The mitochondrial membrane is a crucial structure that surrounds the mitochondrion, the powerhouse of the cell. It consists of two layers: the outer membrane, which is smooth and permeable to small molecules, and the inner membrane, which is highly folded into structures called cristae. These folds increase the surface area for biochemical reactions, particularly those involved in energy production. The inner membrane contains proteins essential for the electron transport chain, a series of reactions that generate adenosine triphosphate (ATP), the energy currency of the cell. The space between the inner and outer membranes is known as the intermembrane space, while the area enclosed by the inner membrane is called the mitochondrial matrix, where various metabolic processes occur.