Chemiosmosis ADP -> ATP Concentration Gradient (Potential Energy = [H+] Relation to Electron transport chain Figure 6.7

Substrate-level Phosphorylation Phosphate group transferred to ADP from substrate (FORM ATP!!!) ATP production, but is small % in cell.

Systematic oxidation of organic compounds to release energy May be anaerobic, i.e. in the absence of oxygen, or… Aerobic, requiring oxygen. Cellular Respiration

Oxidation is the loss of electrons Reduction is gain of electrons.. Oxidation and reduction always happen together… Remember electronegativity (ability to “grab” electrons: O > N > C > H) Redox Review

Methane is a saturated hydrocarbon. When burned it is oxidized and energy is given off. The overall equation is: Oxidation of Methane

Oxidation States of the central carbon atom...

Energy contained in the molecule….

Glucose Oxidation Glucose (Other organic molecules) broken down / rearranged to gain energy from within bonds. C6H12O6 + 6O > 6 CO2 + 6 H2O + ATP (ENERGY)

Energy Use within the Cell Cellular respiration “dismantles” glucose in a series of steps. Energy from organic molecules (I.e. glucose) is harvested from the chemical bonds within the molecule. Electrons are “shuttled” through a series of energy-releasing reactions.

Glucose loses H+ (Conversion to CO2) Oxygen gains H+ (Conversion to Water) H+ movements represent electron transfers.

Key Players in Redox Rxns Dehygrogenase = enzyme NAD+ (nicotinamide adenine dinucleotide) = coenzyme Both remove H atoms (& electrons) - - function as oxidizing agents.

The total oxidation of glucose will yield the same products as the total oxidation of methane... Oxidation of Glucose

Mitochondrion Graphic downloaded from - Outer membraneMatrixCristae Not visible: 1) Inner membrane, 2) Intermembrane space

ABOVE: Anaerobic respiration (in this case, alcoholic fermentation) BELOW: Aerobic respiration. Aerobic vs. Anaerobic 38 ATPs 2 ATPs

Locations of Cellular Respiration Processes

ATP Phosphorylation NAD Reduction ATP is a nucleotide NAD is a dinucleotide Both are formed in the process of aerobic respiration Eventually all usable energy must be stored in ATP

ATP - Phosphorylation

ATP - readily available chemical energy Nicotinamide Adenine Dinucleotide - stores energy, but not readily available energy ATP - NAD

NAD gains energy when reduced Electrons are always accompanied by hydrogens... NAD - redox

Aerobic Respiration - Overview

GLYCOLYSIS (Exergonic) All living things follow the same steps in the initial breakdown of glucose (C 6 ) to pyruvic acid (pyruvate) (C 3 ). Some stop there, realizing 2 ATP in energy, others proceed further and realize as much as 38 ATP.

Respiration FlowChart 6O 2 Glycolysis C > C 3 C 6 H 12 O 6 Electron Transfer System Krebs (C.A.) Cycle C > C Oxid. of Pyruvate C > C 2 ATPCO 2 NADH H 2 O FADH

OXIDATION of PYRUVATE In the process of glycolysis, one molecule of glucose produces two molecules of pyruvate. All living things perform glycolysis. Some anaerobically convert pyruvate to ethyl alcohol, and others convert it to lactate.

The Aerobic Pathway Production of NADH Product is more oxidized than pyruvate

The Krebs Cycle (Citric Acid Cycle)

Entry of Acetyl CoA into Cycle

Citrate to Isocitrate

Isocitrate to Ketoglutarate

Ketoglutarate to Succinate

Succinate to Fumarate

Fumarate to Malate

Malate back to Oxaloacetate

Respiration Flow Chart

Electron Transport Chain

Reduction of NAD + to NADH + H + NAD is a molecule that can be reduced by electrons that have been oxidized away from the carbon substrates… NADH, in turn, can be oxidized and some other molecule reduced with its electrons...

Reduction of the next electron acceptor, FMN NADH yields its electrons and Hydrogen ions to FMN (Flavin Mononucleotide) FMNH then can be oxidized and pass the electrons on to the next acceptor...

Electron Transport Chain as the electrons are passed on energy is lowered… enough energy is transformed to make three ATPs for each reduced NADH… the final electron acceptor is oxygen

What about FADH 2 ? FADH2 has less energy than NADH it passes its electrons directly to Coenzyme Q, skipping one ATP step...

ATP Arithmetic This chart is on page 9-2 of the A.P. Bio Study Guide

Chemiosmosis

The Mitochondrion Smooth outer membrane Folded inner membrane Inner folds are called cristae. Carrier molecules embedded in cristae. OUTER MEMBRANE INNER` MEMBRANE CRISTA INTER- MEMBRANOUS SPACEMATRIX

Active Transport Electrons (and hydrogens) build up in matrix

Active Transport As electrons are transported, H’s are pumped into IMS.

Eventually a high chemiosmotic gradient of protons develops.

The only way for H + to return is through ATP synthetase.

ATP Synthetase As H + ’s move through ATP synthetase, ATP is formed in the matrix. ATPADP