Cellular Catabolism The Electron Transport Chain & Oxidative Phosphorylation

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