Respiration The process in which organisms breakdown glucose. The energy in the chemical bonds of glucose is eventually captured in ATP molecules for use by an organism to do work C6H12O6 + 6 O2  6CO2 + 6 H2O + ATP energy Occurs in 3 major steps glycolysis Krebs cycle Electron transport system (ETS)

Redox Rx Key to transferring energy from one molecule to another Glucose  ATP As e- ‘fall’ from molecule to molecule (oxidation/reduction), energy is captured to form ATP from ADP and phosphate group Organisms use ATP as energy source to do work

glycolysis Prokaryotes and eukaryotes Occurs in cytoplasm anaerobic 10 step process Net 2 ATP (by substrate level phosphorylation) 2 NADH (nicotinamide adenine dinucleotide) 2 pyruvate (3C)

Glycolysis steps glucose  (hexokinase) and ATP  ADP Glucose 6-phosphate  (phosphoglucoisomerase) Fructose 6-phosphate  *(phosphofructokinase) and ATP  ADP Fructose 1,6-biphosphate *Allosteric enzyme inhibited By  ATP and citrate  (aldolase)

Glycolysis steps X 2 Glyceraldehyde phosphate (triose phosphate dehydrigenase) + 2 NADH + 2 H+ 1,3-diphosphoglycerate (phosphoglycerokinase) + ATP 3-phosphoglycerate  (phosphoglyceromutase) 2-phosphoglycerate (endolase) + 2 H2O

Glycolysis steps X 2 phosphoenolpyruvate ( pyruvate kinase) + ATP Final products of glycolysis = 2 pyruvate 2 NADH 2 ATP (net) Pyruvate  Krebs cycle if aerobic fermentation if anaerobic NADH + H+  ETS ATP  do ‘work’

fermentation In anaerobic conditions, pyruvate molecules are broken down in a process called fermentation Alcohol fermentation (yeast, fungi, bacteria) Products = ethanol CO2 NAD+ (recycled)

Krebs cycle In aerobic conditions, pyruvate enters the Krebs cycle (runs X2 for each glucose) In mitochondria Eukaryotes only Hans Krebs Products = 2 ATP (by substrate level phosphorylation) NADH FADH2

Krebs cycle Pyruvate converted to acetyl CoA Requires coenzyme A Gives off CO2 and NADH Acetyl CoA combines with oxaloacetic acid Forms citric acid Citric acid  isocitrate  -ketoglutaric acid  Succinyl CoA  succinate  fumarate  Malate  Oxaloacetic acid (to start cycle over)

Krebs cycle steps Krebs cycle products Oxaloacetic acid regenerated to run cycle 2 ATP to do ‘work’ 6 NADH + 6 H+  ETS 2 FADH2  ETS 6 CO2

ETS Energy in e- from NADH and FADH2 travel ‘down’ series of electron carriers in redox Rx Energy used to pump H+ from matrix to intermitochondrial space H+ diffuse through ATP synthase to make ATP (chemiosmosis) Back into matrix O2 final e- acceptor H+ + e- combine with O2 to form water Electron Transport Chain: The Movie

ETS O2 used to combine with 2H+ and 2e- to form H2O NAD+ regenerated for Krebs cycle FAD+ regenerated for Krebs cycle 32-34 ATP generated via chemiosmosis Total ATP = 2 + 2 + 34 = 38 Cellular Respiration

versatility Fat catabolism Glycerol  glyceraldehyde phosphate Fatty acids  acetyl CoA via beta oxidation Protein catabolism Amino acids  Krebs cycle after deaminated Anabolic pathways AA from Krebs Glucose from pyruvate Fatty acids from acetyl CoA