Transcript Slide 1
In Animals In the presence of oxygen pyruvate is transported into the mitochondria where it enters the next major metabolic pathway for the production of ATP energy. The citric acid cycle. Aerobic. If there is no oxygen present then the pyruvate is converted to a substance called lactate. • The Electron Transport Chain and Proton Pumping • Chemiosmotic Phosphorylation • Imbedded in the inner mitochondria membrane are a series of electron carriers. These electron carriers pass electrons from NADH and FADH to one another down a red-ox stairway. The net result of this series of step-wise electron exchanges is to pump H+ (protons) out of the matrix into the outer compartment between the outer and inner membrane of the mitochondria. • This process establishes a steep proton gradient across the inner mitochondrial membrane. This creates a great deal of potential energy across the inner membrane. • This potential energy can be harnessed by an enzyme system to form ATP from ADP + Pi. This is known as chemiosmotic phosphorylation. • For each 2H+ 1 ATP is created. Therefore since each NADH causes 6 H+s to be pumped out 3 ATP can be made for each NADH entering the respiratory chain. • Also each FADH2 can pump 4 H+s. Therefore each FADH2 can cause 2ATP to be made. • Glucose is not the only material that can be metabolized to generate energy. Many carbohydrates can be broken down in glycolysis and enter the Krebs Cycle. Proteins can be broken down into amino acids and those can be deaminated and the carbon chains feed into the Krebs Cycle. The very long carbon chains of fatty acids can be chopped into two carbon pieces by a process known as Beta Oxidation. Since the fatty acid chains can be up to 20 carbons long there is a very great deal of energy stored in fats.