THE CELLULAR RESPIRATION SAGA: Glycolysis, Fermentation & Pyruvate Oxidation

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1 THE CELLULAR RESIRATION SAGA: Glycolysis, Fermentation & yruvate Oxidation 1 HOW DO WE GET AT? AT is a product of cellular respiration O Breathing CO Breath in O O diffuses into bloodstream Lungs O diffuses into cells through the plasma membrane O Transported in bloodstream CO Muscle cells carrying out Cellular Respiration 1

2 CELLULAR RESIRATION Oxygen molecules diffuse across the plasma membrane into the cell, then into the mitochondria O CO 3 CELLULAR RESIRATION MANY steps result in products necessary to live C 6 H 1 O 6 6 O 6 CO 6 AT Heat *Glucose Oxygen Carbon dioxide Water *Glucose is the preferred molecule for respiration, but we can use other types also 4

3 CELLULAR RESIRATION Only about 34% of energy from glucose is transferred to AT C 6 H 1 O 6 6 O 6 CO 6 AT Heat Glucose Oxygen Carbon dioxide Water Reactants otential energy Energy roducts Amount of energy released 5 LAYERS OF CELLULAR RESIRATION rocesses of oxidation and reduction (redox reactions) OXIDATION is the loss of electrons from a substance REDUCTION is the addition of electrons to a substance 6 3

4 LAYERS OF CELLULAR RESIRATION NAD + is a coenzyme that accepts electrons and shuttles them around Coenzyme Organic molecule made from niacin (vitamin B3) Take your vitamins! NAD+ Some molecule with yummy electrons 7 LAYERS OF CELLULAR RESIRATION NADH can hold two electrons Becomes oxidized + H Becomes reduced + H NAD + NADH H + H + + (carries) electrons) 8 4

5 LAYERS OF CELLULAR RESIRATION Electron transport chains NAD + NADH Energy released and available for making AT 1 O H + 9 Operation: Break Down Glucose! Happens in the cytosol / cytoplasm Happens in 9 steps No OXYGEN REQUIRED hase 1: Energy Investment hase (steps 1 4) hase : Energy ayoff hase (steps 5 9) 10 5

6 Reactants at each step are products for the next step. Each step has its own enzyme(s) A Enzyme Reaction B Enzyme Reaction C Enzyme Reaction D Glucose Glucose yruvate 11 Energy Investment hase (Steps 1 4) AT AD Step 1 Glucose Less stable 6 carbon sugar Invest AT molecules to break glucose into smaller sugars AT AD 3 Even less stable 6 carbon sugar EVEN less stable 6 carbon sugar 4 Glyceraldehyde 3-phosphate 1 (G3) 6

7 Energy ayoff hase Step 5 is a redox reaction Two 3 Carbon Sugars Redox reaction NAD + NAD Inorganic hosphate NADH NADH +H + +H + Two 3 Carbon Sugars 13 Becomes oxidized + H +H Becomes reduced + H NAD + NADH H + H + + (carries) electrons) 14 7

8 Energy ayoff hase (steps 6 9) 4 AT molecules are produced by SUBSTRATE LEVEL HOSHORYLATION AT AD AD 6 6 AT AD AD 9 9 AT AT yruvate 15 SUBSTRATE LEVEL HOSHORYLATION Transferring a phosphate group directly to an AD Enzyme Enzyme AD AT Substrate (3 Carbon Sugar) roduct 16 8

9 Energy ayoff hase (steps 6 9) AT AD AD 6 6 AT AD AD 9 9 AT AT yruvate 17 Starting with glucose 4 AT s made (synthesized) AT s invested = net AT s synthesized AT AT yruvate molecules synthesized from 1 glucose No Oxygen required! NAD + s reduced to NADH s = 4 electrons banked NADH NADH 18 9

10 An ancient process that occurs in almost any living organism Glycolysis can lead to aerobic or anaerobic respiration You are here! 19 LIFE AFTER Option1: Alcohol Fermentation (EX: Yeast) Anaerobic Converting pyruvate to alcohol and CO AD + Glucose Glycolysis NAD + AT NADH Recycles NADH to NAD+ (redox) yruvate NADH CO NAD + Ethanol 0 10

11 LIFE AFTER Option : Lactic Acid Fermentation (EX: Dairy) Anaerobic Converting pyruvate to lactic acid and CO Recycles NADH to NAD+ (redox) AD + AT Glucose Glycolysis NAD + NADH yruvate NADH NAD + Lactate 1 LIFE AFTER Option 3: Continue with aerobic respiration You are here! 11

12 AEROBIC RESIRATION Next step: yruvate Oxidation in the mitochondria Mitochondrion 3 YRUVATE OXIDATION Cleans up the two pyruvates for the citric acid cycle NAD + NADH + H + CoA yruvate 1 CO 3 Coenzyme A Acetyl coenzyme A 4 1

13 COMARE OTIONS Fermentation vs. yruvate Oxidation Fermentation Follows Glycolysis Anaerobic Recycle NADH Make lactic acid or Alcohol Make CO yruvate Oxidation Follow Glycolysis Aerobic No recycling needed Make acetyl CoA (coenzyme) Make CO 5 Electrons carried by NADH FADH Glycolysis Glucose yruvate yruvate Oxidation Citric Acid Cycle Oxidative hosphorylation (Electron transport and chemiosmosis) CYTOSOL MITOCHONDRION AT Substrate-level phosphorylation AT Substrate-level phosphorylation AT Oxidative phosphorylation 6 13