Which organelle is the powerhouse of the cell?

• A. Ribosome
• B. Mitochondria
• C. Nucleus
• D. Golgi apparatus

Answer: (B)

Energy for the cell’s activities comes from ATP produced by mitochondria through cellular respiration. They take in fuel like glucose and, using oxygen, drive glycolysis in the cytosol, the citric acid cycle in the matrix, and oxidative phosphorylation on the inner membrane. The cristae of that inner membrane boost surface area for the electron transport chain and ATP synthase to generate lots of ATP. Mitochondria also contain their own DNA and ribosomes, reflecting their ancient origin. Other organelles have different roles—ribosomes make proteins, the nucleus stores genetic material, and the Golgi apparatus packages and ships molecules—so mitochondria are the primary energy producers in the cell.