1. Section 8.3 Cellular Respiration

2. Alcoholic Fermentation
Concept Map
Cellular Respiration
3 Stages
Glycolysis
Citric Acid Cycle
Electron Transport Chain
(Krebs Cycle)
Anaerobic
Pyruvic Acid
Fermentation
Alcoholic Fermentation
Lactic Acid Fermentation

3. Getting Energy to Make ATP
C6H12O6 + 6 O2  6CO2 + 6 H2O + ATP
The mitochondria in cells breaks down glucose and produces energy-in this case ATP.
EXERGONIC: Releases energy
CATABOLIC: Breaking down
molecules

4. Cellular Respiration Three stages of cellular respiration
Glycolysis - anaerobic
The Citric Acid Cycle (Kreb’s Cycle) - aerobic
The electron transport chain – aerobic
The aerobic phase produces the most ATP

5. Overview of Cellular Respiration

6. Glycolysis Takes place in the cytoplasm of the cell
It requires no oxygen (anaerobic).
Glucose (a 6 carbon molecule) is broken down into 2 molecules of pyruvate (a 3 carbon compound).
It requires 2 ATP
It produces 4 ATP
A net gain of 2 ATP

7. Glycolysis

9. The Krebs Cycle
Takes place in the mitochondria of the cell (in the matrix).
The pyruvate from glycolysis is slightly modified before the citric acid cycle begins.
These new molecules are broken down to form ATP and CO2.
One ATP per cycle is produced, two cycles occur per glucose molecule – therefore 2 ATP’s are produced by Krebs Cycle.
*Also generates high energy electrons carried by NADH and FADH2.

10. Kreb’s Cycle/Citric Acid Cycle

12. The Electron Transport Chain (makes up to 34 ATP)
The final stage of respiration
Takes place on inner mitochrondrial membrane (cristae)
Similar to the events in the light-dependent reactions of photosynthesis.
Electrons are passed from protein to protein, and the energy they give off is used to produce more ATP’s.
   The final electron acceptor is an oxygen atom.
This is why we cannot live without oxygen!
Collects H+ ions and low energy electrons! (waste)
CREATES H2O (water)

13. Electron Transport Chain

14. Where do the electrons come from?
Electrons for the ETC come from electron carriers: FADH2 and NADH
Work like NADPH (from photosynthesis)
Formation of FADH2 and NADH occurs during glycolysis and citric acid cycle
Glycolysis
NAD+ and H+ combine with e- to make NADH
Citric Acid Cycle
More NADH forms
FAD+ and H+ combine with e- to make FADH2

16. Respiration
One glucose molecule is capable of producing a net amount of ATP during the entire process of cellular respiration.
2 in glycolysis
2 from the Krebs Cycle
32 to 34 from the electron transport chain

17. Fermentation
When oxygen isn’t available, the aerobic stages of respiration obviously can’t begin.
In this situation, fermentation begins after glycolysis as an alternate form of respiration.
Why can glycolysis still go on?
Fermentation provides small amounts of ATP until the cell can once again obtain enough oxygen to begin the aerobic stages of respiration. **does not last long**

18. Fermentation Two main types – Alcoholic Fermentation
Common in yeast cells. CO2 and alcohol is produced.
Example: bread
Lactic Acid Fermentation
Occurs in animal muscle cells. Lactic acid is produced.
Example: pain in muscles from exercise

19. Yeast in Bread Yeast is a fungus It consumes the Sugar in the dough
-Dough is left to “rise”
-Yeast produces alcohol and CO2 during fermentation
-Alcohol evaporates as bread cooks
-CO2 makes bubbles – holes in bread

20. ATP and Exercise Running Sprinting uses energy: Long Term Energy
Stored in muscles: runs out quickly; within seconds
Made by lactic acid fermentation: (oxygen depleted)
made quickly, runs out quickly (about 90 seconds); lactic acid produced = burning sensation in legs
Explains why a sprinter breathes very heavily at the end of a race
Long Term Energy
Made by cellular respiration: needs oxygen which is why runners breathe heavily
Makes energy slower than fermentation; runners pace themselves
Glycogen stores last for about minutes of activity
After that, body breaks down fats and other stored molecules for energy
Aerobic Exercises = help with weight control