Which organelle is known as the "powerhouse of the cell"?

The mitochondria are known as the "powerhouse of the cell" because they are the primary sites for cellular respiration, a crucial process that converts biochemical energy from nutrients into adenosine triphosphate (ATP), the energy currency of the cell. This energy production is essential for various cellular functions and activities, supporting everything from muscle contraction to nerve impulse transmission.

Mitochondria have a unique double membrane structure that facilitates the various stages of aerobic respiration, allowing for efficient conversion of energy stored in food molecules into usable energy forms. Their role in generating ATP is fundamental, as ATP is required for many metabolic processes within the cell.

Other organelles, while vital to cell function, serve different purposes. For example, the endoplasmic reticulum is involved in the synthesis and processing of proteins and lipids, lysosomes contain enzymes for digestion and waste processing, and chloroplasts, found in plant cells, are responsible for photosynthesis rather than energy production through respiration.