Cellular RespirationCellular respiration: A catabolic energy yielding pathway in which oxygen and organic fuels are consumed and ATP is produced

• An aerobic process—it requires oxygen

Organic + Oxygen Carbon + Water + EnergyCompounds

Dioxide

Summary equations:

Energy ConversionFuel rich inchemicalenergy

Energy conversionWaste productspoor in chemical

energy

Gasoline

Oxygen

Carbon dioxide

WaterEnergy conversion in a car

Energy for cellular work

Energy conversion in a cell

Heatenergy

Heatenergy

Carbon dioxide

Water

Food

Oxygen

Combustion

Cellularrespiration

Kinetic energy

of movement

ATP

Cellular Respiration

C6H12O6 CO2O2H2O

Glucose Oxygen Carbondioxide

Water

6 66

Reduction

Oxidation

Oxygen gains electrons (and hydrogens)

Glucose loses electrons(and hydrogens)

•By oxidizing glucose, energy is taken out of “storage” and made available for ATP synthesis

Metabolic Disequilibrium

*Multistep open hydroelectric system

3 metabolic stages:

*glycolysis *Krebs cycle

*electron transport chain and oxidative phosphorylation

*Substrate-level phosphorylation

*Oxidative phosphorylation

Cellular Respiration

Cytoplasm

Cytoplasm

Animal cell Plant cell

Mitochondrion

High-energyelectronscarriedby NADH

High-energyelectrons carriedmainly byNADH

CitricAcidCycle

ElectronTransport

Glycolysis

Glucose2

Pyruvicacid

ATP ATP ATP

Figure 6.6

CytoplasmCytoplasm

Cytoplasm

Animal cell Plant cell

Mitochondrion

Mitochondrion

High-energyelectronscarried

by NADH

High-energyelectrons carried

mainly byNADH

CitricAcidCycle

ElectronTransport

Glycolysis

ATP ATP ATP2 2 ~34~38 ATP

per glucose

Glycolysis harvests chemical energy by oxidizing glucose to pyruvate.

Cellular Respiration

1) Glucose is phosphorylated

2) G-6-P is rearranged

3) Addition of another phosphate group

5) Conversion b/w the 2 3-carbon sugars

4) Cleavage into 2 3-carbon sugars

Cellular Respiration

6) Two components: *electron transfer *Phosphate group addition

Glycolysis: Energy Payoff Phase

7) ATP production

8) Rearrangement of phosphate group

9) Loss of water

10) ATP production

Cellular Respiration

Fermentation

aerobicanaerobic

The Krebs cycle: energy-yielding oxidation

The junction b/w glycolysis and the Krebs cycle:

Multienzyme complex:

1) Removal of CO2 2) Electron transfer *pyruvate dehydrogenase 3) Addition of CoA

Cellular Respiration

The Krebs cycle: energy-yielding oxidation

1) Addition of 2 Carbons Citrate synthase

2) Isomerization Aconitase

3) *Loss of CO2 *electron transfer

Isocitrate dehydrogenase

4) *Loss of CO2 *electron transfer a-ketoglutarate dehydrogenase

5) substrate-level phosphorylation Succinyl CoA-synthetase

6) electron transfer Succinate

dehydrogenase

7) Rearrangement of bonds

Fumarase

8) electron transfer Malate dehydrogenase

Cellular Respiration

Electron transport and ATP synthesis

*Multi-step open system

Cellular Respiration

Generation and maintenance of an H+ gradient*Exergonic flow of e-, pumps H+ across the membrane

*chemiosmosis

high energy electrons

Cellular Respiration

*How does the mitochondrion couple electron transport and ATP synthesis?

ATP synthase

Cellular Respiration

Versatility of Cellular Respiration

Food

Polysaccharides Fats Proteins

Sugars Glycerol Fatty acids

Amino acids

Glycolysis AcetylCoA

CitricAcidCycle

ElectronTransport

ATP

– In addition to glucose, cellular respiration can “burn”:• Diverse types of carbohydrates• Fats• Proteins