CELLULAR RESPIRATION - P Bio PPT slides/cellular respiration .pdf · 2/18/2013 1 CELLULAR RESPIRATION…

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<ul><li><p>2/18/2013 </p><p>1 </p><p>CELLULAR RESPIRATION </p><p>Cellular Respiration </p><p>complex process whereby cells make ATP by breaking down organic </p><p>compounds </p><p> many rxns in aerobic respiration are redox: (one reactant is oxidized </p><p>while another is reduced) </p><p>location: mitochondrial cristae </p><p>Glycolysis (Glucose/breaking) </p><p>Process where one molecule of GLUCOSE (6 C) is broken </p><p>down into 2 molecules of PYRUVIC ACID(PYRUVATE) (3C) </p><p> - occurs in cytoplasm </p><p> - occurs before respiration or fermentation </p><p> - occurs in the absence of oxygen </p><p>Glycolysis: 4 Major Steps </p><p>1. glucose is phosphorylated by 2 ATP </p><p> (stable glucose glucose 6 phosphate [reactive compound] ) </p><p> *** uses 2 ATP *** </p><p>2. glucose 6 phosphate breaks down into 2 PGAL (3 C) </p><p>3. phosphate group is added to each PGAL </p><p>H ions are removed </p><p>H picked up by NAD+ </p><p>Since 2 PGAL formed2 NADH formed </p><p>(coenzyme- elec. Acceptor) </p><p>4. phosphate bonds in step 3 broken </p><p>PGAL converted to PYRUVIC ACID </p><p>*** 2 ATP generated for each PGAL *** </p><p> *** TOTAL 4 ATP *** </p><p>End products </p><p> 2 pyruvic acid (pyruvate), 2 NADH + net gain of 2 ATP </p><p> (2 used, 4 generated ) </p></li><li><p>2/18/2013 </p><p>2 </p><p>2 Possible Pathways for 2 Pyruvic Acid </p><p>If O2 present If no O2 present </p><p> respiration fermentation </p><p> (aerobic) (anaerobic respiration) </p><p>mitochondria cytosol </p><p>If no oxygen is present the 2 pyruvic acid will </p><p>go into anaerobic respiration (fermentation) </p><p>FERMENTATION </p><p>1. Lactic Acid Fermentation (animals) </p><p> A. As O2 is comsumed in aerobic respiration, it becomes scarce </p><p> B. Without O2 </p><p> - NADH (nicotinamide adenine dinucleotide) is oxidized and donates its H to pyruvic acid </p><p> C. resultant NAD returns to glycolysis where it is reduced to NADH </p><p> (cyclical- happens over and over again) </p><p> D. lactic acid forms from pyruvic acid which causes muscle pain and soreness ( muscle cells cytosol becomes acidic) </p><p>**eventually diffuses into liver where it is converted back to pyruvic acid when </p><p>O2 again present ** </p><p>2. Alcoholic Fermentation (yeasts, plant cells, microorganisms) </p><p> - converts pyruvic acid to ethyl alcohol </p><p> A. CO2 molecule is removed from Pyruvic acid (3C) leaving a 2 C compound </p><p> B. 2 H (from NADH + H ion) are added to 2C compound to form </p><p> ethyl alcohol </p><p> C. NAD is formed (back to glycolysis) </p><p> ***causes alcohol in beer and wine, air bubbles in bread, beer, and </p><p> wine***** </p><p>NO ATP FORMED IN </p><p>FERMENTATION </p><p>PURPOSE OF FERMENTATION: </p><p>TO REGENERATE NAD FOR </p><p>GLYCOLYSIS </p><p>Efficiency of Fermentation </p><p> - measured in kilocalories (1 kcal = 1000 calories) </p><p> - complete oxidation of glucose releases 686 kcal </p><p> - production of ATP from ADP uses 12 kcal </p><p> - 1 glucose molecule makes 2 ATP from glycolysis </p><p> Efficiency = ____energy required to make ATP_____ x 100% </p><p> energy released by oxidation of glucose </p><p> = 2 (ATP from glycolysis) x 12 kcal (used) x 100% </p><p> 686 kcal </p><p> = 3.5% (this is the amount of energy from complete oxidation </p><p> of glucose) </p><p> *** contains almost as much energy as original glucose molecule*** </p><p> - Anaerobic pathways only provide enough energy for unicellular and very </p><p> small multicellular organisms which have limited energy requirements </p><p> - Anaerobic pathways are very inefficient </p><p>RESPIRATION (aerobic) </p><p>C6H12O6 + 6 O2 6 H2O + 6 CO2 + 36 ATP </p><p>Process of breakdown of pyruvic acid in the </p><p>presence of oxygen </p><p> - prokaryotic cells: occurs in cytosol </p><p> - eukaryotic cells: occurs in mitochondria </p><p> - much more efficient than anaerobic respiration </p><p>2 Major Stages of Respiration </p><p> 1. krebs cycle </p><p> - oxidation of glucose is completed </p><p> - NAD+ is reduced to NADH </p><p> 2. electron transport chain </p><p> - NADH is used to make ATP via oxidative phosphorolation </p><p> - location where most ATP is made </p></li><li><p>2/18/2013 </p><p>3 </p><p>- process of extracting ATP from </p><p>NADH and FADH2 </p><p>- also known as </p><p> oxidative phosphorylation </p><p>- cytochromes: proteins that act </p><p>as carriers in ETC </p><p>Efficiency of Aerobic Respiration </p><p>efficiency of </p><p>aerobic = energy required to make ATP______ x 100% </p><p>respiration energy released by oxidation of glucose </p><p> = 38 x 12 kcal x 100% </p><p> 686 kcal </p><p> = 66% </p><p>**** aerobic respiration is almost 20 X more efficient </p><p>than glycolysis alone**** </p><p>Alternative Energy Sources </p><p>What if the body runs out of sugar for glycolysis? Can the </p><p>body still make ATP? </p><p>YES </p><p>This is how the Atkins and South Beach diets work. </p><p>They are low carb, high protein/fat diets. </p><p>Alternative Energy Sources </p><p>Fats as fuel: </p><p> - Triacylglycerol reserves tend to be stored in adipose cells </p><p> - Lipases are released into the bloodstream and break down fats in the bloodstream (from the fats and oils we eat) or travel to adipose cells. </p><p> - Lipases break the glycerol head away from the fatty acids </p><p> - Glycerol is converted to PGAL, and enters cellular respiration in the cytoplasm </p><p> - The fatty acid tails are converted to Acetyl CoA and enter the Krebs cycle in the mitochondria </p><p>Result: Still ~32-38 or so ATPs, but from fats, not glucose! </p><p>Alternative Energy Sources </p><p>Proteins as fuel: </p><p> - Excess proteins in our diets cannot be stored like glycogen or fats can, and must be broken down by the body </p><p> - Proteases break the peptide bonds of proteins back down to amino acids </p><p> - Most of the amino acid can be rearranged in cells to enter cellular respiration either as pyruvate, as acetyl CoA, or directly into the Krebs cycle </p><p>Result: Still ~32-38 or so ATPs, but from proteins, not glucose! </p></li><li><p>2/18/2013 </p><p>4 </p><p>Remember... </p><p>photosynthesis and respiration are exact </p><p>opposite processes. </p><p>Look at the general equations for both..what do you notice? </p><p>6 CO2 + 6 H2O + light energy C6H12O6 + 6 O2 </p><p>C6H12O6 + 6 O2 6 H2O + 6 CO2 + 36 ATP </p><p>Both are needed for all of lifes activities. </p><p>Study for the test !!! </p></li></ul>


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