The structures of chloroplast and mitochondria are similar. Both organelles consist of a smooth outer membrane, folded inner membrane (in chloroplasts called lamellae, in mitochondria called cristae), and fluid intracellular space (in chloroplast called stroma, in mitochondria called matrix). Only these structures allow those organelles to perform their function. The presence of folded inner membranes enables a formation of compartments inside the organelles. Differences in concentrations of hydrogen ions in those compartments are important for photosynthesis in chloroplasts and cellular respiration in mitochondria.
