1. CH 2. CELLULAR RESPIRATION
How are these two images related?

2. CH 2. CELLULAR RESPIRATION
Cellular respiration is the process whereby the body converts the energy that we get from food (glucose) into an energy form that the body can use – ATP!
FOOD =
GLUCOSE
ATP!!!!!!

3. CH 2. CELLULAR RESPIRATION
There are 2 major types of cellular respiration…
1. AEROBIC CELLULAR RESPIRATION
2. ANAEROBIC CELLULAR RESPIRATION
The big difference is oxygen!!!!!

4. CH 2. CELLULAR RESPIRATION
There are 2 major types of cellular respiration…
AEROBIC CELLULAR RESPIRATION
Uses oxygen and produces MORE energy!
ANAEROBIC CELLULAR RESPIRATION
Does NOT use oxygen, produces LESS energy but much faster!

5. CH 2. CELLULAR RESPIRATION
AEROBIC CELLULAR RESPIRATION – includes anaerobic cellular respiration plus 3 extra steps.
Overall, there are 4 stages to cellular respiration:
1. GLYCOLYSIS – a 10 step process occurring in the cytoplasm
2. PYRUVATE OXIDATION – a one-step process in the mitochondrial matrix
3. THE KREBS CYCLE – an 8 step cyclical process occurring in the mitochondrial matrix
4. ELECTRON TRANSPORT CHAIN – a multistep process occurring in the mitochondrial membrane

6. CH 2. CELLULAR RESPIRATION
The overall chemical equation for cellular respiration is as follows:
C6H12O6(aq) + 6O2(g)   6CO2(g) + 6H2O(l) + 36 ATP
Carbon dioxide
water
glucose
oxygen
ENERGY!
In other words, the combustion of one molecule of glucose yields 36 molecules of ATP along with carbon dioxide and water as by-products.
Since the activation energy needed for the combustion of glucose is quite high, each step in cellular respiration is catalyzed by specific enzymes that lower the activation energies and allow the reactions to occur at a pace fast enough to maintain cell needs.

7. CH 2. CELLULAR RESPIRATION
The 3 overall goals of this process are:
1. to break the bonds between the six carbon atoms of glucose, resulting in 6 carbon dioxide molecules.
2. to move hydrogen atom electrons from glucose to oxygen, forming 6 water molecules.
3. to trap as much of the free energy released in the process as possible in the form of ATP.
C6H12O6(aq) + 6O2(g)   6CO2(g) + 6H2O(l) + 36 ATP

8. Two 3-C molecules of pyruvate
STEP ONE: GLYCOLYSIS
Glycolysis involves 10 enzyme-catalyzed reactions (each step has its own specialized enzyme!)
Each reaction of glycolysis occurs in the cell's cytoplasm
2NADH
2ATP
C6H12O6(aq)
Two 3-C molecules of pyruvate

9. (-2ATP) + 4ATP = 2ATP (net yield)
STEP ONE: GLYCOLYSIS
In glycolysis, a total of 2 ATP molecules are USED in step one and three
2 ATP are produced in the 7th step, when BPG phosphorylates ADP to ATP
2 ATP are produced in the 10th step when PEP phosphorylates ADP to ATP
(-2ATP) + 4ATP = 2ATP (net yield)

10. STEP ONE: GLYCOLYSIS

11. STEP TWO: PYRUVATE OXIDATION
TIME TO MOVE INTO THE MITOCHONDRIA!!!!
the 2 molecules of pyruvate from glycolysis are transported through the two mitochondrial membranes into the matrix
In the matrix, a multi-enzyme complex catalyzes 3 MAJOR CHANGES!!!!

12. STEP TWO: PYRUVATE OXIDATION
1. A low-energy carboxyl group is removed as CO2.

13. STEP TWO: PYRUVATE OXIDATION
2. NAD+ is reduced by two H atoms

14. STEP TWO: PYRUVATE OXIDATION
3. A sulfur-containing compound called coenzyme A (CoA) is attached to the remaining acetic acid portion – forming a molecule called acetyl-CoA

15. STEP TWO: PYRUVATE OXIDATION
The following is the overall equation for pyruvate oxidation:
2 pyruvate + 2NAD+ + 2CoA   2acetyl-CoA + 2NADH + 2H+ + 2CO2
Acetyl-CoA moves on the third step! = Krebs Cycle!
NADH skips step three and moves on to stage four! = electron transport chain!

16. Acetyl-CoA is a CENTRAL MOLECULE IN ENERGY MOTABOLISM!!!!!
WARNING!!!!!!
Acetyl-CoA is a CENTRAL MOLECULE IN ENERGY MOTABOLISM!!!!!
ALL molecules that are catabolized for energy are converted into acetyl-CoA – including proteins, lipids and carbohydrates!
acetyl-CoA is MULTIFUNCTIONAL – it can be used to produce fat or ATP
if the body needs energy, acetyl-CoA will enter the KREBS CYCLE and transfer its free energy into ATP
if the body does not need energy, acetyl-CoA is channelled into an anabolic pathway that synthesizes lipids.

17. STEP THREE: KREBS CYCLE
The Krebs Cycle is an 8-step process!!!!
each step is catalyzed by its own enzyme
It is a cyclic process!
the product of step 8 (oxaloacetate) is the reactant in step 1!!!!!
The Krebs Cycle is a cyclic series of reactions that transfers energy from organic molecules to ATP, NADH, and FADH2 and removes carbon atoms as CO2.

18. STEP THREE: KREBS CYCLE

19. STEP THREE: KREBS CYCLE
By the end of the Krebs cycle, the original glucose molecule is entirely consumed!
the 6 carbon atoms leave as low energy CO2 molecules
The Krebs Cycle produces:
2 molecules of CO2
3 NADH
1 ATP
1 FADH2
X 2
Because there are 2 acetyl-CoA molecules that go through

20. The reduced coenzymes now go on to stage 4  ELECTRON TRANSPORT CHAIN
The Krebs Cycle produces:
4 molecules of CO2
6 NADH
2 ATP
2 FADH2
Energy is harvested in steps 3,4,5,6 & 8 :
In steps 3, 4 and 8  NAD+ is reduced to NADH
In step 5  ATP is formed by phosphorylation
In step 6  FAD is reduced to FADH2
The reduced coenzymes now go on to stage 4  ELECTRON TRANSPORT CHAIN

21. STEP FOUR: ELECTRON TRANSPORT CHAIN

22. STEP FOUR: ELECTRON TRANSPORT CHAIN
each NADH molecule results in 3 ATP molecules
each FADH2 molecule results in 2 ATP molecules

23. ENERGY TOTALS!!!
review pg. 110 – figure 25
Review pg. 114 – table 3