Which organelle is known as the powerhouse of the cell?

The mitochondria are often referred to as the powerhouse of the cell because they are the primary site of energy production through the process of cellular respiration. In this organelle, nutrients are converted into adenosine triphosphate (ATP), which is the main energy carrier in cells. This ATP production is critical for fueling various cellular activities and functions, enabling the cell to maintain its vital processes, such as muscle contraction, nerve impulse propagation, and biosynthesis.

In contrast, other organelles such as the nucleus play a key role in storing and managing genetic information but do not produce energy. Ribosomes are responsible for protein synthesis, translating the genetic code into proteins but again do not generate energy. The endoplasmic reticulum is involved in the synthesis of lipids and proteins, and it also plays a role in transporting these molecules, but it is not a direct source of cellular energy. Thus, the specific function of mitochondria in energy production solidifies their title as the powerhouse of the cell.