1. Cellular Respiration

2. Cell Metabolism
Anabolic Reaction: Using energy to construct sugar molecules
Photosynthesis
Catabolic Reactions: Breaking down sugars to release energy
Cellular Respiration

4. Photosynthesis & Cell Respiration
Reverse energy flow in these two reactions
Cell Respiration equation is the reverse of Photosynthesis equation
Photosynthesis releases O2, Cell Respiration uses O2
Photosynthesis uses CO2, Cell Respiration releases CO2
Photosynthesis: Chloroplast
Cellular Respiration: Mitochondria

6. Mitochondria & Respiration
Mitochondria have both an inner membrane & outer membrane
Cristae: folds of inner membrane
Matrix: Fluid space of mitochondria
Mitochondria & Respiration

7. Mitochondria vs. Chloroplasts

8. Cellular Respiration Goal: Convert food (C6H12O6) into energy (ATP)
Overall Reaction:
C6H12O6 + 6 O2  6 CO2 +6 H2O + ENERGY (ATP)
In the presence of oxygen: Aerobic ATP
Glycolysis
Krebs cycle
ETC
Without oxygen- Anaerobic- 2 ATP
Fermentation: Alcoholic and Lactic Acid

10. Cellular Respiration Overview
Cytoplasm
Mitochondria
Electrons
[Inner membrane]
Glycolysis
Krebs Cycle
Electron Transport Chain (ETC)
[Matrix]
Glucose
Pyruvate
34 ATP
2 ATP
Image modified from—Campbell Biology: Concepts and Connections, 5th ed. (Online textbook). Retrieved 30 March 2010 from:

11. Glycolysis First step in releasing energy
Whether oxygen is present or not
Small amount of energy is released (only 2 ATP)
Location: Cytoplasm (not in the mitochondria)
Reactants: Glucose
Products:
2 Pyruvate – 3 Carbon sugar
2 NADH (NAD+, e-, and H+) as electron carriers
4 ATP are made – 2 ATP are used = net 2ATP

13. Cellular Respiration Overview
Cytoplasm
Mitochondria
Electrons
[Inner membrane]
Glycolysis
Krebs Cycle
Electron Transport Chain (ETC)
[Matrix]
Glucose
Pyruvate
34 ATP
2 ATP
Image modified from—Campbell Biology: Concepts and Connections, 5th ed. (Online textbook). Retrieved 30 March 2010 from:
In the presence of oxygen, pyruvate will enter the mitochondria and cell respiration will continue

14. Krebs Cycle Named after Hans Krebs Also known as the Citric Acid Cycle
Pyruvate is broken down into CO2 in a series of energy extracting reactions
Takes place in the matrix (space) of the mitochondria

15. Krebs Cycle
One carbon from Pyruvate attaches to an O2 molecule forming CO2
The remaining carbons go through a series of events to release more CO2 and add e- to NAD+  NADH, and FAD+  FADH2 to fuel the next cycle
NADH and FADH2 are similar to NADPH
Reactants: Pyruvate (3 carbon sugar) & Oxygen
Products: CO2, NADH, FADH2, and 2 ATP

16. Image taken from www.sp.uconn.edu

17. Cellular Respiration Overview
Cytoplasm
Mitochondria
Electrons
[Inner membrane]
Glycolysis
Krebs Cycle
Electron Transport Chain (ETC)
[Matrix]
Glucose
Pyruvate
34 ATP
2 ATP
Image modified from—Campbell Biology: Concepts and Connections, 5th ed. (Online textbook). Retrieved 30 March 2010 from:

18. Electron Transport Chain (ETC)
Takes place on the cristae of the mitochondria
The electron carriers FADH2 and NADH take the high energy e- from glycolysis & Krebs Cycle to the ETC to convert ADP into ATP
As e- are passed from carrier to carrier, energy is used to pump H+ across the membrane of the mitochondria.
O2 acts as final carrier, adding e- to H+ forming H2O
H+, now in high concentration, diffuse through ATP Synthase, converting ADP into ATP
Form 34 ATP

20. Cellular Respiration Overview
Cytoplasm
Mitochondria
Electrons
[Inner membrane]
Glycolysis
Krebs Cycle
Electron Transport Chain (ETC)
[Matrix]
Glucose
Pyruvate
34 ATP
2 ATP
Image modified from—Campbell Biology: Concepts and Connections, 5th ed. (Online textbook). Retrieved 30 March 2010 from:

21. Anaerobic conditions lead to . . . Fermentation
What if after glycolysis, there is NO oxygen????
Anaerobic conditions lead to
Fermentation
1. Alcoholic
2. Lactic Acid
***No more ATP produced after glycolysis

22. Summary

23. Photosynthesis and Cellular Respiration “Cycle”
Products of one become reactants of the other!