I'm not sure.... but Manuel scalpels?
The electron transport chain is located on the inner membrane of the mitochondria, as shown below. The electron transport chain contains a number of electron carriers. These carriers take the electrons from NADH and FADH2, pass them down the chain of complexes and electron carriers, and ultimately produce ATP.
I think you meant element?
Then it is Krypton because it is in period 4 in group 18, the noble gases.