1. Cellular Respiration
Unit III
Chapter 9

2. Flash Cards Due Tomorrow
Respiration
Next 3 should have (what they do, where they occur, and what they produce)
Glycolysis
Krebs Cycle
Electron Transport
Pyruvate
Aerobic Respiration
Anaerobic Respiration
Fermentation

3. Overview of Cellular Respiration
Cellular respiration is the process that releases energy by breaking down food molecules in the presence of oxygen
Organisms that respire: animals, fungi, plants (during night hours)
Cellular respiration requires a food molecule (such as glucose), oxygen, and it gives off carbon dioxide
Because is occurs in the PRESENCE of OXYGEN, cellular respiration is known as AEROBIC respiration

4. Chemical Formula for Cellular Respiration
The chemical formula for cellular respiration is:
6O2 + C6H12O6 → 6 CO H2O + Energy
oxygen + glucose → carbon dioxide + water + energy
The reactants of cellular respiration are:
oxygen (O2) & glucose (C6H12O6)
The products of cellular respiration are:
carbon dioxide (CO2) and water (H2O)

5. The 3 main stages of cellular respiration are:
Glycolysis
Krebs Cycle (Citric Acid Cycle)
Electron Transport

6. Visual Overview of Cellular Respiration
Krebs
Cycle

7. Glycolysis
The first set of reactions in cellular respiration is glycolysis
Glycolysis is the process in which 1 molecule of glucose is broken in half, producing 2 molecules of pyruvic acid
Glycolysis occurs in the cytoplasm of the cell
Glycolysis produces a total of 4 ATP, but requires 2 ATP in the beginning to get through the membrane of the mitochondria
Therefore, the NET ATP YIELD of glycolysis is 2 ATP

8. The Krebs Cycle
In the presence of oxygen, the pyruvic acid produced during glycolysis passes to the Krebs cycle
During the Krebs cycle, pyruvic acid is broken down into carbon dioxide in a series of energy-extracting reactions
Every time you exhale, you expel the CO2 produced by the Krebs cycle

9. Electron Transport
Following the Krebs cycle, the electrons captured by NADH are passed to the electron transport chain
The electron transport chain uses the high-energy electrons from the Krebs cycle to convert ADP to ATP
Every time 2 high energy electrons transport down the ETC, their energy is used to transport H+ across the inner membrane of the mitochondria…this creates a + charge on the inside of the membrane and a – charge in the matrix of the mitochondria
As a result of this charge difference, H+ ions escape through channel proteins called ATP synthase causing it to rotate
Each time it rotates, the enzyme ATP synthase grabs a low energy ADP and attaches a phosphate, forming high-energy ATP

10. Electron Transport Chain
inner membrane
space
inner membrane
Matrix
of mitochondria

11. The Energy Totals
The complete breakdown of 1 glucose molecule through cellular respiration results in the production of 36 molecules of ATP
Net Energy Gain:
38 ATP Produced
- 2 ATP needed to start
36 ATP made!

12. Respiration in the Absence of Oxygen
When oxygen is NOT present, glycolysis is followed by a different pathway called fermentation
Because fermentation does not require oxygen, it is said to be anaerobic

13. Two Main Types of Fermentation
Lactic Acid Fermentation: glucose  lactic acid (Ex: Muscles)
Alcohol Fermentation: glucose  ethanol (Ex: Yeast, baking, alcohol production)
BOTH types of ANAEROBIC RESPIRATION = net gain of 2 ATP