2. 1 : Acetyl-CoA Citrate
*Krebs cycle starts when acetyl CoA (2C) adds
its two-carbon acetyl group to oxaloacetate
(4C), producing citrate (6C) .
2 : Citrate Isocitrate
*Citrate rearranges itself to become
isocitrate.
*One water molecule is removed and another
water molecule is added.
3: Isocitrate ∝ −𝐾𝑒𝑡𝑜𝑔𝑙𝑢𝑡𝑎𝑟𝑎𝑡𝑒
* Oxidative decarboxylation of the isocitrate (6C)
produces ∝ −𝑘𝑒𝑡𝑜𝑔𝑙𝑢𝑡𝑎𝑟𝑎𝑡𝑒
* Carbon is produces and released during stage.
* Hydrogen atoms are removed from nitrates
molecules and accepted by NAD+ and becomes
NADH

3. 5. Succinyl CoA Succinate
* This is the only stage in Kreb’s cycle which GTP
(Guanossine Triphosphate) and subsequently ATP is
produced at the substrate level
* GTP is formed, the amount of energy stored the
amount of energy stuck in GTP is the same as
energy stored and ATP
4. ∝−𝑘𝑒𝑡𝑜𝑔𝑙𝑢𝑡𝑎𝑟𝑎𝑡𝑒 Succinyl Coa
*Oxidative decarboxylation of ∝−𝑘𝑒𝑡𝑜𝑔𝑙𝑢𝑡𝑎𝑟𝑎𝑡𝑒 (5C)
will produces succinate (4C).
* Carbon is produced and released during this stage.
* Hydrogen atom are removed from nitrate molecules
and accepted by NAD+ and becomes NADH.

4. 6.Succinate Fumarate
* Succinate is oxidised to fumarate
* FADH2 is formed
7. Fumarate Malate
* Additional water molecule rearranges the bond
structure of fumarate
* Fumarate is hydrated and becomes malate
8. Malate Oxaloacetate
* Malate is oxidised to produced ocaloacetate.
* NAD+ is reduced and becomes NADH.
* Oxaloacetate is generated and recycled in Krebs
cycle

5. Overall per turn, the Krebs cycle produces:
a) 3 molecules of NADH
b) 1 molecule of FADH2
C) 1 molecule of ATP (substrate- level
phosphorylation)
d) 2 molecule of CO2 (by product)
e) Krebs cycle will turn twice for every glucose
molecule. Therefore, there will be 6 molecule
of NADH, 2 molecules of FADH2, 2 molecules of
ATP and 4 molecules of CO2 as by product.