How does the cell produce ATP Substrate level phosphorylation Oxidative phosphorylation NAD FAD are Coenzymes Coenzymes Are small organic molecules They act by accepting electrons from an enzymatic reaction and transferring those electrons to a different reaction NAD nicotinamide adenine dinucleotide Is derived from niacin vitamin B3 NAD 2H NADH H1 FAD flavin adenine dinucleotide Is derived from riboflavin Vitamin B2 FAD 2H FADH2 Overview of glucose oxidation The molecule is being split Glycolysis Energy produced 4 ATP Energy spent 2 ATP Net energy gained 2 ATP Other molecules obtained 2NADH 2 Pyruvate The Krebs Cycle In bacteria and archae the Krebs cycle occurs in the cytoplasms In eukaryotes the pyruvate produced during glycolysis is transported to the mitochondria How pyruvate enters the matrix An active transport protein called pyruvate carrier carry the pyruvate molecule to the matrix This active transport protein is located in the inner membrane of mitochodrion Pyruvate is first converted to Acetyl CoA Co enzyme A acts by accepting and transferring an acetyl group COCH 3 to a substrate The A in CoA stand for acetylation Acetyl group is often bounded to a sulfur S atom Lets see the Krebs cycle NADH CO2 NADH CO2 CO2 NADH Krebs Cycle NADH 1 ATP 4 NADH 1 FADH2 3 CO ATP What the cell earns from the Krebs cycle 1 ATP molecule 4 NADH molecules 1 FADH2 molecule 3 CO2 molecules These amounts must be multiplied by 2 Why Because during Glycolysis two molecules of pyruvate are produced Summary of Glucose Oxidation What has the cell obtained from each molecule of glucose 10 molecules of NADH 2 molecules of FADH 4 ATPs The ATP molecules obtained in the oxidation of glucose are the result of substrate level phosphorylation What happens to the NADH and FADH molecules produced NADH and FADH2 carry electrons that are going to drive the redox reactions that will result in the production of a high amount of ATP molecules The electrons that they carry will be transferred to the electron transport chain in which oxygen will be the final electron acceptor molecule producing water Drops in free energy are couple with the production of ATP NADH FADH2 During glycolysis and the Krebs cycle the free energy of previous compound involves drops Sometimes it drops in small step they a couple with the production of ATP Other times it drops in large steps its couple with the production of NADH and FADH2 What will happen if the final acceptor oxygen is not present in the cell If oxygen is not present in the cell cellular respiration can t occur Instead an alternative pathway called fermentation reactions takes over Using poisons researchers figured out the sequence of the molecules in the electron transport chain NADH donate an electron to a flavin containing protein FADH2 donates its electrons to an iron sulfur containing protein that passes it directly to Q Electron Transport Chain is composed of four large protein complexes and cofactors flavin group iron sulfur heme ubiquinone Protons are pumped by three of the complexes Q and protein cytochrome c acts as shuttles that transfer electrons between complexes Electron Transport Chain is composed of four large protein complexes and cofactors http vcell ndsu nodak edu animations etc movie htm C Users Angel Desktop chapter26 Animation electron transport and swf ATP Synthase Chemiosmosis http vcell ndsu nodak edu animations atpgra dient movie htm Cellular Respiration Fermentation How fermentation occurs in humans In humans fermentation produce lactic acid In the fungus Saccharomyces cerevisiate yeast alcohol fermentation occurs
View Full Document
Unlocking...