Question

Where in the mitochondrion does the electron transport chain take place?

Answer 1

The inner mitochondrial membrane.

Explanation:

The mitochondrion has an outer membrane and an inner membrane with folds (cisternae). The electron transport chain is a series of transmembrane proteins found in the inner membrane.

The electrons are shuttled between these proteins which is used to pump protons (`H^+`) to the space between the inner and the outer membrane. This creates a gradient that is used to finally produce ATP = energy ready to go!