1. Cellular Respiration
C6H12O6 + 6 O2 6 CO2 + 6H2O + 38 ATP

2. Cellular Respiration: An Overview
Process by which cells convert the energy in food (usually glucose) into usable ATP.
Terms to Know…
Oxidation = the loss of electrons
Compound becomes more positive
Reduction = the gain of electrons
Compound becomes more negative
Electrons and protons (H+) travel TOGETHER
NAD+ = coenzyme derived from niacin; acts as a H+ and e- acceptor. AN ENERGY CARRIER!

3. Cellular Respiration: An Overview

4. Substrate-Level Phosphorylation
An enzyme transfers a phosphate group directly from an organic molecule to ADP to form ATP
The ATP produced in Glycolysis & the Krebs Cycle is produced by this method.

5. Oxidative Phosphorylation (ETC + Chemiosmosis)
The production of ATP by using energy derived from the redox reactions of the Electron Transport Chain.
The enzyme ATP synthase is needed to phosphorylate the ADP to produce ATP.
Almost 90% of the ATP produced from cellular respiration is produced this way.

6. Anaerobic Respiration
Cellular Respiration
Glucose
Glycolysis
ATP
Oxygen Absent
Oxygen Present
Anaerobic Respiration
(Fermentation)
Aerobic Respiration
(Krebs Cycle & ETC)
ATP

7. Glycolysis “glucose-splitting” Big Picture: Occurs in the cytosol
Glucose (6-C) is broken down into 2 molecules of pyruvate (3-C)
Occurs in the cytosol
Occurs with or without oxygen
Made up of 2 phases:
Energy investment phase
Energy yielding phase

8. Glycolysis: Energy Investment Phase
Glucose is converted into 2 G3P (Glyceraldehyde-3-phosphate)
Requires 2 ATP

9. Glycolysis: Energy-Yielding Phase
2 G3P are converted into 2 Pyruvate (3C) molecules.
Dehydrogenase enzymes remove H from intermediate compounds and attach them to 2 NAD to produce 2NADH

10. Net Gain in Glycolysis 2 ATP 2 NADH - 2 ATP (Energy investment phase)
+ 4 ATP (Energy yielding phase)
+ 2 ATP
2 NADH
Electron carriers
Will be used to make ATP later 

11. Choices, Choices!  If oxygen is absent, anaerobic respiration occurs
Fermentation
Yeast & some bacteria  alcoholic fermentation
Animal muscle lactic acid fermentation
If oxygen is present, aerobic respiration occurs
Krebs Cycle and Electron Transport Chain

12. Anaerobic Respiration
Cellular Respiration
Glucose
Glycolysis
ATP
Oxygen Absent
Oxygen Present
Anaerobic Respiration
(Fermentation)
Aerobic Respiration
ATP

13. Fermentation 2 major types:
Alcoholic and lactic acid fermentation
NAD+ acts as a hydrogen acceptor during glycolysis
If the supply of NAD+ runs out, then glycolysis would have to stop.
Fermentation occurs as simply a means of recycling the NAD+, so that glycolysis can occur again.

14. Alcoholic Fermentation
Occurs in some BACTERIA and YEAST
2 step process:
Carbon dioxide is released from pyruvate (3-C), forming acetaldehyde (2-C)
Acetaldehyde is reduced by NADH (gains an electron), forming ethyl alcohol (ethanol)
NAD+ is regenerated, thereby allowing glycolysis to continue
Used to produce beer and wine

15. Lactic Acid Fermentation
Occurs in ANIMALS
1 step process:
Pyruvate is reduced by NADH (gains an electron), forming lactic acid
NAD+ is regenerated, thereby allowing glycolysis to continue
Occurs in muscle cells, causing muscle pain and fatigue

16. Anaerobic Respiration
Cellular Respiration
Glucose
Glycolysis
ATP
Oxygen Absent
Oxygen Present
Anaerobic Respiration
(Fermentation)
Aerobic Respiration
ATP

17. Aerobic Respiration
After glycolysis, most of the energy from glucose remains “locked” in 2 molecules of pyruvate
If oxygen is present, the pyruvate enters the mitochondrial matrix to complete the Krebs Cycle
Pyruvate (3-C) is converted to Acetyl CoA (2-C)
CO2 is released as a waste product
NADH is produced

19. The Krebs Cycle Yield per pyruvate molecule:
4 NADH
1 FADH2
1 ATP
2 CO2
Yield per glucose molecule (two turns of Krebs Cycle):
8 NADH
2 FADH2
2 ATP
6 CO2
CO2 released as a waste product

20. Electron Transport Chain
The ETC converts the NADH and FADH2 from glycolysis and the Krebs Cycle into ATP
Occurs in inner membrane of mitochondrion
The energy in each NADH molecule moves enough protons (H+) into the mitochondrial matrix to create 3 ATP
1 FADH2  2 ATP

21. The Electron Transport Chain
The electrons from NADH and FADH2 are passed from one electron acceptor molecule to another.
Each electron acceptor is more electronegative than the last.
Oxygen is the final electron acceptor e-
ETC
oxygen

22. Chemiosmosis
Similarly to photosynthesis, the energy the electrons lose along the way moves H+ out of the matrix and into the intermembrane space of the mitochondrion
As H+ ions diffuse through the membrane, ATP synthase uses the energy to join ADP and a phosphate group  ATP

23. Oxidative Phosphorylation: ETC & Chemiosmosis

24. Aerobic Respiration: Total Energy Yield
Glycolysis:
2 ATP (Net)
2 NADH  6 ATP
Krebs Cycle:
2 ATP
8 NADH  24 ATP (ETC)
2 FADH2  4 ATP (ETC)
TOTAL:
8 ATP + 30 ATP  38 ATP