How is the structure of the mitochondrion well adapted for the activities it carries out?

Much of respiration takes place in the mitochondria. Mitochondria have a double membrane: the outer membrane contains many protein channels, which let almost any small molecule through; while the inner membrane is more normal and is impermeable to most materials. The inner membrane is highly folded into folds called cristae, giving a larger surface area. The electron microscope reveals blobs on the inner membrane, which were originally called stalked particles. These have now been identified as the enzyme complex that synthesises ATP, are is more correctly called ATP synthase. the space inside the inner membrane is called the matrix, and is where the Krebs cycle takes place (the matrix also contains DNA and some genes are replicated and expressed here).