Which organelle is responsible for producing ATP, the energy currency of the cell?

Mitochondria are known as the powerhouse of the cell because they play a crucial role in producing ATP (adenosine triphosphate), which serves as the primary energy carrier in all living cells. The process of ATP production occurs through cellular respiration, specifically in the inner membrane of the mitochondria, where glucose and oxygen are utilized to generate ATP. This energy is essential for various cellular functions, including metabolic processes, muscle contraction, and active transport.

The other organelles listed do not produce ATP. For example, the nucleus is involved in storing genetic information and regulating gene expression, while ribosomes are responsible for protein synthesis. The endoplasmic reticulum is involved in the synthesis of proteins and lipids, along with other cellular processes. Therefore, the mitochondria are uniquely fitted for the task of ATP production, making them fundamental to energy metabolism in the cell.