Presentation on theme: "Packet #28 Chapter #9. Summary Thus Far… At the end of the Krebs Cycle, and before the cell makes more ATP at the electron transport chain, produced so."— Presentation transcript:
Summary Thus Far… At the end of the Krebs Cycle, and before the cell makes more ATP at the electron transport chain, produced so far is… 2 NET ATP Glycolysis 2 GTP Kreb’s Cycle Later changed to ATP 2 FADH Kreb’s Cycle 10 NADH 2 from Glycolysis See upcoming slides. 2 as pyruvate is changed to ACoA 6 from the Kreb’s Cycle 6 CO 2 4 from the Kreb’s Cycle 2 as pyruvate is changed to ACoA
Oxidative Phosphorylation vs. Chemiosmosis Oxidative Phosphorylation Process in mitochondria in which ATP formation is driven by the transfer of electrons from food molecules to oxygen. The ultimate destination of the electrons, that originated with the food molecule (glucose), is oxygen. This oxygen atom is combined with H + ions to make H 2 O. More to come later
Oxidative Phosphorylation vs. Chemiosmosis II Chemiosmosis Also known as chemiosmotic coupling This is the mechanism in which a gradient of hydrogen ions (a pH gradient), across the inner mitochondria membrane, is used to drive an energy requiring process. Examples ATP production at the electron transport chain The transport of a molecule across a membrane. Flashback to previous packet. Co-transport
Oxidative Phosphorylation vs. Chemiosmosis III What is the connection between Oxidative Phosphorylation and Chemiosmosis? In order for oxidative phosphorylation to occur, chemiosmosis MUST be part of the process.
Goal of the Electron Transport Chain I The function of the electron transport chain is to convert all of the previously made NADH and FADH into ATP. This happens via oxidative phosphorylation. The electron transport chain is located in the inner membrane of the mitochondria and is composed of 5 complexes Electron carriers and ATP synthase. The complexes, of the electron transport chain, are used to produce large amounts of ATP
Yields of ATP 1 FADH produces 2 ATP’s 1 NADH produces 3 ATP’s However, one must be mindful of what happens to the NADH entering into the mitochondria after glycolysis has occurred.
NADH, Glycolysis & The Electron Transport Chain Remember that glycolysis occurs in the cytosol of the cell. The NADH produced is in the cytosol of the cell. The NADH produced in the cytosol of the cell must enter the mitochondria via shuttles.
NADH, Glycolysis & The Electron Transport Chain II There are TWO types of shuttles used for moving the NADH produced in the cytosol into the mitochondria matrix. Glycerophosphate shuttle Changes NADH into FADH as it transported into the mitochondria Malate-aspartate shuttle NADH remains as NADH as it transported into the mitochondria
ATP Synthase As the hydrogen ions, resulting from the change of NADH to NAD+, are pumped across ATP synthase (Complex #5), ADP & P are changed into ATP.
Calculating the Total Amount of ATP’s per Glucose Molecule Glycolysis 2 net ATP substrate level phosphorylation—chemical reactions 4-6 ATP (2 NADH) (Shuttles) Pyruvate to ACOA 6 ATP (2 NADH) Krebs Cycle 2 ATP From 2 GTP’s 18 ATP (6 NADH) 4 ATP (2 FADH) In the end we have a total of 36-38 net ATPs generated.
Drugs That Impact the Production of ATP at the Electron Transport Chain Oligomycin Drug that binds to the stalk of ATP synthase and closes the H channel 2, 4-dinitrophenol This is an uncoupler These increase the permeability of the inner mitochondrial membrane to protons Causes electron transport to proceed at a rapid rate without the establishment of a gradient The energy produced by the transport of electrons is released as heat rather than being used to synthesize ATP Fever Aspirin is an uncoupler This is what explains fevers with overdoses
Regulation of Glycolysis/Cell Respiration Regulation is via allosteric activation or inhibition or via the phosphorylation or dephosphorylation of rate-limiting enzymes. Phosphofructokinase is inhibited by ATP and activated by AMP Enzyme used to make fructose 1, 6 bisphosphate Inhibition by citrate First intermediate of the Kreb’s Cycle