why are mitochondria called the powerhouse of the cell?

Mitochondria are called the powerhouse of the cell because they generate the majority of the cell's energy in the form of adenosine triphosphate (ATP). They carry out cellular respiration, a multi-step process that converts biochemical energy from nutrients into ATP, which powers various cellular activities. Mitochondria have a unique double-membrane structure that facilitates these energy-producing reactions, including the Krebs cycle and electron transport chain. This energy production is vital for many cell functions such as muscle contraction, nerve impulses, and biosynthesis. Beyond energy, mitochondria also regulate cell death and store calcium, contributing to overall cellular health. Because over 90% of the ATP used by cells is produced by mitochondria, they are fittingly called the cell's powerhouse.