Mitochondria are membrane-bound organelles found in eukaryotic cells, often referred to as the "powerhouses" of the cell. They are responsible for producing adenosine triphosphate (ATP), the primary energy currency of the cell, through the process of cellular respiration. Mitochondria also play key roles in regulating metabolism, calcium homeostasis, and apoptosis (programmed cell death). Each mitochondrion contains its own DNA, which is inherited maternally and allows for some degree of autonomous function.