1. The details behind catabolic cellular energetics
Cellular Respiration
The details behind catabolic cellular energetics

2. Oxidation-Reduction OIL RIG vs LEO says GER
Can’t have oxidation without reduction
One atom/element’s loss is another’s gain
C6H12O O2  6CO H2O + energy
OXIDIZED—loses e- to O2
REDUCED—gains e- from glucose
(protons follow to form water)

3. Oxidation-Reduction
The reduced form of the molecule has MORE potential energy than the oxidized form
The electrons that are being transferred are carrying energy with them
Looking at the half-reactions for respiration helps to see exactly what is oxidized and what is reduced

4. Oxidation-Reduction
OXIDIZED
REDUCED

5. Oxidation-Reduction OXIDATION REDUCTION Loss of electrons
Gain of electrons
Gain of oxygen
Loss of oxygen
Loss of hydrogen
Gain of hydrogen
Results in many C—O bonds
Results in many C—H bonds
Results in a compound with lower potential energy
Results in a compound with higher potential energy

6. Respiration Step 1: Glycolysis No oxygen needed
Occurs in the cytosol of the cell
3 main stages:
Phosphorylation
Lysis
Oxidation

7. Respiration--Glycolysis
Phosphorylation uses TWO (2) ATPs to add a phosphate to each end of a glucose molecule
2 ATP
2 ADP P

8. ATP - Adenosine TriPhosphate

9. ATP is “spring-loaded”
The phosphates have a negative charge –repel each other
This means potential energy is stored in the bonds

10. What happens to the ATP when the spring is released?
A phosphate is removed
Energy is released
It becomes ADP (adenosine Diphosphate)

11. Respiration--Glycolysis
Lysis occurs when the phosphorylated 6-carbon compound splits into TWO 3-carbon molecules P P

12. Respiration--Glycolysis
Each 3-carbon enters an Oxidation phase where ATP & NADH are formed, leaving two pyruvates 2
2 pyruvate P Pi
2 NAD+
2 NADH P
4 ADP
4ATP

13. Respiration--Glycolysis
SUMMARY:
2 ATPs needed, 4 produced, NET GAIN 2 ATP
2 NADH formed
2 Pyruvate formed
Lysis
SUBSTRATE level phosphorylation
Oxidation
ATP Formation
Occurs in cytoplasm
Controlled by enzymes
*High ATP levels  feedback inhibition stops glycolysis P
2 NAD+
2 NADH Pi
4 ADP
4ATP

14. Electron carriers
NAD > NADH
FADH > FADH2

15. Respiration after glycolysis
O2 + mitochondrion = continued respiration
Before you can get to the mitochondria, a link reaction must take place

16. Respiration after glycolysis
Substrate most often discussed during respiration is glucose
But! Acetyl CoA can be produced using most carbohydrates and lipids/fats
If ATP levels are high, acetyl CoA synthesized into lipids for energy storage
If ATP levels are low acetyl CoA enters Kreb’s cycle in the matrix of mitochondria

17. Respiration after glycolysis
DO NOT need to know all of the names of the intermediates in the Kreb’s cycle, just the overall process

18. Respiration—Kreb’s Cycle
Kreb’s cycle happens 2x for EACH glucose
SUMMARY
2 ATPS (from GTP)
6 NADH*
2 FADH2*
4 CO2 released
* Transfers e- to ETC

19. Respiration—ATP scoreboard
PROCESS
ATP
GLYCOLYSIS
4 PRODUCED
2 per pyruvate (2 pyruvates) substrate level phosphorylation*
GLYCOYSIS
2 CONSUMED
KREB’S CYCLE
2 PRODUCED
1 per cycle (2 rotations per glucose)
TOTAL through Kreb’s +4
*Understand difference between this and oxidative phosphorylation

20. Respiration—Electron Transport Chain
Main energy producer of respiration
Oxygen needed for the first time
Occurs inside the mitochondrial inner membrane
Embedded within the membrane of the cristae are molecules that are easily oxidized and reduced
Called carrier molecules b/c the carry electrons/energy
Physically close to each other, pass e- from one to the next, based on differences in electronegativity

21. Respiration—Electron Transport Chain
Electrons come from NADH and FADH2 generated in earlier steps
1 NADH 3 ATPs
2 FADH2  2 ATPs
End result, OXYGEN final electron acceptor, gets reduced, water is produced
ATP produced in large scale by oxidative phosphorylation

22. Respiration—Electron Transport Chain
Oxidative phosphorylation occurs as a result of an energy gradient
Gradient established as H+ ions (protons) get pushed into the intermembrane space of the mitochondria
This process is called CHEMIOSMOSIS
As H+ ions come back into matrix via ATP Synthase energy used to reduce oxygen and covert ADP to ATP (oxidative phosphorylation)

23. Goal – making ATP!
Substrate level phosphorylation – enzyme transfers a P to ADP from a substrate (glucose parts)
Oxidative phosphorylation – powered by redox reactions in ETC (ATP synthase turns)

24. Respiration—Oxidative Phosphorylation

25. Respiration—ATP scoreboard
Glucose  NADH or FADH2  ETC  chemiosmosis  ATP*
PROCESS
ATP
GLYCOLYSIS
4 PRODUCED
2 per pyruvate (2 pyruvates)
GLYCOYSIS
2 CONSUMED
KREB’S CYCLE
2 PRODUCED
1 per cycle (2 rotations per glucose)
Transport of NADH into Mitochondria
Electron Transport Chain 34
(10 NADH x 3, 2 FADH2 x 2)
TOTAL during catabolism of 1 glucose molecule
+36
*Only 30% of all energy stored in glucose bonds, rest given off as heat