* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Download Chapter 9 Cell Respiration
Biosynthesis wikipedia , lookup
Amino acid synthesis wikipedia , lookup
Lactate dehydrogenase wikipedia , lookup
Basal metabolic rate wikipedia , lookup
Fatty acid synthesis wikipedia , lookup
Butyric acid wikipedia , lookup
Mitochondrion wikipedia , lookup
Glyceroneogenesis wikipedia , lookup
Photosynthesis wikipedia , lookup
Fatty acid metabolism wikipedia , lookup
Evolution of metal ions in biological systems wikipedia , lookup
NADH:ubiquinone oxidoreductase (H+-translocating) wikipedia , lookup
Photosynthetic reaction centre wikipedia , lookup
Nicotinamide adenine dinucleotide wikipedia , lookup
Phosphorylation wikipedia , lookup
Light-dependent reactions wikipedia , lookup
Electron transport chain wikipedia , lookup
Microbial metabolism wikipedia , lookup
Biochemistry wikipedia , lookup
Adenosine triphosphate wikipedia , lookup
Oxidative phosphorylation wikipedia , lookup
Cellular Respiration: Harvesting Chemical Energy Chapter 9 Life Is Work • Living cells require energy from outside sources • Plants E from ? • Animals E from ? Energy flows into ecosystem as light Light energy ECOSYSTEM CO2 + H2O Photosynthesis in chloroplasts Cellular respiration in mitochondria Organic + molecules O2 ATP ATP powers work ATP powers most cellular work Heat energy Energy leaves as heat • Photosynthesis – Organelle = ? – Generates O2 and organic molecules • Cellular respiration – Organelle = ? – Uses organic molecules to generate ATP Catabolic Pathway review • Organic molecules have potential (chemical) energy • Exergonic rxns break down organic molecules energy (and heat) Cellular Respiration • Aerobic respiration – Uses O2 – ATP produced Anaerobic respiration Does not use O2 ATP produced Cellular respiration 1. Glycolysis Occurs in cytoplasm Anaerobic Glucose + 2NAD+ + 2ATP 2 pyruvate+ 2NADH + 4ATP • 1 glucose 2 ATP and 2 pyruvate • Glucose oxidized to pyruvate (loses electron) • NAD+ reduced to NADH (gains electron) Glycolysis Electron donor Electrons carried via NADH mitochondrion Glycolysis Pyruvate Glucose Cytosol ATP Substrate-level phosphorylation CYTOSOL Glycolysis 1. Energy investment phase uses 2 ATP 2. Energy payoff phase – 4 ATP produced – 2NAD+ reduced to 2NADH – 1 glucose split to 2 pyruvate Glucose + 2NAD+ + 2ATP 2 pyruvate+ 2NADH + 4ATP Energy investment phase Glucose 2 ADP + 2 P 2 ATP used 4 ATP formed Energy payoff phase 4 ADP + 4 P 2 NAD+ + 4 e – + 4 H+ 2 NADH + 2 H+ 2 Pyruvate + 2 H2O Net Glucose 4 ATP formed – 2 ATP used 2 NAD+ + 4 e – + 4 H+ 2 Pyruvate + 2 H2O 2 ATP 2 NADH + 2 H+ 10 enzymatic steps in glycolysis 2. Citric acid cycle (Krebs cycle) • mt matrix – Matrix is enclosed by the inner membrane Citric acid cycle 2Pyruvate + NAD+ + FADH 2ATP + NADH + FADH2 + CO2 + H2O Where did the pyruvate come from? How did it get into the mt matrix? # ATP generated? Waste product? Where does it go? NADH and FADH2 can donate electrons later What happened to the sugar? O2? Electrons carried via NADH and FADH2 Electrons carried via NADH Citric acid cycle Glycolysis Pyruvate Glucose Mitochondrion Cytosol ATP ATP Substrate-level phosphorylation Substrate-level phosphorylation MITCHONDRION citric acid cycle 1. Convert 2pyruvate to 2acetyl A (before cycle) Acetyl CoA links glycolysis to cycle Pyruvate diffuses into mt matrix and is converted to acetyl CoA CYTOSOL MITOCHONDRION NAD+ NADH + H+ 2 1 Pyruvate 3 CO2 Coenzyme A Acetyl CoA Transport protein Cellular Respiration: Bioflix animation • 2. The citric acid cycle Pyruvate CO2 NAD+ 8 enzymatic steps CoA NADH + H+ Acetyl CoA CoA ATP: For each pyruvate? CoA Citric acid cycle FADH2 2 CO2 For each glucose? 3 NAD+ 3 NADH FAD + 3 H+ ADP + P i ATP For each turn of cycle? Summary of citric acid cycle • Per molecule glucose =2 pyruvate – NADH and FADH 2 electron donors – 2 ATP (1 per turn) per glucose • CO 2 produced (2 per turn) out • mt matrix BIO 231 TCA cycle animation: Acetyl CoA formation Text Activity: The Citric Acid Cycle 3. oxidative phosphorylation in mt cristae Cristae compartmentalize mt inner membrane = more surface area What happens? NADH and FADH 2 donate electrons in the series of steps Oxygen accepts electrons water H+ proton gradient ADP + P ATP 34 ATP produced Add up the ATP yield per glucose: Glycolysis + Citric acid cycle + Ox Phos = Oxidative phosphorylation: 34 ATP Electrons carried via NADH and FADH2 Electrons carried via NADH Citric acid cycle Glycolysis Pyruvate Glucose Oxidative phosphorylation: electron transport and chemiosmosis Mitochondrion Cytosol ATP ATP ATP Substrate-level phosphorylation Substrate-level phosphorylation Oxidative phosphorylation Stepwise Energy Harvest via Electron Transport Chain 1. Controlled rxns H2 + 1/2 O2 2H (from food via NADH) 2 H+ + 2 e– Explosive release of heat and light energy 1/ 2 Controlled release of energy for synthesis of ATP O2 1/ 2 O2 (a) Uncontrolled reaction (b) Cellular respiration NADH 50 • 2. electron transport is a fall in energy during each step to control release of fuel energy 2 e– NAD+ FADH2 2 e– 40 FM N Ι FAD FAD Fe•S Fe•S ΙΙ Q ΙΙΙ Cyt b 30 Multiprotein complexes Fe•S Cyt c 1 I V Cyt c Cyt a 20 10 0 Cyt a 3 2 e– (from NADH or FADH2) 2 H+ + 1/2 O2 H2O Electron Transport Chain powered by redox reactions Overview: Wiley Electron Transport: Wiley Watch the electrons BIO 231 Electron transport animation Watch the electrons • In addition to electron transfer……. • 3. H+ ions pumped out H+ gradient, a proton force • ET chain e- pumps H+ across mt membrane • H+ gradient drives ATP production • Interactive concepts • Watch the H+ ions • Mcgraw hill electron transport • Watch the H+, no audio Chemiosmosis couples energy of electron transport to ATP synthesis INTERMEMBRANE SPACE H + Stator Rotor • ATP synthase – H+ ion enters for one turn – ADP + P ATP Virtual Cell: Electron Transport Chain animation Internal rod Catalytic knob ADP + P i ATP MITOCHONDRIAL MATRIX H+ H+ H+ H+ Cyt c Protein complex of electron carriers ΙV Q ΙΙΙ Ι ΙΙ FADH2 NADH (carrying electrons from food) FAD ATP synthase 2 H+ + 1/2O2 NAD H2O ADP + P i + ATP H+ 1 Electron transport chain Oxidative phosphorylation 2 Chemiosmosis An Accounting of ATP Production by Cellular Respiration • Most energy: glucose → NADH → electron transport chain → proton-motive force → ATP = ~38 ATP total Electron shuttles span membrane CYTOSOL MITOCHONDRION 2 NADH or 2 FADH2 2 NADH Glycolysis Glucose 2 Pyruvate + 2 ATP 2 NADH Oxidative phosphorylation: electron transport and chemiosmosis Citric acid cycle 2 Acetyl CoA +2ATP Maximum per glucose: Glycolysis Cytosol 2 FADH2 6 NADH About 36 or 38 ATP + about 32 or 34 ATP Citric Acid Cycle mt Ox. Phos. mt Anaerobic respiration (no O2) Anaerobic respiration (cytoplasm) Prokaryotes Eukaryotes Generate ATP without O2 1. Glycolysis 2. Fermentation Fermentation No electron transport chain NAD+ reused in glycolysis (way to keep generating ATP without O2) Alcohol fermentation • Pyruvate + NADH ethanol + NAD+ + CO2 • Bacteria • Yeast by humans for: 2 ADP + 2 P i Glucose 2 ATP Glycolysis 2 Pyruvate 2 NAD+ 2 Ethanol (a) Alcohol fermentation 2 NADH + 2 H+ 2 CO2 2 Acetaldehyde Lactic acid fermentation Pyruvate + NADH lactate + NAD+ • Bacteria, fungi in cheese making • Human muscle cells use lactic acid fermentation to generate Pyruvate + NADH lactate + NAD+ • ATP when O2 is low. 2 ADP + 2 P i Glucose 2 ATP Glycolysis 2 NAD+ 2 Lactate (b) Lactic acid fermentation 2 NADH + 2 H+ 2 Pyruvate Fermentation (no O2) vs. Aerobic Respiration • Both use glycolysis to oxidize glucose (and other organic fuels ) to pyruvate • ATP – Cellular respiration 38 ATP per glucose – Fermentation 2 ATP per glucose • Obligate anaerobes – fermentation – cannot survive in the presence of O2 – Ex. clostridium botulinum • Facultative anaerobes – Yeast and many bacteria – can survive using either fermentation or cellular respiration (pyruvate can be used either way) – Ex. E. coli, Streptococcus Facultative anaerobe Glucose CYTOSOL Glycolysis Pyruvate No O2 present: Fermentation Ethanol or lactate O2 present: Aerobic cellular respiration Acetyl CoA MITOCHONDRION Citric acid cycle The Evolutionary Significance of Glycolysis • Glycolysis occurs in nearly all organisms • Glycolysis probably evolved in ancient prokaryotes before O2 on planet Glycolysis and the citric acid cycle connect to other metabolic pathways The Versatility of Catabolism • Glycolysis and fuel – Carbohydrates – many accepted – Proteins amino acids; glycolysis or the citric acid cycle – Fats glycerol glycolysis – Fatty acids acetyl CoA – An oxidized gram of fat produces >2X ATP as oxidized gram of carbohydrate Proteins Carbohydrates Amino acids Sugars Fats Glycerol Glycolysis Glucose Glyceraldehyde-3- NH3 P Pyruvate Acetyl CoA Citric acid cycle Oxidative phosphorylation Fatty acids Fermentation and anaerobic respiration enable cells to produce ATP without the use of oxygen • Most cellular respiration requires O2 to produce ATP • Glycolysis can produce ATP with or without O2 (in aerobic or anaerobic conditions) • In the absence of O2, glycolysis couples with fermentation or anaerobic respiration to produce ATP Regulation of Cellular Respiration via Feedback Mechanisms • Feedback inhibition is the most common mechanism for control • If ATP concentration begins to drop, respiration speeds up; when there is plenty of ATP, respiration slows down • Control of catabolism is based mainly on regulating the activity of enzymes at strategic points in the catabolic pathway Biosynthesis (Anabolic Pathways) • The body uses small molecules to build other substances • These small molecules may come directly from food, from glycolysis, or from the citric acid cycle