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

CH4 + 2O2 CO2 + 2H2O

Oxidation Statesof the central carbon atom...

O

C O

O

OHCH

CH H

O

H

Energy contained in the molecule….

REACTION

ENERGY

Glucose Oxidation

Glucose (Other organic molecules) broken down / rearranged to gain energy from within bonds.

C6H12O6 + 6O2 -------> 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

CH4 + 2O2 CO2 + 2H2O

C6H12O6 + 6O2 6CO2 + 6H2O

Mitochondrion

Graphic downloaded from - http://cellbio.utmb.edu/cellbio/mitoch1.htm

Outer membrane Matrix Cristae

Not visible: 1) Inner membrane, 2) Intermembrane space

ABOVE: Anaerobic respiration (in this case, alcoholic fermentation)

BELOW: Aerobic respiration.

Aerobic vs. Anaerobic

C6H12O6 + 6O2 6CO2 + 6H2OREDUCED OXIDIZED

38 ATPs

2C2H5OH + 2CO2C6H12O6 REDUCED OXIDIZED

2 ATPs

Cytoplasm

Mitochondrion

Locations of Cellular Respiration Processes

GLYCOLYSIS

OXIDATION ofPYRUVATE

KREBSCYCLE

ELECTRONTRANSPORT

ATP PhosphorylationNAD 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

PPPPPP

ATPP + ADP

ENERGY

ENERGY

ATP - readily available chemical energy

Nicotinamide Adenine Dinucleotide - stores energy, but not readily available energy

ATP - NAD

PPP

PP

NAD gains energy when reduced

Electrons are always accompanied by hydrogens...

NAD - redox

NAD+

ENERGY

ENERGY

NADH + H +

e- + H+

e- + H+

Aerobic Respiration - Overview

GLYCOLYSIS

OXIDATION ofPYRUVATE

KREBSCYCLE

ELECTRONTRANSPORT

2 NADH

2 NADH

2 ATP

2 ATP

2 FADH6 NADH

10 NADH2 FADH

30 ATP4 ATP

GLYCOLYSIS (Exergonic) All living things follow the same steps

in the initial breakdown of glucose (C6) to pyruvic acid (pyruvate) (C3).

Some stop there, realizing 2 ATP in energy, others proceed further and realize as much as 38 ATP.

Respiration FlowChart

6O2

GlycolysisC6 ----> C3

C6H12O6

Electron Transfer System

Krebs (C.A.) CycleC2 ----> C

Oxid. of PyruvateC3 ----> C2

ATPCO2

NADH

H2O

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

H3C

C = O

C = O

O-O

-

pyruvate

H3C

S - CoA

C = O

Acetyl CoA

CO2 S-CoA

NAD NADH

• Production of NADH

•Product is more oxidized than pyruvate

The Krebs Cycle(Citric Acid Cycle)

Entry of Acetyl CoA into Cycle

H2C

Citrate

HOC COO

COO

H2C

COO

H3C

S - CoA

C = O

Acetyl CoA

H2C

Oxaloacetate

C = O

COO

COO

S-CoA

Citrate to Isocitrate

H2C

Citrate

HOC

COO

H2C

COO

HOCH

Isocitrate

HC COO

COO

H2C

COO

H2O

COO

H2O

Isocitrate to Ketoglutarate

HOCH

Isocitrate

HC COO

COO

H2C

COO CO2 CO2

C = O

Ketoglutarate

H2C

COO

H2C

COO

NAD

NADH

Ketoglutarate to Succinate

CO2

C = O

Ketoglutarate

H2C

COO

H2C

COO

Succinate

H2C

COO

H2C

COO

NADNADH

ADPATP

Succinate to Fumarate

Succinate

H2C

COO

H2C

COO

Fumarate

HC

COO

HC

COO

FADFADH 2

Fumarate to Malate

H2O Fumarate

HC

COO

HC

COO

Malate

H2C

COO

HOCH

COO

Malate back to Oxaloacetate

Malate

H2C

COO

HOCH

COONAD

NADHH2C

Oxaloacetate

C = O

COO

COO

Respiration Flow Chart

6O2

GlycolysisC6 ----> C3

C6H12O6

Electron Transfer System

Krebs (C.A.) CycleC2 ----> C

Oxid. of PyruvateC3 ----> C2

ATPCO2

NADH

H2O

FADH

Electron Transport Chain

Reduction of NAD + to NADH + H+

NAD

NADH

H+

e 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...

OXIDIZED

REDUCED

H+

e

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...

NAD

NADH

H+

e

H+

e

FMN

FMNH

H+

e

FMN

CoQ

Ct b

Ct c

Ct a

Ct a 3

NAD

Electron Transport Chain• as the electrons are passed on energy is lowered…• enough energy is transformed to make three ATPs for each reduced NADH…ATP

ATP

ATP

H2O

O

• the final electron acceptor is oxygen

FMN

CoQ

Ct b

Ct c

Ct a

Ct a 3

NAD

What about FADH2?

H2O

O

• FADH2 has less energy than NADH• it passes its electrons directly to Coenzyme Q, skipping one ATP step...

FAD

ATP

ATP

ATP

Glycolysis

ATP's Direct from C

Pathway

NADH's Produced

Pyruvic Acid Conversion to Acetyl CoA

Krebs Cycle

FADH2's Produced

22

Times Per

Glucose

Total ATP's Produced

ATP's per NADH or FADH2

1

31

1

x3

x3

x2x3

x1x1

x2

x2x2

x2

8

6

24

38Total ATP's per Glucose

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.

OUTERMEMBRANE

INNER`MEMBRANE

CRISTA

INTER-MEMBRANOUS SPACE MATRIX

INTRAMEMBRANOUSSPACE

MATRIX

Active Transport Electrons (and hydrogens) build up in

matrix

e-

e-

e-H+

H+

H+

H+

INTRAMEMBRANOUSSPACE

MATRIX

Active Transport As electrons are transported, H’s are

pumped into IMS.

e-

e-

e-H+

H+

H+

H+

e-

H+H+ H+

INTRAMEMBRANOUSSPACE

MATRIX

Eventually a high chemiosmotic gradient of protons develops.

e-

e-

e-H+

H+

H+

H+

e-

H+H+ H+

H+

H+H+ H+

H+

H+

H+

H+

H+

H+

H+

H+

H+

H+

H+

H+

H+

INTRAMEMBRANOUSSPACE

MATRIX

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

e-

e-

e-H+

H+

H+

H+

e-

H+H+ H+

H+

H+H+ H+

H+

H+

H+

H+

H+

H+

H+

H+

H+

H+

H+

H+

H+

ATP Synthetase

INTRAMEMBRANOUSSPACE

MATRIX

H+

H+

H+

H+H+H+

H+ H+

H+

H+

H+ H+

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

ATPADPH+