Week 2: Bacterial Metabolism

• - degrade complex molecules to smaller molecules to release energy
• 
  - produce energy-storage molecules
• i.e., ATP, GTP, NADH, FADH2

- examples: glycolysis, TCA cycle, fermentation, etc

- energy used to synthesize new molecules and structures

- use energy-storage molecules

- examples: most biosynthesis, e.g., nucleic acid, proteins, lipopolysaccharides, peptidoglycan etc

primary molecules, yielding energy by phosphatase

1. Adenosine triphosphate (ATP)

     ATP  ->  ADP +  Pi + energy 

2. Guanosine triphosphate (GTP)

    GTP  ->    GDP +  Pi  + energy

ATP

Secondary molecules, yielding ATP from the electron transport chain (ETC)

1. reduced nicotinamide-adenine dinucleotide (NADH)

  NADH  = 3 ATP

2. reduced flavin adenine dinucleotide (FADH2)

  FADH2 =  2 ATP

1.Glycoylsis

2.Fermentation

• 1) Glycolysis
• 2) ETC
• 3) Krebs cycle

- aka Embden-Meyerhof-Parnas, EMP pathway

- occurs in both aerobic and anaerobic condition

-End product of glycolysis: 2 pyruvate

In aerobic: TCA cycle

In anaerobic: fermentation

• only in aerobic condition

•pyruvate is a key molecule to enter TCA cycle

•produces most various energy-storage molecules, e.g GTP, NADH, FADH2

•functions as common pathway for oxidation of amino acids, fatty acids, carbohydrates

• -  aerobic condition
• -  acts as a bank that cashes out energy

• - 3 ATP generated from 1NADH
• - 2 ATP generated from 1 FADH2

   34 ATP (ETC)

   2 ATP (glycolysis)

+ 2 GTP (TCA cycle)

38 ATP / mole glucose

• Anaerobic bacteria are less efficient at energy production than aerobic bacteria.

• anaerobic glucose catabolism produces only 2 ATP molecule per glucose.

•Conversion of pyruvic acid to organic acids & alcohols

•These end-products are useful for identification of bacteria and in industrial processes.

• Pentose-phosphate pathway
• – glucose to pentose bypassing glycolysis

• Entner-Duodoroff pathway
• - only in prokaryotic

–glucose to pyruvate and glyceraldehyde -3 phosphate

–mostly in obligate aerobic bacteria

- produces key intermediates for the ultimate synthesis of:

• amino acids
• lipids
• purines and pyrimidines