The powerhouse of the cell is the mitochondrion. Mitochondria are double-membraned organelles that convert nutrients into adenosine triphosphate (ATP) through cellular respiration. They are crucial for providing energy to the cell, which is essential for various cellular functions, such as growth, metabolism, and repair. Mitochondria also play roles in regulating cellular metabolism and apoptosis (programmed cell death). Their ability to produce energy makes them vital for the overall functioning and survival of eukaryotic cells.