Chapter 9

Cellular Respiration

Overview of Cellular Resiration

C6H12O6 + 6O2 ------------> 6CO2 + 6H2O + ATP (energy)

! when oxygen is present, glycolysis is followed by the Krebs cycle and electron transport chain

! glycolysis, Krebs cycle, electron transport chain = cellular respiration (aerobic process)

enzymes

3 Stages of Cellular RespirationGlycolysis: 1st set of reactions; occurs in the cytoplasm; glucose is broken down to produce 2 pyruvic acid molecules and a net gain of 2 ATP.

Kreb’s Cycle (Citric Acid Cycle): pyruvic acid from glycolysis is broken down to produce carbon dioxide in a series of energy extracting reactions

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Electron Transport Chain: uses high energy electrons from the Kreb’s cycle to convert ADP into ATP; occurs in the mitochondria

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The Totals

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How efficient is the process of cellular respiration?

! 1 glucose molecule = 36 ATP molecules = 38% of the total energy in glucose

! The remaining 62% is released as heat

2 Main Types of Fermentation

Alcoholic Fermentation ! Used by yeasts ! Equation:

Pyruvic Acid + NADH ---> alcohol +CO2 + NAD+

Glycolysis is followed by fermentation when oxygen is not present (anaerobic)

Lactic Acid FermentationLactic Acid Fermentation ! Occurs in our muscle cells during rapid exercise\ ! Equation:

pyruvic acid + NADH ---> lactic acid + NAD+

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Which type of respiration is more efficient in terms of ATP

! Aerobic respiration because it produces 36 ATP molecules per every molecule of glucose

! Anaerobic Respiration (Fermentation) only produces 2 ATP molecules per every molecule of glucose

Comparing Photosynthesis & Cellular Respiration

Photosynthesis & Cell Respiration

Cycle