7. Chapter 5
Overview of Metabolism
• Source of Energy (Photo- vs.
Chemotroph)
– Source of Electrons
– Carrier of Electrons
– Final Electron Acceptor
• Source of Carbon (Auto- vs.
Heterotroph)
– Auto- : Carbon Dioxide
– Hetero- : Organic Compounds
8. Chapter 5
Classification based on Metabolism
• Where microbes get their energy?
– Sunlight vs. Chemical
– Photo- vs. Chemo- trophs
• How do they obtain carbon?
– Carbon Dioxide (or inorganic cmpds.) vs.
Organic Compounds (sugars, amino acids)
– Auto- vs. Hetero- trophs
• Examples
– Photoautotrophs vs. Photoheterotrophs
– Chemoautotrophs vs. Chemoheterotrophs
11. Chapter 5
Types of -trophs
Type Energy C source Example
Photoauto- Sun CO2 Purple &
Green sulfur
bacteria
Photohetero- Sun Organic
Compounds
Purple &
Green Non-
sulfur bacteria
Chemoauto- Chemical
bonds
CO2 H, S, Fe, N
bacteria
Chemohetero- Chemical
bonds
Organic
Compounds
Most bacteria,
fungi,
protozoa,
animals
13. Chapter 5
Electron Carriers
• Photosynthesis
– NADP + H to NADPH
• Respiration
– NAD + H to NADH
– FAD + H to FADH
• Contain Niacin and Riboflavin
– Vitamins, not stable
– Can’t store these molecules
14. Chapter 5
Final Electron Acceptor
• Photosynthesis
– CO2 + H’s to CH2O
– Stores energy
• Respiration
– Aerobic
• 1/2 O2 + H 2 to H2O
– Anaerobic
• Fermentation
15. Chapter 5
Movement of Electrons
• Chemical reactions
• Oxidation Reactions
• Reduction Reactions
• Reactions Coupled
– Redox reactions
20. Chapter 5
Examples
• ATP ADP + P
– Oxidation, release energy
• ADP + P ATP
– Reduction, stores energy
• NAD + H NADH
• FADH FAD + H
• NH4 + 11/
2O2 NO2
-
+H2O + 2H + ATP
• 2H2 + O2 2H2 O
22. Chapter 5
Respiration
• Overview;
– Glucose to Carbon dioxide + Water
+Energy
– C6H12O6 + O2 6CO2 + 6H2O + 38 ATP
– Glucose is highly reduced; contains energy
– Oxygen receives the electrons to form
energy
• 4 separate reactions
– Glycolysis, Transition Reaction, Krebs
Cycle, Electron Transport, Chemiosomosis
• Requires Oxygen
23. Chapter 5
Steps in Respiration
• Electron Donors
– Organic Compounds (Glucose preferred)
• Electron Carriers
– NAD to NADH
– FAD to FADH
• Electron Acceptors-Terminal
– O2 to H2O
• Phosphorylation Reactions
– ADP to ATP
• Chemiosmosis Reactions
24. Chapter 5
Glycolysis- 10 steps
• Glucose is Phosphorylated to form
Fructose 1,6-diphosphate
• Split to form 2 Glyceraldehyde 3-
phosphate
• Final Products are:
– 2 Pyruvic Acid (C3H4O3)
• Compare to original glucose - C6H12O6
– 2 NADH
– 2 ATP
27. Chapter 5
Kreb’s Cycle
• Figure E.3, A29
• Acetyl CoA Carbon Dioxide
– C2H4O2 to CO2
– Energy produced/Acetyl CoA (x2 for
/Glucose)
• 3 NADH
• 1 FADH
• 1 ATP
• Metabolic Wheel
– Fats, amino acids, etc. enter or leave
– Citrate is product of first reaction
28. Chapter 5
Electron Transport Chain
• NADH oxidized to NAD
• FAD reduced to FADH
• Cytochromes shuffle electrons finally to
O2
– Cytochrome Oxidase important in G - ID
• H2O formed and ATP
• 3 ATP / 1 NADH
• 2 ATP / 1 FADH
39. Chapter 5
Photosynthesis
• Plants
– CO2 + H2O + Light C6H12O6 + O2
– Water is split to release electrons
• Bacteria
– H2S is used not water
• Sulfur or Sulfuric Acid formed
• Oxygen not released
– Chlorophyll is different
– Strict Anaerobe
– Purple & Green Sulfur Bacteria
40. Chemiosmosis
• Production of ATP in Electron Transport
• Electrochemical Gradient Formed
between membranes
• H+ (Protons) generated from NADH
• Electrical Force (+) & pH Force (Acid)
• Gradient formed
• ATPase enzyme that channels H+ from
High to Low concentration
– 3 ATP/NADH
– 2 ATP/NADH
Chapter 5
