Cellular Respiration

pp. 77 to 82

What is it?• A process to convert glucose to ATP in

order to obtain energy

• Occurs in all organisms (plants and animals)– Plants continue their quest to get food

(glucose is made in photosynthesis. Cellular respiration continues the process)

Glucose + Oxygen = Carbon Dioxide + Water + Chemical Energy C6H12O6 6O2 6CO2 6H2O 36 ATP

Types of Cellular Respiration

1. Aerobic cellular respiration• Uses oxygen in process• Makes large # of ATP molecules• Primary process for humans

2. Anaerobic cellular respiration• No oxygen is used• Makes small # of ATP molecules

Aerobic Respiration

1. Glycolysis (in cytoplasm)• A molecule of glucose (C6H12O6) is broken two

into 2 molecules of pyruvate (C3H6O3). Energy is released (2 ATP)

• Oxidative Respiration (in mitochondria)• The 2 pyruvates react with 6 molecules of O2

(that is inhaled) to make 6 molecules of CO2 and 6 molecules of water. Energy is released (34 ATP).

Oxidative respiration

36 ATP total!

Anaerobic Respiration

• No oxygen, but ATP still can be made from glucose in a special way! Occurs in cytoplasm of cell.

1. Ethanol Fermentation (bread, liquor, soy sauce, etc)

2. Lactic Acid Fermentation (heavy exercise)

1. Glycolysis - Glucose broken down into 2 pyruvate. Energy is released (2 ATP).

2. Enzyme converts the 2 pyruvates to CO2 and ethanol.

• Baking bread yeast eats the glucose in flour and expels CO2 and ethanol (sweet smell). Ethanol evaporates when baked.

• Alcohol yeast eats glucose in sugary grape juice and expels CO2 and ethanol.

Ethanol Fermentation

Lactic Acid Fermentation

• When working out, humans convert glucose into ATP to get energy to sustain workout.

• Glucose broken down into 2 pyruvates. Energy is released (2 ATP).

• Eventually, oxygen cannot keep up with demands of glucose conversion (there is just not enough oxygen for this amount of energy needed)

• Enzyme in muscle cells convert the 2 pyruvates into lactic acid

• The more lactic acid, the more sore/stiff your muscles are.

Aerobic vs. Anaerobic

• With oxygen• Occurs in

mitochondria of cell• 36 ATP molecules

made • More efficient• Plants, animals use

this

• No oxygen• Occurs in cytoplasm

of cell• 2 ATP molecules

made• Less efficient• Simple organisms

(yeast, bacteria, etc) use this; humans doing heavy exercise