BIOL 2311 Exam 2 Krebs Cycle

Condensation

2-carbon acetyl group carried by CoA is trasferred to oxaloacetate to form citrate.

Isomerization

Citrate is rearranged to isocitrate.

First Oxidation

Isocitrate is oxidized to Alpha-Ketoglutarate and one carbon is lost as CO2 and NAD+ is reduced to NADH + H+.

Second Oxidation

Alpha-Ketoglutarate is oxidized to succinyl CoA and one carbon is released as Co2, and NAD+ is reduced to NADH + H+. 

Substrate-level phosphorylation

CoA is released from succinate and this produces energy which is used to convert GDP to GTP, which powers ADP to ATP (only one made directly by this).

Third Oxidation

Succinate oxidized to fumarate, 2 e- and p+ removed and transferred to FAD to produce FADH2. 

Hydration Reaction

Fumarate converted to malate by the addition of one water molecule.

Fourth Oxidation

Malate oxidized to Oxaloacetate (reenters the cycle), reducing NAD+ to NADH and H+.