Bio 330 Final Exam Questions With 100% Correct Answers

Name the three stages of respiration. Which of these stages does not require oxygen? - correct answers 1. Glycolysis 2. Citric Acid Cycle/Tricarboxylic Acid cycle/Krebs Cycle 3.Electron Transport/Oxidative phosphorylation Glycolysis does not require oxygen Where in the cell does glycolysis occur, and what are the products of this process? - correct answers It occurs in the cytosol. Glucose is metabolized into two molecules of pyruvic acid or pyruvate. And there is a net gain of 2 ATP and 2NADH What are the two energetic stages of glycolysis? - correct answers Energy-requiring steps: 2 ATP used to prime initial reactions Energy-releasing steps: 4 ATP made and 2 NADH. How many ATP, FADH2, and NADH are used to prime glycolysis? - correct answers 2 molecules of ATP are used to prime for glycolysis How many ATP, FADH2, and NADH are produced by the energy-yielding steps in glycolysis? - correct answers 4 ATP 2 NADH In glycolysis, why is ATP and not just a Pi from the cell used to phosphorylate glucose or fructose-6-phosphate? - correct answers Since the reactions are energetically unfavorable, they must be coupled to ATP hydrolysis in order to proceed forward and favor the production of glucose-6-phosphate and fructose-1,6 biphosphate Name an enzyme that catalyzes the first step in glycolysis - correct answers Hexokinase uses the first ATP to phosphorylate glucose to glucose-6-phosphate Name an enzyme that catalyzes the conversion of fructose-6-P into fructose-1, 6-biphosphate in glycolysis - correct answers Phosphofructokinase In glycolysis, which enzyme catalyzes the key rate limiting step? - correct answers Phosphofructokinase is inhibited by ATP binding to its allosteric site How does excess supply of ATP in the cell shut down glycolysis? - correct answers The excess ATP binds to the allosteric site of Phosphofructokinase, rendering it inactive. This results in the build up of glucose-6-phosphate, which inhibits the hexokinase by allosteric regulation. Shutting down the glycolytic pathway Name two 3-carbon compounds that are formed by splitting of fructose-1,6-biphosphate. Which of these two will be further metabolized in the cell? - correct answers Glyceraldehyde-3-phosphate(GAP) and its isomer dihydroxylacetone phosphate(DHAP). Only GAP can be further metabolized In glycolysis, at which level is NADH produced? - correct answers Energy releasing steps. GAP converted to 1,3 bis-PGA Name two high energy intermediates in the glycolytic pathway - correct answers 1. 1,3 biphosphoglycerate 2. phosphoenolpyruvate (PEP) At which two steps in the glycolytic pathway will ∆G be highly negative? Explain your answer - correct answers 1. When GAP is phosphorylated by Pi to yield 1-3,BIS PGA 2. When 3-PGA is converted to PEP Hydrolysis of high energy phosphates of PEP and 1-3, BIS PGA drives ATP synthesis What is substrate level phosphorylation, and where in glycolysis does it occur? - correct answers It is the direct transfer of a high energy phosphate group from the substrate to another molecule, resulting in the formation of ATP. This occurs when high energy phosphate from 1,3-bisPGA drives ATP synthesis from ADP. It also occurs during the conversion of PEP to pyruvate when its coupled to ATP synthesis What are two possible fates of NADH produced in glycolysis? - correct answers 1. Anaerobic pathways use it for fermentation 2.It donates it's electrons to the ETC In alcoholic fermentation, which enzyme removes CO2 from pyruvate? - correct answers pyruvate decarboxylase Use a flow chart to show the conversion of pyruvate to ethanol during alcoholic fermentation - correct answers Releases CO2, acetaldehyde, and ethanol Show in details the conversion of pyruvate to lactate during lactate fermentation - correct answers Directly reduced by NADH to form lactate and releases NAD+ Does the mitochondrion have the pyruvate transporter? Justify your answer - correct answers Yes, in the presence of oxygen pyruvate is able to enter the mitochondria using transporters. Without oxygen the channels are closed Where does TCA cycle take place, and does it require oxygen? - correct answers Takes place in the fluid matrix of the mitochondrion, and it does require oxygen What is the name of the enzyme complex that converts pyruvate into acetyl-CoA? - correct answers Pyruvate dehydrogenase enzyme complex (PDH) How many enzymes make up the PDH complex and which are the 3 required bound factors, and 2 required unbound factors? - correct answers Consists of three different enzymes, E1 E2 and E3 which form a quarternary structure. The 3 bound factors: Thiamine pyrophosphate(TPP), Lipoic Acid, Flavin adenine dinucleotide(FAD). The 2 unbound factors: Free coenzyme A(CoASH) and NAD+ Use a simple reaction to show the substrates and products of oxidative decarboxylation of pyruvate by the pyruvate dehydrogenase complex - correct answers SUBSTRATES: pyruvate, CoASH, and NAD+. PRODUCTS : acetylCoA, NADH, and CO2 How is the activity of pyruvate dehydrogenase regulated by covalent modification? - correct answers Covalent modification is the ATP-dependent phosphorylation of PDH by a kinase. Ammonia stimulates kinase and promotes phosphorylation of PDH. Pyruvate inhibits kinase, preventing phosphorylation of PDH. Which two products of the pyruvate dehydrogenase could inhibit the activity of this enzyme complex? Explain how this inhibition might happen - correct answers Acetyl-CoA and NADH. They inhibit the enzyme complex by utilizing feedback inhibition, binding to the allosteric site in order to prevent the activity of the enzyme complex. In the oxidative metabolism of one molecule of glucose, how many times does the TCA cycle run? explain. - correct answers Twice because one molecule of glucose produces two molecules of pyruvate. Name the 4-carbon compound, which is an acceptor of acetly-CoA in the TCA cycle - correct answers Oxaloacetate Which 6-carbon compound is the first product of the TCA cycle? - correct answers Citrate In the TCA cycle, which compound is regenerated? - correct answers Oxaloacetate In the TCA cycle, which compound is the first to be oxidized and decarboxylated. Name the 3 products of this reaction - correct answers Isocitrate. It produces NADH, CO2, and a-ketoglutarate In the TCA cycle, which 5-carbon compound is oxidized and decarboxylated. Name the 3 products of this reaction - correct answers A-ketoglutarate. It produces NADH, CO2, succinyl-coA In the TCA cycle, at which level are GTP(ATP) and FADH2 formed? - correct answers Succinyl-coA Level In the TCA cycle, which intermediate is oxidized to form NADH and oxaloacetate? - correct answers Succinate is converted to malate In a single cycle of citrate to oxaloacetate (OAA), how many CO2, ATP, NADH, and FADH2 are formed? - correct answers 2 CO2, 1 ATP, 3 NADH, 1 FADH2 In the conversion of 2 pyruvates to 2 oxaloacetates, how many molecules of CO2, ATP, NADH, and FADH2 are formed? - correct answers 6 CO2, 2 ATP, 6 NADH, 2 FADH2 What does it mean to say glucose is completely metabolized or oxidized? - correct answers Glucose loses all of its carbons in the form of CO2 If carbons in glucose were tagged [14 C-glucose], which products or intermediates of respiration would be radioactive, i.e. contain [14C]? Would [14C] appear in pyruvate, acetyl-CoA, citrate, isocitrate, a-ketoglutarate, succinyl-CoA, ATP, NADH, FADH2, CO2, and H2O? Justify your answer for each molecule. - correct answers Pyruvate-yes. Acetyl-CoA: yes. Citrate yes. Isocitrate yes. A-ketoglutarate: yes. Succinyl-CoA no. ATP, NADH, FADH2 are all no. CO2 yes. H2O no. What happens to the high energy electrons from NADH and FADH2 which are produced in the TCA cycle? - correct answers They get sent to the electron transport chain Where in the mitochondria does oxidative phosphorylation or electron transport occur? Justify your answer in terms of the localization of the protein carriers. - correct answers Inner membrane of the mitochondria What are the precise names of complexes I, II, III, IV, and V in the ETC? - correct answers 1. NADH dehydrogenase 2. succinate dehydrogenase 3. Cytochrome bc 4. Cytochrome C Oxidase 5. ATP synthase What causes protons to be pumped from the mitochondrial matrix into the intermembrane space, and what kind of energy is stored in these protons? - correct answers Potential energy is stored in these. As a result of the energy transfer from complex to complex. Describe the role of protein complex V in electron transport - correct answers ATP synthase. Harvests the stored energy from the proton gradient. This energy couples to ATP synthesis. ADP +Pi =ATP Explain the chemiosmotic theory. Who proposed the initial hypothesis? - correct answers Coupling electron transport to ATP synthesis. Proposed by Peter Mitchell Where does electrons from NADH enter the ETC, and how many protons are pumped across the inner membrane per pair of electrons transferred at this complex? - correct answers Enter at complex one. 4 protons are pumped out for every 2 electrons that are transferred. What is ubiquinone? Give the function of this molecule in electron transport. - correct answers Ubiquinone is a small hydrophobic molecule that carries e- from 1 to 3 or 2 to 3. Where does electrons from FADH2 enter the electron transport chain, and how many protons are pumped across the inner membrane per pair of electrons transferred at this complex. - correct answers Complex 2. No protons are pumped out at complex two. Which TCA intermediate can enter the ETC at complex II, and how many ATPs are produced when this compound is oxidized? - correct answers Succinate. 2 ATPs are produced when this compound is oxidized at either complex 3 or 4 only. Where in the mitochondria is cytochrome c located and what is the function of this molecule? - correct answers Its in the intermembrane space, but it is bound to the outer face of the inner membrane. This makes it hydrophillic At complex III, to which carrier are the electrons from ubiquinone transferred to and how many protons are pumped across the inner membrane per pair of electrons transferred at this complex. - correct answers Ubiquinone transfers its electrons to cytochrome b. Four protons pumped out for every 2 e- transferred. At complex IV, which molecule is the final acceptor of electrons and what is the product? - correct answers O2. It forms H2O At complex IV, how many protons are pumped across the inner membrane per pair of electrons recieved, and what is the fate of the other two protons? - correct answers 2 protons are pumped out for every 2 e-. The other 2 protons are used to form H2O How many ATPs are produced by one NADH and one FADH2 that is oxidized via the ETC? - correct answers NADH =3 FADH2=2 Summarize the energy yield(ATP produced) from the complete oxidation of one molecule of glucose via Glycolysis, TCA cycle and Electron transport. - correct answers 36-38 ATP total If an organ has mitochondria with NADH transporters, what would be the total yield of ATP from the complete oxidization of one molecule of glucose? - correct answers With transporter: 38 ATP If cells have mitochondria with no NADH transporters, what is the possible total yield of ATP from the complete oxidization of one molecule of glucose? explain. - correct answers Without transporter: 36-38 ATP Name a compound, which could inhibit complex I and its mode of action - correct answers Rat poison, Rotenone. Blocks the reduction of oxidized ubiquinone Which compound could inhibit complex II and what is its structural analog? - correct answers Malonate. Its analog is succinate. Name two compounds which could inhibit complex III and their mode of action - correct answers Myxothiazol: blocks oxidation of reduced ubiquinone Antimycin A: blocks reduction of oxidized ubiquinone Name two compounds which could inhibit complex IV and their mode of action - correct answers Cyanide and carbon monoxide. They compete for electrons with O2. Name an antibiotic, which could inhibit complex V and its mode of action - correct answers Oligomycin. Prevents the H+ translocation through the complex, which inhibits ATP synthesis and limits O2 uptake by the mitochondria. What is the process called by which fatty acids are degraded by removal of 2 carbons at a time? - correct answers Beta oxidation After each round of fatty acid B-oxidation, what would be the 4 main products? - correct answers NADH, FADH2, Acetyl-CoA, fatty acyl CoA