1. CELLULAR RESPIRATION

2. I. General Info
Definition: Cellular respiration is the break down of food to get energy (ATP)
Enzymes control every step of this process
All living things respire
Overall chemical equation:
C6H12O6 + 6O2 —> 6CO2 + 6H2O + 36 ATP

3. From Food to ATP

4. Functions of ATP
Chemical work –supplies energy needed to make macromolecules
Transport work –supplies energy to transport substances across the cell membrane.
Mechanical work –supplies energy to allow muscle contraction, separation of chromosomes etc.

5. Respiration Pathways
Food is broken down and energy is released in a three stage process
Glycolysis
Kreb’s Cycle
Electron Transport
Draw Fig. 9-2, pg. 222

6. Electron Transport Chain
Cellular Respiration
Glucose (C6H1206) +
Oxygen (02)
Glycolysis
Krebs Cycle
Electron Transport Chain
Carbon
Dioxide
(CO2) +
Water
(H2O)

7. To the electron transport chain
Glycolysis
Takes place in the cytoplasm of a cell.
Does not require oxygen.
Two ATP molecules are formed.
Summary: Glucose (has 6 carbons) is broken down into 2 pyruvic acid molecules (each has 3 carbons)
Chemical overview
Glycolysis means “splitting of sugar”
Glucose
2 Pyruvic acid
2 Pyruvic acid
DRAW FIG 9-3, pg. 223
To the electron transport chain

9. Anaerobic Pathways O2 What does anaerobic mean?
When oxygen is not present, glycolosis is followed by fermentation (2 types)
Alcohol Fermentation
In yeast O2
CH3—C—COO O
+ NADH
CH3—CH2OH +
CO2 + NAD+
Ethanol
Pyruvic Acid
ATP is produced and NADH is converted to NAD+ allowing glycolysis to continue

10. O2 Lactic Acid Fermentation (feel the burn!)
Lactic acid is produced in muscles of birds and mammals when the body can’t supply enough O2 to tissues
Regenerates NAD+ so glycolysis can continue
Glycolysis
Lactic Acid Fermentation O2
Pyruvic acid
Glucose
Lactic acid
DRAW FIG. 9-4, pg. 225
Prokaryotic organisms produce lactic acid that is used in the production of foods like yogurt, cheese, buttermilk, sour cream, kimchi, pickles and sauerkrat.
Oxygen debt: the amount of O2 required to convert lactic acid back to pyruvic acid.

12. Mitochondria Double membrane organelle Central cavity known as matrix
Inner membrane folds known as cristae
Draw Fig. 9-1, pg 221

14. Krebs Cycle (Citric Acid Cycle)
Requires oxygen.
Takes place in the mitochondrial matrix.
2 ATP molecules are generated.
Pyruvic acid (made during glycolysis) is broken down into CO2 in a series of energy-extracting reactions.
High-energy electrons are generated and accepted by electron carriers (NAD+ and FAD)
Requires an intermediate step before the cycle can begin…

15. G. Intermediate Step
One C atom from a pyruvic acid molecule becomes part of CO2
The other two C atoms combine with CoEnzyme A to form Acetyl-CoEnzymeA
Then Acetyl-CoEnzyme A enters the Kreb cycle by combining with a 4-carbon compound to form a 6-carbon compound (citric acid)
you are “burning” carbon and releasing it as carbon dioxide every time you breathe out

16. What happens to the high energy electrons carried on FADH2 and NADH?
Draw Kreb’s Cycle
Pg. 227
Why is it called a cycle?
What happens to the high energy electrons carried on FADH2 and NADH?

19. Electron Transport Chain
High energy electrons from the Kreb’s cycle are transported by NADH and FADH2 to the Electron Transport Chain.
On the cristae of the mitochondria, electrons are transferred from one carrier protein to another creating energy.
This process produces 32 ATP.
At the end of the chain an enzyme combines these “used up” electrons with H+ ions and oxygen to form water.
As high energy electrons “fall” they lose energy to create ATP. Oxygen has high electron affinity and pull the electrons down to the end of the chain forming water. It is essential as the final electron acceptor combining with H ions and making water

20. Electron Transport Chain (Fig 9-7, pg. 228)
Hydrogen Ion Movement
Channel
Intermembrane
Space
ATP synthase
Inner
Membrane
Matrix
ATP Production

23. Fermentation (without oxygen)
The Big Picture 2 2 32
Glucose
36 ATP
Krebs cycle
Electron transport
Glycolysis
Draw Fig 9-8; pg 229
Alcohol or lactic acid
Fermentation (without oxygen)
Cellular Respiration
C6H12O6
+ 6 O2
6 H2O
+ 6 CO2
Photosynthesis