Presentation on theme: "Cellular Respiration: Harvesting Chemical Energy"— Presentation transcript:
1 Cellular Respiration: Harvesting Chemical Energy Chapter 9Cellular Respiration: Harvesting Chemical Energy
2 QuizDefine oxidation.Define reduction.List the four ways an enzyme reduces EA.
3 Quiz Define oxidation. Define reduction. The gain of an electron resulting in a reduced charge.Define reduction.The loss of an electron resulting in an increased charge.List the four ways an enzyme reduces EA.Orientating the substrate correctly.Stressing the bonds of the substrateProviding the correct chemical environmentCovalently bonding to the substrate
5 Review of nrg Cycle Energy Flows into an ecosystem as sunlight and leaves as heat.Our cells get nrg from the food we eat.Turn chemical nrg in food to ATP, CO2, and H2O
6 Overview of Cellular Respiration An overview of cellular respiration3 Phases:Glycolysis*Citric Acid Cycle (AKA Krebs Cycle)Oxidative phosphorylationEach phase yields some ATP
7 Both glycolysis and the citric acid cycle Key ConceptsBoth glycolysis and the citric acid cycleCan generate ATP by substrate-level phosphorylationFigure 9.7EnzymeATPADPProductSubstrateP+
8 Substrate level phosphorylation Enzyme transfers a phosphate group from a substrate to an ADP.Substrate is an intermediary molecule in Glycolysis or the CAC.Makes only one ATP at a time.
9 The Breakers: A posse of enzymes and coenzymes The Players:The Victim: GlucoseGets broken down and has its e-’s stolenThe Breakers: A posse of enzymes and coenzymesWill be introduced in each sceneThe Thieves: Electron CarriersNAD+, FADCarry off electrons to the site of Oxidative PhosphorylationThe motive: Make ATP
10 Inner Mitochondrial Membrane (Cristae) The scene:A dark stormy night, inside the cell. The action takes place in three areas:CytosolSite of Glycolysis.Mitochondrial MatrixSite of the Citric Acid Cycle.Inner Mitochondrial Membrane (Cristae)Site of Oxidative phosphorylation.
12 9.2 Scene 1: The cytoplasm Glycolysis Means “splitting of sugar” Breaks down (oxidizes) glucose into pyruvate.2 ATP2 NAD+4 ADP
13 Glycolysis consists of two major phases Energy investment phase5 stepsEnergy payoff phase
14 Special NoteIt is more important that you understand the overall processYou will not be examined on the enzymes catalyzing each step of this or the intermediate conformations.However, it is advisable that you know them and are familiar with how the process occurs.
15 A closer look at the nrg investment phase 1 Glucose + 2 ATP=2 Glyceraldehyde 3-Phosphate + 2 ADPGlucose gets phosphorylated 2 times.After 2nd phosphorylaton, Molecule gets split into 2 3-carbon molecules
16 A closer look at the nrg payoff phase 2 3-Carbon sugar + 2 NAD+ +2Pi=2 Pyruvates + 2H2O +4 ATP +2NADH + 2 H+Pyruvates continue into CACNADH+H+ goes to Oxidative phosphorylation.4 ATP’s are generated2 waters are generated
17 9.3- Scene 2: The mitochondrial Matrix Site of the Citric Acid CycleCompletes the energy-yielding oxidation (breakdown) of organic moleculesKey Characters (names you should know):CoEnzyme AAcetyl CoAOxaloacetate
18 Pyruvate must first be converted to acetyl CoA using Coenzyme A CYTOSOLMITOCHONDRIONNADH+ H+NAD+231CO2Coenzyme APyruvateAcetyle CoASCoACCH3OTransport proteinO–Figure 9.10
28 QuizIn CAC, what is the net yield, in terms of ATP and NADH, of one molecule of glucose?What is the molecule to which pyruvate is combined in the fist step of the Citric Acid Cycle?What are the two types of fermentation.Fermentation occurs under _____ conditions.
29 List the two types of fermentation. (2 pts) QuizIn CAC, what is the net yield, in terms of ATP and NADH, of one molecule of glucose? (2 points) 2 ATP and 6 NADHWhat is the molecule to which pyruvate is combined in the fist step of the Citric Acid Cycle? (2 points) OxaloacetateList the two types of fermentation. (2 pts)Alcohol and lactic AcidFermentation occurs under anaerobic conditions. (1 Point)
30 Chemiosmosis couples electron transport to ATP synthesis 9.4 Act 3 Inner mt MembraneChemiosmosis couples electron transport to ATP synthesisNADH and FADH2 from glycolysis and CACDonate electrons to the electron transport chain, which powers ATP synthesis via oxidative phosphorylation
31 The Pathway of Electron Transport E- gradually lose energy.(where does it go?)At the end of the chainElectrons are passed to oxygen, forming water
32 At certain steps along the electron transport chain Pumps H+ to the OUTSIDE of the inner membrane.Where actually is this, then, in the mt?What type of transport is this?
33 The resulting H+ gradient Stores energyDrives chemiosmosis in ATP synthaseIs referred to as a proton-motive force
34 ChemiosmosisIs an energy-coupling mechanism that uses energy (H+ gradient) to drive cellular work.In this case, the H+ gradient is across the inner mt membrane,Work is making ATP
37 Chemiosmosis: The Energy-Coupling Mechanism ATP synthaseIs the enzyme that actually makes ATP
38 An Accounting of ATP Production by Cellular Respiration During respiration, most energy flows in this sequenceGlucose to NADH to electron transport chain to proton-motive force to ATP
39 About 40% of the energy in a glucose molecule Is transferred to ATP during cellular respiration, making approximately 38 ATP
40 When electrons flow along the electron transport chains of mitochondria, which of the following changes occur?The pH of the matrix increases.ATP synthase pumps protons by active transport.The electrons gain free energy.The cytochromes of the chain phosphorylate ADP to form ATP.NAD+ is oxidized.Answer: aSource: Campbell/Reece - Biology, Sixth Edition, EOC Self-Quiz Question #6
41 In the 1940s, some physicians prescribed low doses of a drug called dinitrophenol (DNP) to help patients lose weight. This unsafe method was abandoned after a few patients died. DNP uncouples the chemiosmotic machinery by making the lipid bilayer of the inner mitochondrial membrane leaky to H+. What impact does this have on ATP production? *reduces substrate level phosphorylationsincreases substrate level phosphorylationsreduces oxidative level phosphorylationsincrease oxidative level phosphorylationsThis would have no impact on ATP production.Answer: cSource: Campbell/Reece - Biology, Sixth Edition, EOC Process of Science QuestionDiscussion Notes for the InstructorThere are several questions which can be asked to guide the discussion of this question including:Which portion of the cellular respiration pathway involves hydrogen ions and the mitochondrial membrane?How do hydrogen ions cause ATP production?If the hydrogen ion concentration changes how does this impact ATP?Using these questions as an outline, discussion of the choices might look like this:Choice A, substrate level phosphorylations do not involve hydrogen ions.Choice B, substrate level phosphorylations do not involve hydrogen ions.Choice C, correct.Choice D, if there are fewer hydrogen ions to move through the ATP synthetase complexes less ATP will be produced.Choice E, hydrogen ion movement has a direct impact on ATP production.
42 Glucose, made from six radioactively labeled carbon atoms, is fed to yeast cells in the absence of oxygen. How many molecules of radioactive alcohol (C2H5OH) are formed from each molecule of glucose?1236Answer: cSource: Taylor - Student Study Guide for Biology, Sixth Edition, Test Your Knowledge Question #15
43 Cyanide is a poison that blocks the passage of electrons along the electron transport chain. Which of the following is a metabolic effect of this poison?The lower pH of the intermembrane space is much lower than normal.Electrons are passed directly to oxygen, causing cells to explode.Alcohol would build up in the cells.NADH supplies would be exhausted, and ATP synthesis would cease.No proton gradient would be produced, and ATP synthesis would cease.Answer: eSource: Taylor - Student Study Guide for Biology, Sixth Edition, Test Your Knowledge Question #20
44 Which kind of metabolic poison would most directly interfere with glycolysis? an agent that reacts with oxygen and depletes its concentration in the cellan agent that binds to pyruvate and inactivates itan agent that closely mimics the structure of glucose but is not metabolizedan agent that reacts with NADH and oxidizes it to NAD+an agent that inhibits the formation of acetyl coenzyme AAnswer: cSource: Barstow - Test Bank for Biology, Sixth Edition, Question #5
45 You have a friend who lost 15 pounds of fat on a diet. Where did the fat go (how was it lost)? *It was released as CO2 and H2O.Chemical energy was converted to heat and then released.It was converted to ATP, which weighs much less than fat.It was broken down to amino acids and eliminated from the body.It was converted to urine and eliminated from the body.Answer: aSource: Barstow - Test Bank for Biology, Sixth Edition, Question #63Discussion Notes for the InstructorThere are several questions which can be asked to guide the discussion of this question including:What are fats composed of and how does that relate to the answer choices?How are fats metabolized and what are the end products of this?Using these questions as an outline, discussion of the choices might look like this:Choice A, correct. The mass of a fat is in the atoms of the molecule. When fats are metabolized these atoms end up in CO2 and H20Choice B, while this is somewhat true, energy has no mass and therefore cannot be the source of the weight loss.Choice C, When fats are metabolized the energy in them is used to make ATP, but the fats are not converted into ATP (a common misconception)Choice D, Fats are not composed of amino acidsChoice E, Urine is generally the result of nitrogenous waste product, fats (i.e. Triglycerides contain little nitrogen if any and therefore do not result in urine production)