Cellular Respiration & Glycolysis SBI4U PDF

Cellular Respiration & Glycolysis Cellular Respiration  Cellular Respiration a metabolic process (series of reactions catalyzed by enzymes) by which energy from glucose is used for ATP production. used by animals, plants, fungi, protists AND prokaryotes! aerobic r...

Cellular Respiration & Glycolysis Cellular Respiration  Cellular Respiration a metabolic process (series of reactions catalyzed by enzymes) by which energy from glucose is used for ATP production. used by animals, plants, fungi, protists AND prokaryotes! aerobic respiration: oxygen requiring process complementary to photosynthesis 3  Reactions of Cellular Respiration 1. redox reactions producing CO2 2. O2 is the last oxidizer (final electron acceptor) 3. electrons transported to O2 4. O2 combines with H+ to produce H2O 5. Coupled reactions drive ATP synthesis 4  Processes of Cellular Respiration 1. Glycolysis 2. Pyruvate oxidation 3. TCA cycle 4. Oxidative phosphorylation Occurring in different locations within cells and organelles 5 Overview of Cellular Respiration Video 6  Aerobic Respiration Four Stages Location 1. Glycolysis Cytoplasm 2. Pyruvate Oxidation Mitochondrial Matrix 3. Citric Acid Cycle Mitochondrial Matrix (aka tricarboxylic acid (TCA) cycle, aka Krebs cycle) 4. Electron Transport Chain & Inner Mitochondrial Oxidative Phosphorylation Membrane 7  Mitochondria: where it all happens, well…most of it Eukaryotic endosymbionts Very similar to eubacteria mtDNA Origin of mitochondria by intracellular enslavement of a photosynthetic purple bacterium - PMC. 8 Redox Reactions & Electron Transfer Cellular Respiration Oxidation of Glucose Example of a Redox Reaction 10  Controlled Oxidation series of enzyme-catalyzed reactions. cells capture more of the available energy as chemical potential energy and not heat energy net energy changes are the same. 11  Redox Couples Redox couples: pairs that behave like conjugates one is the reducing agent while the other is the oxidizing agent appearing on both sides of the equation Imagine who will oxidize and who will reduce when combining Fe3+ & Cu….. 12  Redox Couples Redox couples: noticing that Fe3+ is the stronger oxidizer and Cu is the stronger reducer we can imagine how each would transfer electrons 2Fe3+ + 2e- → 2Fe2+ Cu → Cu2+ + 2e-... 2Fe3+ + Cu → 2Fe2+ + Cu2+ 13  Energy Carriers Dehydrogenases: enzymes that transfer H+ and 2 electrons from donor (the oxidized) to an acceptor (the reduced) coenzyme NAD+ (nicotinamide (niacinamide, niacin = vit B3 ) adenine dinucleotide) reduced to NADH (“redox couple”) for oxidoreductases NADH used to drive redox reactions during ATP synthesis 14  Aerobic Respiration aka Cellular Respiration Aerobic: when O2 is available C6H12O6 + 6O2 ➝ 6CO2 + 6H2O ΔG = -2870 kJ/mol (complete combustion) not what is harnessed by ATP maximum of 1178 kJ/mol → theoretical max of 38 ATP may be formed through aerobic respiration 41% efficient transfer of chemical energy from glucose to ATP 15  Anaerobic Respiration Anaerobic: when O2 is not available (fermentation: enzyme driven catabolic reactions in the absence of oxygen) Alcohol fermentation (in yeast) C6H12O6 ➝ 2 CH3CH2OH + 2 CO2 (ethanol) Lactic acid fermentation C6H12O6 ➝ 2C3H6O3 (lactic acid) 16  Glycolysis Stage 1 | Cellular Respiration  Glycolysis Stage 1 | Cellular Respiration takes place in the cytosol 18  Glycolysis hydrolysis of 1 glucose molecule (6 carbons) → two pyruvate molecules (3 carbons). net gain of 2 ATP and 2 NADH 19  Key Enzymes in Glycolysis enzymes catalyzing the transfer of hydrides (H– , H+ + 2 e–) from molecule (aka dehydrogenation, a type of Dehydrogenases redox reaction). enzymes catalyzing the rearrangement of the atoms in the substrate into another isomer (aka Isomerases isomerization). enzymes catalyzing the transfer of a phosphate Kinases group from ATP to a substrate (aka phosphorylation). enzymes catalyzing the breaking down of a substrate by means other than hydrolysis or oxidation (aka Lyases lysis). 20  Phases of Glycolysis 1. Energy Consumption Phase : Two phosphorylations (by kinases): - glucose → glucose 6 phosphate, - fructose 6 phosphate → fructose 1, 6 bisphosphate 2. Energy Production Phase (x2/glucose) : one NAD+ reduced → NADH (by dehydrogenase) two ADP recharged → ATP (by kinases) 21  Glycolysis Overview investment phase pay-off phase 22 Substrate-Level Phosphorylation ADP → ATP by transfer of phosphate from a substrate to ADP Occurs in: Glycolysis Citric Acid Cycle Not during Oxidative Phosphorylation 23  Summary: Glycolysis Glucose is broken down to produce 2 pyruvate molecules Nets 2 ATP molecules 2 used and 4 recharged 2 NADH molecules recharged 24  Summary: Glycolysis Investment Phase requires 2 ATP Pay-Off Phase nets 2 ATP, 2 NADH 25 Glycolysis Review Video 26 Glycolysis Review Video 27 Glycolysis Reactions Video 28