And the space between the two membranes is called the intermembrane space. And this is found entirely in the inner mitochondrial membrane. Now, there are several important differences between these two membranes. First of all, notice that the inner membrane actually consists these folding patterns. And the folding patterns create something called the Christy. Now, Christy are these inner foldings that greatly increases the surface area on which the electron transport chain can actually lie.