packet #28 chapter #9. summary thus far… at the end of the krebs cycle, and before the cell makes...
TRANSCRIPT
Cellular CatabolismThe Electron Transport Chain & Oxidative Phosphorylation
Packet #28Chapter #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 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 CO2
4 from the Kreb’s Cycle 2 as pyruvate is changed to ACoA
Oxidative Phosphorylation & Chemiosmosis
Oxidative Phosphorylation vs. ChemiosmosisOxidative 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
H2O. More to come later
Oxidative Phosphorylation vs. Chemiosmosis IIChemiosmosis
Also known as chemiosmotic couplingThis 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 IIIWhat is the connection between Oxidative
Phosphorylation and Chemiosmosis?In order for oxidative phosphorylation to occur,
chemiosmosis MUST be part of the process.
The Goal of the Electron Transport Chain
Goal of the Electron Transport Chain IThe 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 complexesElectron carriers and ATP synthase.
The complexes, of the electron transport chain, are used to produce large amounts of ATP
Yields of ATP1 FADH produces 2 ATP’s1 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 ChainRemember 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 IIThere 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 SynthaseAs the hydrogen
ions, resulting from the change of NADH to NAD+, are pumped across ATP synthase (Complex #5), ADP & P are changed into ATP.
Oxidative Phosphorylation at the Electron Transport Chain
Oxidative Phosphorylation at the Electron Transport Chain
Calculating the Total Amount of ATP’s per Glucose molecule
The Big Picture
Calculating the Total Amount of ATP’s per Glucose MoleculeGlycolysis
2 net ATP substrate level
phosphorylation—chemical reactions
4-6 ATP (2 NADH) (Shuttles)
Pyruvate to ACOA6 ATP (2 NADH)
Krebs Cycle2 ATP
From 2 GTP’s18 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
Drugs That Impact the Production of ATP at the Electron Transport ChainOligomycin
Drug that binds to the stalk of ATP synthase and closes the H channel
2, 4-dinitrophenolThis is an uncouplerThese increase the permeability of the inner
mitochondrial membrane to protonsCauses electron transport to proceed at a rapid rate
without the establishment of a gradientThe energy produced by the transport of electrons is
released as heat rather than being used to synthesize ATP Fever
Aspirin is an uncouplerThis is what explains fevers with overdoses
Review I
Review II
Regulation of Glycolysis/Cell Respiration
Regulation of Glycolysis/Cell RespirationRegulation is via allosteric activation or
inhibition or via the phosphorylation or dephosphorylation of rate-limiting enzymes.
Phosphofructokinase is inhibited by ATP and activated by AMPEnzyme used to make fructose 1, 6
bisphosphateInhibition by citrate
First intermediate of the Kreb’s Cycle