phosphorylase IV. alpha-1,6-glucosidase A. I and II B. I and III C. II and III D. II and IV E. III and IV
D
andersen's disease (glycogen storage disease type IV) is a condition characterized by a deficiency in glycogen branching enzyme. absence of this enzyme would be likely to cause ALL of the following EXCEPT: A. a higher proportion of G1P compared to glucose released upon glycogenolysis B. slower overall glycogenolysis by glycogen phosphorylase C. less glycogen storage in the body overall D. glycogen lacking alpha (1-->4) linkages
D A would cause - glucose-1-phosphate comes from T-rex --> chops off linear 1,4 linkages B would also cause - branching introduces more non-reducing ends --> quicker mobilization of glucose C would cause - branching also makes glycogen more compact --> dense granules of glucose
alanine can be converted to a pyruvate in a single transaminase reaction. if cells were only given alanine as an energy source, how many ATPs could they generate from 1 mole of alanine? A. 32 ATP B. 30 ATP C. 25 ATP D. 12.5 ATP
D alanine coming from proteins that can be converted in a single step to pyruvate --> miss all of glycolysis 2 moles pyruvate per 1 mole glucose 25/2 = 12.5 ATP
which answer matches the correct enzyme for each reaction? I. 3C + 7C -> 6C + 4C II. 5C + 4C -> 3C + 6C III. 3C + 4C -> 7C A. I: transketolase, II: transaldolase, III: aldolase B. I: aldolase, II: transketolase, III: aldolase C. I: transketolase, II: transaldolase, III: transaldolase D. I: transaldolase, II: transketolase, III alddolase
D aldolase should be the last one --> combining or breaking apart diff sugars transketolase transfers 2 carbons at the same time --> must be II
only one of the following citric acid cycle intermediates contains 2 carbons linked by a double bond. which one? A. succinate B. isocitrate C. malate D. alpha-ketoglutarate E. fumarate
E
in the liver, glucose-6-phosphate is readily converted to all of the following EXCEPT A. glucose by glucose-6-phosphatase B. glucose-1-phosphate by phosphoglucomutase C. fructose-6-phosphate by phosphoglucose isomerase D. UDP-glucose by UDP=glucose pyrophosphorylase E. 6-phospho-gluconolactone by glucose-6-phosphate dehydrogenase
D glucose-6-phosphate is a central intermediary in carbohydrate metabolism. gluocse-6-phosphatase is expressed primarily in the liver and kidney and converts G6P to glucose. however, in glycogen synthesis, UDP glucose pyrophosphorylase attaches a UMP group to gluocse-1-phosphate rather than glucose-6-phosphate. glucose-6-phosphate must undergo isomerization to glucose-1-phosphate
if all energy (100%) from each redox reaction (ie electron transport) were somehow converted to proton pumping, given the rerduction potentials below, which complex would pump the most protons out of the mitochondrial matrix? see pollev 21 A. complex I B. complex II C. complex III D. complex IV
D going further downhill bc O2 has such a high reduction potential
all of the following will result in activation of glycogen phosphorylase in skeletal muscle EXCEPT A. increased concentrations of AMP from contraction of muscle B. increased epinephrine and cAMP C. increased cystolic [Ca2+] D. increased protein phosphatase E. increased activity of phosphorylase kinase
D protein phosphatase (activated by insulin signaling) will dephosphorylate and inactivate glycogen and phosphorylase kinase, thus inactivating glycogen phosphorylase in the long run. all the other metabolites contribute to the activation of glycogen phosphorylase. Ca2+ activates the kinase that converts phosphorylase b to phsophorylase a
how many additional nucleoside triphosphates (after the Calvin cycle) are required to complete the synthesis of sucrose? A. 4 B. 3 C. 2 D. 1
D single UTP diagram of making amylose or sucrose
which enzyme catalyzes a reaction that produces NADH, but not carbon dioxide (CO2)? A. isocitrate dehydrogenase B. alpha-ketoglutarate dehydrogenase C. fumarase D. malate dehydrogenase
D top 2 are steps 3 and 4 fumarase is not doing redox (extracting e-)
select all of the following electron carriers that carrry only a single electron? A. NADH B. Flavins C. coenzyme Q D. cytochromes E. Fe-S clusterrs F. copper
D, E, F NADH - 2 e- in form of hydride flavins and coenzyme Q - can do either 1 or two
How many ATP and how many NADH molecules are invested to add one molecule of glucose to a glycogen chain? A. 1 ATP, 0 NADH B. 1 ATP, 1 NADH C. 0 ATP, 0 NADH D. 2 ATP, 1 NADH E. 2 ATP, 1 NADH
E
Which ONE of the following statements about PFK-2/FBPase-2 is FALSE? A. It is expressed only in liver cells. B. FBPase-2 is inhibited by fructose-6-phosphate as a form of negative feedback inhibition. C. It is phosphorylated by PKA, which activates the phosphatase domain. D. In the fed state it is dephosphorylated, and the kinase domain is active. E. PFK-2 is activated by fructose-2,6-bisphosphate as a form of feed-forward stimulation.
E
Which of the following fill-in-the-blank statements is FALSE? (Choose ONE.) In the fed state, there is more glycogen in than in by wet weight. A. 1 g liver tissue, 1 g brain tissue B. all of the body's skeletal muscle tissue, all of the body's liver tissue C. 1 g liver tissue, 1 g skeletal muscle tissue D. 1 g skeletal muscle tissue, 1 g adipose tissue E. all of the body's brain tissue, all of the body's liver tissue
E
after fasting for many hours, glycogen stores run low. certain cell types, such as neurons and red blood cells, still require glucose as an energy source. which one of the following molecules CANNOT be used as gluconeogenic precursor? A. alanine B. glycerol C. oxaloacetate D. lactate E. CO2
E
all of the following statements about the pentose phosphate pathway are true EXCEPT A. its two functions are to produce NADPH and ribose-5-phosphate B. it uses glucose-6-P as a substrate when producing NADPH and CO2 C. glucose-6-phosphate dehydrogenase is the control enzyme and it is regulated by the NADPH concentration of the cell D. if it is producing more than twice as much NADPH as ribose-5-P, it can produce glyceraldehyde-3-P and fructose-6-P E. it is found in the mitochondria of liver, muscle, and brain but is absent from most other tissues of the body
E
the key glutamate or aspartate residue on the c-ring of ATP synthase works most directly with what other key feature of the complex to transport protons across the inner mitochondrial membrane? A. the catalytic site in the alpha-beta subunits B. the gamma subunit C. oligomycin D. the F0 knob E. the two half-channels in the a subunit
E
the regulated steps in the Calvin cycle are catalyzed by which types of enzymes? A. aldolases and transketolases B. aldolases and kinases C. aldolases and isomerases D. RuBisCO and transketolases E. RuBisCO, a kinase, and bisphosphatases
E
which fo the following is NOT a mechanism by which the activity of the pyruvate dehydrogenase complex is regulated? if all of the following are used to regulate the pyruvate dehydrogenase activity, choose (e). A. feedback inhibition B. covalent modification (reversible phosphorylation) C. hormonal regulation D. transcriptional regulation E. all of the above are used to regulate pyruvate dehydrogenase activity
E
which molecule accepts the CO2 in the carbon-fixing reaction of the Calvin cycle? A. dihydroxyacetone phosphate (DHAP) B. glyceraldehyde-3-phosphate (GAP) C. xylulose-5-P (Xu5P) D. ribose-5-P (R5P) E. ribulose-1,5-bisphosphate (RuBP)
E
which of the following statements about glycogen and its catabolism is NOT true? A. the function of glycogen in liver is to supply glucose to the blood when needed B. the function of glycogen in muscle is to supply energy for muscle contraction C. when glycogenolysis is active in the liver, glycolysis is usually inactive D. there is more glycogen stored in all skeletal muscle cells combined than in the liver E. muscle, but not liver, has the enzyme glucose-6-phosphatase
E liver is an exportable rather than usable glucose reservoir therefore, it would contain the enzyme glucose-6-phosphatase that converts glucose-6-phosphate to glucose in order to be exported.
Liver cells use several specialized proteins to (directly or indirectly) aid in exporting the product of glycogenolysis and gluconeogenesis. Which ONE of the following correctly lists those proteins? A. Glucose-6-phosphatase, hexokinase I, GLUT4 B. Phosphoglucomutase, hexokinase IV, GLUT4 C. Phosphoglucomutase, hexokinase I, GLUT2 D. Glucose-6-phosphatase, hexokinase IV, GLUT4 E. Phosphoglucomutase, hexokinase I, GLUT4 F. Phosphoglucomutase, hexokinase I, GLUT4 G. Glucose-6-phosphatase, hexokinase I, GLUT2 H. Glucose-6-phosphatase, hexokinase IV, GLUT2 I. Phosphoglucomutase, hexokinase IV, GLUT2
H
Transketolase is an enzyme involved with the Calvin cycle and pentose phosphate pathway, both of which we'll learn later in the quarter. A sample reaction for a transketolase in below. (see post lecture question 20). what cofactor in the pyruvate dehydrogenase complex do you predict will also be in transketolase enzyme?
TPP transketolase reaction involves transfer of 2 carbons at a carbonyl. this is similar to the first reaction of PDH where TPP is used to take 2 carbons, so TPP is used as a cofactor.
why doesn't complex II simply use NADH as a reduced electron carrier so it can pump electrons too?
a stronger oxidant is required to extract the e- because succinate has a high affinity for e- also, if NAD+ accepted e- when succinate is oxidized to fumarate, then the reduction potential would be -0.351 V. This would cause the standard free energy change to be very positive and this reaction would be unfavorable
pyruvate dehydrogenase complex deficiency (PDCD) is a rare disorder or carbohydrate metabolism caused by abnormalities in the genes that encode the components of the pyruvate dehydrogenase complex. the most common presenting features of PDCD include poor feeding, lethargy, and rapid breathing due to increased blood levels of lactic acid. why would PDH deficiency lead to a buildup of lactic acid? How would this affect brain activity?
abnormalities in pathway would lead to a buildup of pyruvate and NADH from glycolysis. This would therefore shunt pyruvate through lactate dehydrogenase, leading to an overproduction of lactic acid. however, conversion of pyruvate to lactate does not yield enough ATP. The citric acid cycle cannot take place as there is little acetyl coA. therefore, there are no reduced coenzymes (NADH, FADH2) to enter oxidative phosphorylation stage and not enough ATP is made. without ATP, cells (neurons) can't cary out work and the brain and body can't function properly.
after fat stores are depleted during prolonged faster, muscle will be broken down so amino acids can be used for gluconeogenesis. of the amino acids below, which ones do you expect to enter gluconeogenesis in a single step? what metabolite do they enter as? K, D, A, F
alanine (A) and aspartate (D) can enter gluconeogenesis as pyruvate and oxaloactate, respectively
as discussed in lecture, certain molecules inhibit complexes in electron transport. rotenone is a toxin made from plants that is extremely toxic to insects and fish by inhibiting complex I. Antimycin A is a bacterial toxin that is also harmful to fish by inhibiting complex III. if an invasive species of fish is in a recreational pond, which molecule would be more potent poison to eliminate the fish?
antimycin A would be more potent. if complex III is inhibited, then e- can't flow through complex III or IV and 6 fewer protons will be pumped, leading to less energy to make ATP. If complex I is inhibited, e= can still enter ETC in complex II and only 4 fewer protons are pumped
which carbon on isocitrate comes from the methyl carbon of acetyl-CoA during the first pass through the citric acid cycle picture on pollEv 20
carboxyl group and a CH2 group no way methyl group will be converted to carrboxyl COO-
which complexes of the electron transport system carry Fe-S clusters?
complex I, II, III as you go down the ETC, the standard reduction potential of the redox elements increases (becomes more positive). therefore, it makes sense that only the first 3 complexes would transfer e- through Fe-S clusters which have a more negative standard reduction potential compared to cytochromes
what is the order of electron carriers and protein complexes in the light reactions?
e- carriers: H2O --> P680 --> plastoquinone --> plastocyanin --> P700 --> ferrredoxin --> NADPH prrotein complexes: light harvesting complex --> PSII --> cytochrome b6f --> plastocyanin --> PSI --> ferredoxin --> FNR
in plant nutrition, nutrients are divided into macronutrients or micronutrients depending on the amount needed by the plant. magnesium is a macronutrient and manganese is a micronutrient. given their roles in photosynthesis, why would a plant need more magnesium than manganese?
each chlorophyll molecule contains a magnesium ion and 4 manganese ions are used in the oxygen evolving complex in PSII. each PSII has a single oxygen evolving complex, while each photosystem has hundreds of chlorophyll molecules in their light harvesting complexes. the large amount of chlorophyll molecules means a plant needs a large amount of magnesium to remain healthy
for each of the amino acids you selected, how many NTPs and reducing equivalents are used to make 1 molecule of glucose if only that amino acid is used for input?
for alanine, it enters as pyruvate and will go through the entire path of gluconeogenesis, so it will require 6 NTPs andd 2 NADHs to make 1 glucose. for aspartate, it will enter as oxaloacetate which bypasses the pyruvate carbroxylase reaction. therefore, it will only use 4 NTPs and 2 NADHs
how would efficiency be affected if the glycerophosphate shuttle is used to shuttle electrons into the mitochondria vs. the malate shuttle? Why would the cell need the glycerophosphate shuttle?
if glycerorphosphate shuttle is used, the e- in cystolic NADH are passed to FAD in the mitochondria, as opposed to the malate shuttle where cystolic NADH is transferred to mitochondrial NAD+ through malate. Since e- in FADH2 produce 1 fewer ATP molecule than NADH, this would lead to 31 ATP molecules being synthesized instead of 32 ATPs. although it is less efficient, the cell may want to convert cystolic NADH to NAD+ if it is doing lots of glycolysis
where in the pyruvate dehydrogenase complex is acetyl-CoA being made? picture in lecture 19 pollEv
in the purple center in E2
atrazine is an herbicide commonly used to control weeds in corn fields. when atrazine is applied to chloroplasts, oxygen evolution and ATP production ceases. If an uncoupler is added, there is no change, and if an external electron acceptor is added, only oxygen evolution begins again. what process of photosynthesis must atrazine affect?
it must affect PSII and cytochrome b6f
the substance dichlorophenyldimethylurea (DCMU) is an herbicide that inhibits photosynthesis by blocking electron transfer between plastoquinones in the photosystem II would you expect DCMU to interfere with cyclic phosphorylation?
no, because plastoquinones are not involved in this process
Which TWO of the following statements about glucose-1-phosphate are CORRECT? (Pick TWO.) A. It can enter glycolysis at the step catalyzed by phosphoglucose isomerase. B. It can be isomerized to form glucose-6-phosphate. C. Its production is elevated when [glucose-6-phosphate] is low. D. It can exit liver cells via bidirectional GLUT transporters. E. It can directly enter the oxidative phase of the pentose phosphate pathway. F. It can become activated using UTP for glycogenesis.
not sure
suppose a researcher is carrying out studies in which she adds a nonphysiological electron donor to a suspension of chloroplasts. illumination of chloroplasts yields oxidation of the donor
observe oxidation state of plastoquinones and plastocyanin using illumination at both 700 and 680 nm. if only P700 is involved, these will be oxidized. if only P680 they will be reduced. if both, simultaneous illumination at the 2 wavelengths will give enhanced oxidation of the donor
the NADH and FADH2 molecules produced by glycolysis and the citric acid cycle are used to create 2.5 and 1.5 ATP per electron carrier respectively. with this info: how efficient is the oxidation of one mole of glucose in standard conditions if combustion of glucose is -2480 kJ/mol and ATP hydrolysis is -30.5 kJ/mol?
per 1 mole of glucose, 4 mol of ATP, 10 mol NADH, and 2 mol FADH2 arer produced in glycolysis and the citric acid cycle. using the ETC, there will be 4 + 10(2.5) + 2(1.5) = 32 ATP if all the ATP was hydrolyzed under standard conditions, it would produce -976 kJ/mol. so it would be -976/-2840 = 34% efficient under standard conditions
much of the work to determine the structure of the pyruvate dehydrogenase complex was done here at UW in Wim Hol's lab. when studying the interactions between the E2 peripheral binding domain and E3 , the group found that an "electrostatic zipper" created the interactions between the two subunits. If AspB34 in the figure was mutated to a His residue, what effect would you expect on pyruvate dehydrogenase complex activity?
replacing a negatively charged aspartate residue with a basic histidine residue would weaken the strong electrostatic interactions between 2 domains. Since E2 and E3 would bind more weakly, they ay dissociate more. This would decrease substrate channeling used by PDH, and thus lower the rate fo the enzyme complex
a patient develops painful muscle cramps and tires easily when exercising. their liver and other muscles are normal in size. what enzyme in glycogen metabolism do you expect to be dysfunctional? what dietary changes would you suggest to alleviate the symptoms?
symptoms seem to only arise when exercising, suggesting that muscles are not getting glucose needed to make ATP while exercising. an enzyme that would affect the rate of glycogen breakdown in exercise is muscle glycogen phosphorylase. alternatively, the branching enyzme could be dysfunctional, leading to slowing breakdown fo glycogen, but usually branching disorders are associated with larger muscle and liver sizes because glycogen molecules are less compact. to help with the exercise fatigue, the patient could change their diet so they have more creatine available to resupply ATP in exercise or they could eat sugar before exercising to ensurer that their blood glucose levels are high and can rely less on glycogen.
which would be the last glycosidic bond broken before glycogen phosphorylase stalls? see image in poll ev. 25
the bond between the 4th and 5th molecule before the branch
which glycosidic bond would the branching enzyme break to make a new branch? see image in poll ev. 26
the bond between the 5th and 6th molecule before the branch
cancer cells rely heavily on the pentose phosphate pathway to proliferate. their proliferation requires nucleotides and fatty acids for membranes (which requires NADPH), creates reactive oxygen species, and uses the glycolytic pathway. why is the pentose phosphate pathway such an important pathway for cancer cells?
the pentose phosphate pathway provides a way for cancer cells to generate intermediates needed for grrowth while continuing to use glycolysis for ATP production. both NADPH and ribose-5-phosphate are made during the oxidative phase. NADPH can be used directly for fatty acid synthesis, or it can reduce glutathione and is protecting the cell from reactive oxygen species. ribose-5-phosphate is used in nucleotide synthesis for the replicated DNA. some of the ribose-5-phosphate can go through the non-oxidative pathway to generate intermediates in glycolysis to produce ATP for the cells.
the number of c subunits in ATP synthase varies by organism. if bovine ATP synthase has 8 c subunits and yeast has 10 c subunits, which organism produces more ATP per NADH molecule?
while the number of c subunits varies, the number of alpha and beta subunits remain the same at 3, so for one full tun of the c ring, 3 ATPs are created for both organisms. since bovine ATP synthase requires fewer protons to complete one full turn, it will produce more ATP.
