1. CELLULAR RESPIRATION

2. glucose + oxygen → carbon dioxide + water +ATP
Cellular Respiration
Cellular Respiration: Process by which mitochondria break down food molecules to produce ATP in plants and animals
glucose + oxygen → carbon dioxide + water +ATP or
C6H12O6 + 6O2→ 6CO2 + 6H2O +ATP
Changes organic chemical energy (glucose) into inorganic chemical energy (ATP)
There are three stages of Cellular Respiration
Glycolysis
Anaerobic – does not require oxygen
Citric Acid (Krebs) Cycle
Aerobic – does require oxygen
Electron Transport Chain

3. Glycolysis
Glycolysis: Breaks down glucose into two molecules of pyruvate (a colorless acid formed as an intermediate in metabolism)
This reaction uses enzymes and takes place in the *cytoplasm* of the cell (anaerobic reaction)
Produces:
2 pyruvate molecules (used in the next step of Cellular Respiration)
2 ATP molecules (energy the cell can use)
2 NADH (electron carrier similar to NADPH)

4. Into the Mitochondria…
Before the next step of Cellular Respiration can occur, the pyruvic acid molecules must go into the *mitochondria*
Two oxygen-dependent (aerobic) reactions: Citric Acid Cycle (or Krebs Cycle) and the Electron Transport Chain
Pyruvate → carbon dioxide + water + ATP
AEROBIC PART BEGINS!

5. Citric Acid/Krebs Cycle (see page 119 in your book)
CO2 is released
Pyruvate from Glycolysis fuels the cycle 4
CO2 is released
NADH and FADH2 is released
ATP is released

6. Citric Acid/Krebs Cycle
Every turn yields 1 ATP, 4 NADH, and 1 FADH2 (on average); 3 CO2 (waste product)
But it turns two times for every glucose molecule!
So 2 ATP, 8 NADH, and 2 FADH2 ; 6 CO2 (waste)

7. Electron Transport Chain
Electron Transport Chain uses the electron carriers (NADH and FADH2) to pass electrons down the protein chain and slowly release energy that is used to form ATP and water molecules
Electron Transport Chain transfers the most energy of all the steps (32-34 ATP)

8. Cellular Respiration Equation
C6H12O6 + 6O CO2 + 6H2O + energy
Carbon Dioxide – waste product of the Krebs/Citric Acid Cycle
Water – released from Electron Transport Chain
Glucose made in photosynthesis by plants or consumed by animals
Used in Glycolysis
ATP released from Glycolysis, Citric Acid Cycle, and Electron Transport Chain
Oxygen from the atmosphereUsed in Electron Transport Chain
Between ATP can be made with this process. This ATP can be used by the cells for cellular metabolism.

9. Citric Acid Cycle/Krebs Cycle Electron Transport Chain
Cellular Respiration
ATP=2
Glycolysis
Glucose
2 Pyruvic Acid
CO2
Citric Acid Cycle/Krebs Cycle
Pyruvic Acid
ATP=2
NADH and FADH2
Water
NADH and FADH
Electron Transport Chain
Oxygen
ATP=32
Total ATP=36!!!

10. Fermentation
When oxygen is not available anaerobic respiration, fermentation, can follow glycolysis INSTEAD in order to continue to produce energy.
This is not as efficient as aerobic respiration and produces far fewer ATP’s
Two types of fermentation:
Lactic acid Fermentation
Alcoholic Fermentation

11. Lactic acid Fermentation
Lactic acid fermentation occurs in muscle cells during strenuous exercise when a lot of energy is required and oxygen is scarce (oxygen debt).
Glucose → pyruvic acid → lactic acid + ATP
The lactic acid is transferred from the muscle cells to the liver where it will be converted back into pyruvic acid
The build up of lactic acid in the muscles is what causes them to be fatigued and sore.

12. Lactic Acid Fermentation
In food…
Often done by bacterial cells
Yogurt
Sauerkraut
Kimchi – Korean dish; fermented vegetables

13. Alcoholic Fermentation
Yeast and some bacteria cells are capable of alcoholic fermentation during which glucose is broken down to release CO2 and ethyl alcohol
Glucose → pyruvic acid → alcohol + CO2 + ATP
The bubbles formed by the CO2 make bread rise
The alcohol released turns grape juice into wine