Which organelle is commonly referred to as the powerhouse of the cell?

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

Answer: (A)

Energy production inside the cell is dominated by mitochondria because they generate most of the ATP, the cell’s energy currency, through cellular respiration. In these organelles, nutrients are processed through a sequence: the TCA cycle and the electron transport chain in the inner membrane oxidize substrates and transfer electrons, creating a proton gradient that powers ATP synthase to make ATP. The inner membrane’s folds, called cristae, increase surface area to maximize this energy production efficiency. Mitochondria also contain their own DNA and ribosomes, reflecting their evolved role as energy factories that can operate somewhat independently.

The nucleus stores and protects genetic material and governs cellular activities, not energy production. Ribosomes synthesize proteins, not ATP. Golgi apparatus modifies and ships proteins and lipids, also not a primary source of ATP.