The main purpose of mitochondria in cells is to generate adenosine triphosphate (ATP), the primary energy currency of the cell. Often referred to as the "powerhouses" of the cell, mitochondria convert energy stored in food molecules, such as glucose, through processes like cellular respiration. This process involves a complex series of chemical reactions, including the Krebs cycle and oxidative phosphorylation, where energy is harvested and transformed into a usable form for cellular activities. Besides energy production, mitochondria are also involved in regulating metabolic pathways, maintaining calcium homeostasis, and initiating apoptosis, or programmed cell death.