Which organelle is known as the powerhouse of the cell?

The mitochondria are known as the powerhouse of the cell because their primary function is to produce adenosine triphosphate (ATP), which is the energy currency of the cell. This process occurs through cellular respiration, where mitochondria convert biochemical energy from nutrients into ATP, powering various cellular functions. The inner membrane of mitochondria contains enzymes essential for the electron transport chain and ATP synthesis, highlighting their central role in energy metabolism.

In contrast, the nucleus is responsible for storing and transmitting genetic information; ribosomes are the sites of protein synthesis; and chloroplasts are involved in photosynthesis in plant cells, converting sunlight into chemical energy. Each of these organelles plays a vital role in the cell, but none are directly involved in ATP production in the way that mitochondria are.