Cellular Respiration :Cellular Respiration BIOLOGY


Cellular Respiration :Cellular Respiration A cellular process that requires oxygen and gives off carbon dioxide. Carbohydrates, fats, and proteins can be used as energy sources. Most often involves breaking down glucose to make CO2, H2O, and ATP. Catabolism breaks down molecules that can also be used for anabolism to build other compounds.


Glycolysis :Glycolysis Energy within a glucose molecule is released slowly so that ATP can be produced gradually. 2 ATP used to activate glucose that splits into PGAL. Substrate-Level Phosphorylation Oxidation of PGAL results in four high-energy phosphate groups, making four ATP. NAD+ and FAD are oxidation-reduction enzymes active during cellular respiration.


Substrate-level Phosphorylation :Substrate-level Phosphorylation


Inside the Mitochondria :Inside the Mitochondria End product of glycolysis, pyruvate, enters the mitochondria, where it is oxidized to carbon dioxide during the transition reaction and citric acid cycle.


Conversion of pyruvate to acetyl CoA, the junction between glycolysis and the Citric Acid cycle :Conversion of pyruvate to acetyl CoA, the junction between glycolysis and the Citric Acid cycle


Transition Reaction :Transition Reaction Connects glycolysis to the citric acid cycle.


Citric Acid Cycle :Citric Acid Cycle Originally called Krebs cycle.


A summary of the Krebs cycle :A summary of the Krebs cycle For each molecule of Acetyl CoA, the Citric Acid Cycle produces 2 ATP and 2 CO2 molecules. Has 8 steps with 8 different enzymes.


Electron Transport System :Electron Transport System As electrons pass down the electron transport system, energy is captured and ATP is produced. Oxidative phosphorylation refers to the production of ATP as a result of energy released by the electron transport system. The total of 32-34 ATP produced by ETS is calculated by allowing 3 ATP per NADH and 2 ATP per FADH2 that enter the ETS.


NAD+ as an electron shuttle :NAD+ as an electron shuttle


Figure 9.5 An introduction to electron transport chains :Figure 9.5 An introduction to electron transport chains


Chemiosmosis couples the electron transport chain to ATP synthesis :Chemiosmosis couples the electron transport chain to ATP synthesis Yellow arrow = electron flow Red arrow = proton flow to form ATP


Figure 9.14 ATP synthase, a molecular mill :Figure 9.14 ATP synthase, a molecular mill


Slide 15:Cellular Respiration Summary


Control of Cellular Respiration :Control of Cellular Respiration The important switch in the control of respiration is the enzyme phosphofructokinase. This enzyme catalyzes step 3 of glycolysis. Phosphofructokinase is inhibited by ATP and stimulated by ADP or AMP. It is also inhibited by citric acid. This synchronizes the rates of glycolysis and the Krebs Cycle.


Fermentation :Fermentation Glycolysis followed by reduction of pyruvate by NADH to either lactate or alcohol and carbon dioxide. Anaerobic pathway. Can provide rapid burst of ATP. Lactic Acid Fermentation is common in muscle cells.


Fermentation :Fermentation Alcohol--yeast produce wine and beer and cause bread to rise. Lactic Acid—bacteria produce yogurt, sauerkraut, cheese. Also in muscle cells when working anaerobically.


Comparison of Cellular Respiration versus Fermentation :Comparison of Cellular Respiration versus Fermentation One mole of glucose yields 686 kcal in a colorimeter. Cellular respiration has a yield of about 263 kcal. 263/686 = 38% of available energy is used. What happened to the rest? Fermentation yields only 2 ATP or about 15/686 or 2% of available energy.


Figure 9.2 A review of how ATP drives cellular work :Figure 9.2 A review of how ATP drives cellular work