2. Complex Organic Molecules Simpler waste products w/ less energy
catabolic
pathway
ADP + P
ATP + H2O

3. LEO says GER Xe- + Y  X + Ye- Reduction = gain of e-
Oxidation = loss of e-
Y is being reduced
(oxidizing agent)
Xe- + Y  X + Ye-
X is being oxidized
(reducing agent)

4. Cellular Respiration Reduction C6H12O6 + 6 O2  6 CO2 + 6 H2O + E
Oxidation
C6H12O6 is oxidized to form CO2
O2 is reduced to form H2O
e- are used to form ATP

5. NAD+ Enzymes lower EACT so glucose is oxidized slowly.
Hydrogens stripped from glucose are not transferred directly to oxygen, but are passed to a special e- acceptor
NAD+

6. NAD+ (nicotinamide adenine
dinucleotide)
Acts as a coenzyme in the redox reaction
functions as an oxidizing agent by trapping e-
Reactions are catalyzed by enzymes called dehydrogenases

7. R–C–R’ + NAD+  R-C-R’ + NADH + H+ H
reduction
R–C–R’ + NAD+  R-C-R’ + NADH + H+ H OH O
dehydrogenase
oxidation
NAD+ = oxidized coenzyme
NADH = reduced coenzyme

8. Steps of Cellular Respiration:
1. GLYCOLYSIS
occurs in cytosol
partially oxidizes glucose (6C) into two pyruvate (3C) molecules
Energy investment phase = requires to ATP to start

9. GLUCOSE (6C)
2 ATP
2 ADP
FRUCTOSE DIPHOSPHATE (6C)
2 PGAL

10. 2 NAD
2 NADH
2 P
2 DPGA
2 ADP
2 ATP
2 PGA

11. 2 ADP
2 ATP
2 H2O
PYRUVIC ACID
Kreb’s Cycle

14. Chemical energy from glucose is still stored in the pyruvate molecules.
Fate depends on presence or absence of oxygen
If O2 is present  pyruvate enters the mitochondrion where it is completely oxidized

15. 2. KREBS CYCLE
occurs in mitochondrial matrix
complete glucose oxidation by breaking down a pyruvate derivative (acetyl Co-A) into CO2
a small amount of ATP is produced by substrate-level phosphorylation
NADH formed by transfer of e- from substrate to NAD+

16. Formation of Acetyl-CoA
CH3 OH
CO2
C=O
S-CoA
CH3
NAD+
NADH
+ H+
pyruvate
Acetyl CoA

17. A multienzyme complex catalyzes:
the removal of CO2 from the carboxyl group of pyruvate
the oxidation of the 2C fragment to acetate while reducing NAD+ to NADH
the attachment of coenzyme A to the acetyl group forming acetyl CoA

18. Krebs Cycle (Citric Acid Cycle)
oxidizes remaining acetyl fragments of Acetyl-CoA to CO2
For every turn of the Krebs cycle:
2 C enter in the acetyl fragment
2 different C are oxidized and leave as CO2
coenyzymes are reduced
3 NADH and 1 FADH2
1 ATP produced by s-l phosphorylation
oxaloacetate is regenerated

19. (6C)
(4C)
(4C)
H2O
(5C)
(4C)
ATP

20. It takes 2 turns of the Krebs cycle for complete oxidation of 1 glucose molecule.

21. CH2 COO- succinate CH2 C=O S-CoA COO- succinyl CoA CoA-SH P + ADP ATP
GDP
GTP P +
ADP
ATP

23. 3. ELECTRON TRANSPORT CHAIN
occurs at the inner membrane of the mitochondrion
accepts energized e- from reduced coenzymes (NADH and FADH2)
O2 pulls the e- down the ETC to a lower energy state
couples the exergonic slide of e- to ATP synthesis (oxidative phosphorylation – makes 90% of all ATP)

24. NADH FADH2 FMN FeS FeS CoQ NADH=3 ATP FeS FADH2=2 ATP
Cyt b
NADH=3 ATP
FeS
Cyt c
FADH2=2 ATP
Cyt c3
Cyt a
Cyt a1
Final e- acceptor
(forms water)
½ O2

25. ETC does not make ATP directly.
It generates a proton gradient across the inner mitochondrial membrane.

26. KREBS CYCLE net: (2 turns)
2 ATP by s-l phosphorylation
6 NADH
2 FADH2
4 CO2
*** most energy found in NADH and FADH2 in high energy bonds

27. TOTAL Process ATP by S-L Phos. Reduced Co-Enzyme ATP by Ox Phos. TOTAL
Glycolysis
Net 2 ATP
2 NADH
4-6 ATP
6-8 ATP
Oxidation of Pyruvate
6 ATP
Krebs Cycle
2 ATP
6 NADH
2 FADH2
18 ATP
4 ATP
24 ATP
36-38
ATP
TOTAL

28. * Prokaryotes usually get a better yield of 38 ATP because there is no membrane separating glycolysis from the ETC.
* Eukaryotes usually only get 2 ATP per NADH in glycolysis.

29. Respiratory Poisons:
Cyanide – blocks e- from cyt a3 to O2
Oligomycin (antibiotic) – inhibits ATP synthase
Dinitrophenol (DNP) – uncouples the chemiosmotic reaction so protons leak across the membrane

30. Anaerobic Respiration:
occurs if O2 is not present
there is no final e- acceptor
used by plants, fungi (yeasts) and bacteria
occurs in the cytoplasm alongside glycolysis

31. 2 PYRUVATE 2 CO2 2 ACETYLALDEHYDE 2 NADH 2 NAD+ 2 ETHANOL Alcohol
Fermentation
2 ACETYLALDEHYDE
2 NADH
2 NAD+
2 ETHANOL

32. 2 PYRUVATE
2 NADH
Lactic Acid
Fermentation
2 NAD+
2 LACTATE

34. ANAEROBIC RESPIRATION:
does not require O2
uses ETC to make ATP
uses a substance other than O2 as the final e- acceptor
ex. NO3 or SO4-2
produces ATP by oxidative phosphorylation
** occurs in only a few bacterial groups that exist in anaerobic environments

35. Strict (obligate) aerobes:
organisms that require O2 for growth and as the final e- acceptor
Strict (obligate) anaerobes:
organisms that only grow in the absence of O2, and are poisoned by it

36. FACULATIVE ANAEROBES:
organisms can grow in either aerobic or anaerobic environments
Cells can make ATP by fermentation if O2 is not available or ATP by cellular respiration if O2 is available.
PYRUVATE is common to both fermentation and respiration.

37. GLUCOSE
no O2 O2
PYRUVATE
reduced to ethanol or lactate and NAD+ is recycled as NADH is oxidized
oxidized to acetyl CoA and oxidation continues into the Krebs cycle

38. RESPIRATION CONTROLS:
Third step in glycolysis is catalyzed by the allosteric enzyme phosphofructokinase.
Ratio of ATP to ADP reflects energy status of the cell. PFK is sensitive to changes in this ratio.
Citrate and ATP are allosteric inhibitors of PFK.
When concentration rises, enzyme slows glycolysis.

39. ADP is an allosteric activator of PFK
so when ADP rises, enzyme speeds up glycolysis