Bioenergetics

Calculation For Energy (Atp ) Generated By Fatty Acid Oxidation , Tca Cycle , Glycolysis & Pdh System

I) Basic Rules-

A) Energetics Of Glycolysis-

1. Energy Production Steps-

     2nadh2= 2× 2.5 Atp (New) &  2× 3 Atp (Old)= 5 Atp (New) &  6 Atp (Old) - For Aerobic Glycolysis

     Substrate Level Phosphorylation = 2× 2atp = 4 Atp

     Total= 9 Atp (New) &  10 Atp (Old)-aerobic Glycolysis

                   = 4 Atp - Anerobic Glycolysis

2. Energy Utilizing Steps-
    
     2× 1atp = 2atp

3. Net Atp Produced-

     For Aerobic Glycolysis-   9 Atp (New) &  10 Atp (Old) - 2atp= 7 Atp (New) &  8 Atp (Old)

     For Anerobic Glycolysis - 4 Atp - 2atp = 2atp

B) Energetics Of Pyruvate Dehydrogenase Complex-
     
      Energy From Conversion Of 2 Moles Of Pyruvate To Acetyl Coa (Aerobic Respiration) = 2× 1nadh2= 2nadh2

      Net Energy Yield= 2nadh2 = 2× 2.5 Atp (New) & 2 × 3 Atp (Old) = 5 Atp (New) & 6 Atp (Old)

C. Energetics Of Tca Cycle-each Cycle With 1acetyl Coa Metabolism Produces-

        3nadh2 =  3 × 2.5  Atp (New) & 3×3 Atp (Old) = 7.5  Atp (New) & 9 Atp (Old)

        1fadh2 =   1× 1.5  Atp (New) & 1×2 Atp (Old)  = 1.5 Atp (New) &  2 Atp (Old)

         Substrate Level Phosphorylation- 1 Gtp Formed Which Is Converted To Atp Via Adp
          Gtp + Adp = Atp + Gdp
        Thus 1atp
 
Net Yield Of Atp Per Turn ( 1mol Of Acetyl Coa) =  10 Atp (New) &  12 Atp (Old)

Thus Total Atp In Tca Cycle  Per  Molecule Of Glucose = 2 Acetyl Coa =2× 10/12= 20 Atp (New) &  24 Atp (Old)

D) Thus Net Yield Of Atp When 1molecule Of Glucose Is Completely Oxidised  Aerobically-

   1. From Aerobic Glycolysis= 7 Atp (New) &  8 Atp (Old)

   2. From Pdh Complex= 5 Atp (New) & 6 Atp (Old)

   3. From Tca Cycle= 20 Atp (New) &  24 Atp (Old)

  Net Atp Produced= 32 Atp (New) &  38 Atp (Old)

E) Energetics Of Fatty Acid Oxidation-

1. Initial Activation Req 2 Atp= (-2atp)

2. Each Cycle Removes 1acetyl Coa & Produces-

                 1fadh2=1.5 Atp (New)  & 2 Atp (Old)

                 1 Nadh2= 2.5 Atp (New) & 3 Atp (Old)

                   Total = 4  Atp (New) & 5 Atp (Old)

3. Thus Each Cycle Produces 4 Atp (New) & 5 Atp (Old) & 1 Acetyl Coa

4. Each Mole Of Acetyl Coa Produces 10 Atp (New) &  12 Atp (Old) In Tca Cycle

5. Now Taking  Example Of Say Palmitic Acid- (C16) Saturated Fatty Acid

     It Undergoes  7 Cycles Of Beta Oxidation To Produce 8 Moles Of Acetyl Coa

     Thus Atp From 7 Cycles = 7× 4 Atp (New) & 5 Atp (Old)= 28 Atp (New) & 35 Atp (Old)

     And Atp From 8 Acetyl Coa Via Tca Cycle= 8× 10 Atp (New) &  12 Atp (Old)= 80 Atp (New) &  96 Atp (Old)

    ★★★finally Net Atp From 1 Palmitic Acid=
                
    28 Atp (New) &  35 Atp (Old) + 80 Atp (New) &  96 Atp (Old) - 2atp (For Initial Activation)= 106 Atp (New) &  129 Atp (Old) ★★★