Complex I 

Complex 1 (NADH-Q dehydrogenase) 

-Entry for NADH electrons 

-Contains ion-sulfur clusters and FMN

-Pumps 4 H+

1. NADH donates its electrons to FMN

   1. FMN is unstable, and wants to take in hydrogens. Therefore, it takes 2 hydrogens from NADH to stabilize itself with the two extra electrons. 

2. The electrons move on to the series of Fe-S clusters that quickly move the two electrons around, generating an electric current. 

   1. This allows for the pumping of 4 H+ ions into the inner membrane space. 

   2. Following the removal of the e- from FMN, it loses the two hydrogens it took up to the matrix. 

3. The final Fe-S cluster attracts coenzyme Q (UQ → ubiquinone) and gives it the two e-. This causes it to associate 2 hydrogens similar to the FMN.