Which organelle is referred to as the powerhouse of the cell?

The mitochondria are referred to as the powerhouse of the cell because they are the primary sites of ATP (adenosine triphosphate) production through the processes of cellular respiration. This organelle is responsible for converting nutrients into energy by breaking down glucose and other substrates in the presence of oxygen. During this process, the energy released is used to form ATP, which serves as the main energy currency of the cell, powering various cellular activities.

Additionally, mitochondria have their own DNA and machinery to replicate, which supports the endosymbiotic theory of how they evolved from free-living prokaryotic organisms. Their role extends beyond energy production as they are also involved in regulating metabolism, apoptosis (programmed cell death), and maintaining cellular health. Given their essential functions in energy metabolism and cellular regulation, it is clear why mitochondria hold the title of the powerhouse of the cell.