Cellular Respiration

How organisms make ATP

Cellular Respiration • The process that produces energy

(ATP) by breaking down food molecules

6O2 + C6H12O6 6CO2 + 6H2O

Glycolysis: the first step in respiration

• Happens in the cytoplasm• Glucose is split into 2 molecules of

pyruvic acid• Results in the net production of 2

ATP

Two Types of RespirationAerobic

• Occurs in the presence of oxygen

• Occurs in the mitochondria

• Krebs cycle – pyruvic acid is broken down into carbon dioxide in a series of energy producing steps (electron transport chain)

• Net ATP production: 34 ATP (per glucose molecule) + 2 ATP (glycolysis) = 36 ATP

Anaerobic• Fermentation – occurs

in the absence of oxygen. Two types:• alcohol fermentation • lactic acid fermentation

• Occurs in the cytoplasm

• Net ATP production: 2 ATP per glucose molecule

Two Pathways to ATPAerobic

1. Glycolysis = 2 ATP2. O2 present =3. Pyruvic acid

enters the mitochondria

4. 34 ATP produced5. Net ATP = 36

Anaerobic1. Glycolysis = 2 ATP2. No O2 present = 3. Lactic acid or

alcohol fermentation

4. No additional ATP produced

5. Net ATP = 2

Mitochondria Drawing• Copy, color, and glue in the

MITOCHONDRIA, figure 4.2 on page 108.

• I’ll check off next class for 10 points.