ecture 14 10/3/05 ellular Respiration: arvesting hemical Energy hapter 9 II. atabolic Pathways Lecture utline 1. Review Fatty Acid xidation Pathway. xidation of Monosaccharides ( Pathway) 3. Mitochondrial Spaces: Matrix, Intermembrane Space 4. xidation of 5. omplete oxidation of arbon from FA ox & glycolysis TA ycle (Kreb s ycle) 6. ashing in the accumulated Reducing Equivalents - Phosphorylation 1 atty Acid xidation (β-oxidation)( in Mitochondria Priming Step Saturated hydrocarbon Net Result of Fatty Acid xidation Pathway Fatty shortened by carbon unit -steps down oxidation states of carbon -captures Reducing potential NADH + H + FADH e- H+ Ester () Ketone unsaturated hydrocarbon alcohol e- H+ removed 3 carbon attached to (acetyl ) xidation of arbon -H - to = to S apture reducing equivalents NADH + H + FADH 4
lycolysis Another catabolic pathway consists of two major phases Energy investment phase xidation of monosaccharides olysaccharides digested to monosaccharides; no energy harvested) Energy investment phase (Priming Steps) + P used exoses (like glucose) carbon sugar ldehyde with 5 alcohols Energy payoff phase Energy payoff phase 4 ADP + 4 P 4 formed NAD + + 4 e - + 4 H + H+ NADH + (Two) 3 carbon with a ketone 5 oxidized to pyruvic Net Harvest f Pathway Figure 9.8 + H + H 4 formed used + H + NAD + + 4 e + 4 H + NADH 6 Energy Priming Stage Add P i to #6 carbon Split into two 3 carbon units Rearrange Add P i to #1 carbon H H H H H H H H H H H ADP H H P H H H H H H H H -6-phosphate H P H H H H H H H H Fructose-6-phosphate ADP HH H rearrange H H P Substrate Level Phosphorylation Dihydroxyacetone Glyceraldehyde- 7 8 P H H P H H H H H Fructose- 1, 6-bisphosphate 4 Aldolase P H 1 Hexokinase 3 Phosphoglucoisomerase Phosphofructokinase 5 H Isomerase of these Energy PAYFF Stage xidize #1 aldehyde to Acid NADH + H +, high energy phosphate Harvest Phosphate Substrate Level Phosphorylation made rearrange xidize # alcohol to Ketone High energy phosphate Harvest Phosphate Two f these pyruvate NAD + NADH + H + P 6 Triose phosphate dehydrogenase P i HH H P 1, 3-Bisphosphoglycerate ADP 7 Phosphoglycerokinase HH H P 3-Phosphoglycerate 8 Phosphoglyceromutase H P H H -Phosphoglycerate 9 H Enolase P H Phosphoenolpyruvate ADP 10 kinase
et Result of Pathway Fate of the molecules? 6 arbon Sugar oxidized to TW ( with ketone) et yield of produced by substrate level enter the mitochondrion for further oxidation produce 6 Pathway called the TA apture reducing equivalents NADH + H + What does it mean to get into the mitochondrion? 9 occurs in cytosol 10 Mitochondria Functional Spaces Matrix Inner Mito Membrane Electrons carried via NADH Glycolsis Electrons carried via NADH and FADH : electron transport and chemiosmosis Folds of ner membrane alled ristae uter Mitochondrial Membrane Intermembrane Space 11 Figure 9.6 ytosol Substrate-level Mitochondrion Substrate-level 1
Matrix ontains DNA ontains bacterial-like ribosomes Site of three important oxidative reaction s Fatty Acid xidation oxidation TA ycle ntermembrane Space Reservoir to hold H+ ions xidation of to Acetyl YTSL NAD + NADH + H + MITHNDRIN Familiar? S nner Mitochondrial Membrane Densely packed with proteins Site of oxidative H 3 pyruvate Transport protein electron transport and production13 14 Figure 9.10 1 oenzyme A 3 H 3 Acetyl Acetyl Proteins arbohydrates Fats Digestion xidation Amino s Sugars Glycerol Fatty s Glyceraldehyde-3- P atabolic Pathways Tri arboxylic Acid TA ycle Kreb s ycle NH 3 Acetyl Interconnected Pathways ommon 15 16
How? 19 0 TA ycle tepping down the xidation Series of arbons -Acid to -Ketone to (thioester) - saturated to unsaturated - unsaturated to alcohol - alcohol to ketone or carboxylic - decarboxylation apture reducing equivalents NAD + e - + H + NADH + H + FAD e - + H + FADH 17 TA ycle xidize the carbon unit Acetyl To Five key oxidation steps 3 NADH + H + 1 FADH 1 GTP Per carbon unit Regenerate the initial 4 carbon repeat (from glycolysis, molecules per glucose) Figure 9.11 FADH NADH + 3 H + FAD Acetyle ADP + P i 18 phosphorylatio 3 NAD + 3 NADH + 3 H + eactions of the TA pathway What good are accumulated reducing equivalents? ote oxidation points apture of 3 NADH + H + apture of 1 FADH apture of 1 high energy phosphate bond (GTP) per carbon unit H = e- H + H + = H + BM! Free energy, G H + 1 / Explosive release of heat and light energy o some GTP harvested, ut a lot of reducing equivalents accumulated these are worth a lot more Figure 9.5 A H
The Regeneration Energy arriers Energy carriers (, NAD +, FAD) present in only minute amounts ly limited amounts of reducing equiv carriers must cash them in - oxidize them ectron transport oxidizes NADH and FADH back to NAD + and FAD e - H + aptured in catabolism Energy from catabolism (exergonic, energy yielding processes) NADH + H + NAD + e - H + ashed in Energy for cellular work (endergonic, energyconsuming processes) 1 Mitochondrial Functions xidize compounds to + H Fatty xidation Produce xidation of reduced carriers TA Kreb s ycle NADH & FADH Generate >90% of Typical ell s Phosphorylation electron transport synthesis xidize reduced carriers to produce or equiv Next time How cash in the NADH + H+ and FADH poker chips for Phosphorylation Summary -FA oxidation in matrix of mitochondrion - (ox of sugar) in cytosol -xidation of pyruvate in matrix of mitochondrion -TA (oxidation of acetyl ) in matrix - accumulate reducing equivalent carriers - must cash in for oxidative Phosphorylation Electrons carried via NADH Electrons carried via NADH and FADH Glycolsis ytosol Mitochondrion 3 4