Krebs
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Transcript of Krebs
After Glycolysis we have: 2 NADH, 4 ATP2 Pyruvate (3C)
Process was Anaerobic & took place in the cytoplasm of ALL cells
No O2 is required and the yield of ATP from a molecule of glucose is relatively small
What is the fate of pyruvate?
Fate of PyruvateIn order to keep glycolysis going the NADH formed must be
oxidized back to NAD+. This can be done Aerobically (with O2) or Anaerobically (without O2)
The Mitochondrion
Double Membrane
Possesses its own DNA (mtDNA)
Inner Membrane is folded into CRISTAE
Space inside the Inner Membrane is known as the MATRIX
Site of AEROBIC RESPIRATION
Krebs or Citric Acid Cycle
Electron Transport Chain
The Krebs Cycle
Final Breakdown of Glucose
• Production of CO2
Series of REDOX Reactions
•LEO GER
Occurs in the Matrix
Transition Reaction
Oxidation of Pyruvate (3C -> 2C)– Pyruvate is Oxidized– NAD+ --> NADH
– CO2 removed (COO-) & Co-A added
STEP 3: OXIDATION & De-Carboxylation
•Isocitrate is oxidized: NAD+ is reduced to NADH
•Carboxyl group -COO- is removed and exits as CO2
•6C --> 5C α-Ketoglutarate
STEP 4: OXIDATION & De-Carboxylation
∀α-Ketoglutarate is oxidized & NAD+ is reduced to NADH
•Again -COO- is removed as CO2
•Co-enzyme A is attached again
•5C --> 4C Succinyl-CoA
STEP 5:
•CoA is replaced by a PO4 group
•Succinyl-CoA (4C) --> Succinate (4C)
•PO4 group is then passed to GDP -> GTP
•GTP is then transformed into ATP
•In prokaryotes & plants ATP is made directly in this step
STEP 6: OXIDATION
•Succinate is oxidized & electrons are transferred to FAD+ to form FADH2
•FADH2 is similar to NADH and goes to the ETC
FAD+ = flavin adenine dinucleotide … comes from riboflavin (B-Vitamin)
•Succinate (4C) --> Fumarate (4C)
STEP 8: OXIDATION
•Malate is oxidized to form Oxaloacetate which can regenerate the Krebs Cycle
•NAD+ is reduced to NADH
Final Notes1. Book-Keeping
– For each pyruvate:• 4 NADH formed, 1 FADH2
• 1 ATP (as GTP)• Double this to get the total for 1 glucose molecule
1. Carbons– It takes 3 turns of the Krebs cycle for the 1st set of
C’s from acetyl-CoA to be removed
1. Where’s the Oxygen???