What type of membrane structure surrounds the mitochondria?

Mitochondria are surrounded by a double membrane structure, composed of two layers of phospholipids. This bilayer is essential for the mitochondria's function as it creates distinct compartments within the organelle, allowing for different biochemical processes to occur simultaneously and efficiently. The outer membrane is smooth and permeable to ions and small molecules, while the inner membrane is highly folded into structures called cristae, which house the proteins involved in the electron transport chain and ATP synthesis. This arrangement is crucial for the mitochondria’s role in cellular respiration and energy production. The presence of a double layer of phospholipids is a defining characteristic of organelles like mitochondria, distinguishing them from simpler structures that may consist of single membranes or other configurations.