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Cellular Respiration

Aerobic and Anaerobic Metabolism

Glycolysis takes place in the cytoplasm

Glycolysis Simplified (greatly ☺☺☺☺)

If oxygen is available (aerobic), then pyruvate enters the Krebs cycle

If oxygen is not available(anaerobic), then pyruvate undergoes fermentation

Aerobic respiration

Synonymous Terms

• Krebs cycle

• Citric acid cycle

• Tri-carboxylic acid cycle (TCA cycle)

Mitochondrial Structure

The Krebs cycle takes place across inner membrane space (matrix) of the mitochondrion

ElectronTransport

The Role of Oxygen (O2)

Oxygen is the terminal (final) electron acceptor

½ O2 + 2H+ + 2e- ���� H2O

∴ Oxygen is needed only in the very LAST step of cellular respiration!

Mitochondrial Structure

Infoldings (cristae) increase the area of membrane surface available for electron transport

Aerobic Respiration

C6H12O6 + 6O2 → 6CO2 + 6H2O + 38 ATP

� The Krebs cycle and electron transporttake place in the mitochondria� The Krebs cycle and electron transport maximize ATP yield

� 38 ATP vs. 2 ATP for fermentation

Anaerobic Respiration(Alcohol Fermentation)

C6H12O6 → 2 CH3CH2OH + 2 CO2 + 2 ATP

glucose ethyl alcohol carbon

dioxide

Alcohol fermentation takes place in yeastand some bacteria, and yields only the2 ATP produced in glycolysis

Anaerobic Respiration(Lactic Acid Fermentation)C6H12O6 → 2 C3H6O3 + 2 ATP

glucose lactic acid

Lactic acid fermentation takes place inanimal cells and some bacteria and fungi;it yields only the 2 ATP produced in glycolysis.