1. CELLULAR RESPIRATION II
How Cells Obtain Energy to Sustain Life

2. CELLULAR RESPIRATION Three Major Phases: Glycolysis Krebs Cycle
3. Electron Transport Chain

3. CELLULAR RESPIRATION BEGINS IN THE CYTOPLASM
Glucose Metabolism (first part of respiration):
Starts in cytoplasm of cells of all organisms
Aerobic & Anaerobic
Glycolosis
Lysis = break down
Glyco = prefix for sugar

4. THE GLYCOLYTIC PATHWAY
Energy Input: ATP

5. THE GLYCOLYTIC PATHWAY
End product: pyruvate molecules
(Energy Output) ATP
Reduced Helper NADH

6. SUMMARY OF GLYCOLYSIS Glycolysis:
One Glucose molecule (6 C) is transformed into two (3 C) organic molecules called “pyruvate”

7. SUMMARY OF GLYCOLYSIS Additionally, the Enzyme Mediated Reactions
of Glycolysis Yield:
ATP molecules
Reduced Helper
(NADH)
(NAD+ + H & 2e-  NADH)
***NOTE: NADH is a high energy e- carrier that will become important later!***

8. TWO PATHWAYS FOLLOWING GYLCOLYSIS
In Absence of Oxygen:
Anaerobic Respiration
In Presence of Oxygen:
Aerobic Respiration

9. FERMENTATION In Absence of Oxygen: Energy production occurs
through Fermentation
Occurs in cytoplasm
Only yields 2 ATP per glucose but occurs fast

10. TWO PATHWAYS AFTER GLYCOLYSIS
In Presence of Oxygen:
Aerobic Respiration

11. AEROBIC RESPIRATION OCCURS IN MITOCHONDRIA
Transition Reactions:
Mitochondrial membrane
Krebs Cycle:
Mitochondrial matrix
Electron Transport Chain:
Inner membrane of mitochondria

12. THE TRANSITION REACTIONS
Pyruvate converted into Acetyl-CoA
Reduced helper (NADH) produced
CO2 produced

13. KREBS
CYCLE
We Continue a Series of Redox Reactions During Krebs Cycle

14. SUMMARY OF KREB’S CYCLE Kreb’s Cycle: 2 acetyl Co A produce:
Reduced helpers
ATP
CO2

15. OVERVIEW SO FAR… During Glycolysis, Transition Reactions & Krebs:
Organic molecules are oxidized
Eventually all C in glucose is found in CO2
Helper Molecules Reduced
NAD+  NADH
FAD  FADH2
Very little ATP produced

16. SUMMARY OF AEROBIC RESPIRATION

17. SUMMARY OF AEROBIC RESPIRATION SO FAR…..

18. ELECTRON TRANSPORT CHAIN
In the last phase of cellular respiration, electrons are donated to proteins in the mitochondrial inner membrane

19. ELECTRON TRANSPORT CHAIN
ETC occurs at mitochondrial inner membrane
Helper molecules donate e-s to proteins embedded in membrane

20. ELECTRON TRANSPORT CHAIN
ETC:
Series of Redox Reactions where:
Proteins pass e-s down chain
Ea. protein is more electronegative
than preceding
Oxygen is final e- acceptor
Water forms when Oxygen combines
with electrons & 2 H+ e-

21. ELECTRON TRANSPORT CHAIN
Some Proteins:
Carry electrons (only)
Carry electrons while pumping protons: H+
H+ pumped from
matrix  inter- membrane space
Creates electrochem. gradient

22. ELECTRON TRANSPORT CHAIN
Electrochemical Gradient:
Source of power for ATP synthesis!
High H+
Low H+

23. ELECTRON TRANSPORT CHAIN
ATP SYNTHESIS:
ATP synthesis is coupled to diffusion
of H+ through
ATP Synthase

24. ELECTRON TRANSPORT CHAIN
ATP Synthesis:
H+ returns to matrix
(moving down its gradient)
ATP synthase attaches inorganic phosphate to ADP
“Oxidative Phosphorylation”
ATP produced!

25. ELECTRON TRANSPORT CHAIN

26. CELLULAR RESPIRATION
Most ATP is Synthesized During the ETC

27. CONCLUSIONS: CELLULAR RESPIRATION
Cellular (aerobic) Respiration:
Involves series of redox reactions that release energy for ATP synthesis
Begins with breakdown of sugar and ends with ATP synthesis through ATP Synthase
By products include:
H2O & CO2

28. METABOLISM OF MACROMOLECULES IS TIED TO CELLULAR RESPIRATION
In absence of carbs, other molecules can be used to produce chemical energy:
Proteins
Fats