Which organelle is the site of cellular respiration and is commonly called the powerhouse of the cell?

• A. Nucleus
• B. Mitochondrion
• C. Chloroplast
• D. Golgi apparatus

Answer: (B)

Cellular respiration is the process that converts fuel-derived energy into ATP, the cell’s usable energy. The organelle that carries out most of this work is the mitochondrion. It’s specialized for energy production: the inner membrane is folded into cristae, dramatically increasing surface area for the electron transport chain and ATP synthase, which together drive most ATP generation during oxidative phosphorylation. The mitochondrial matrix hosts the Krebs cycle enzymes, and the organelle can even contain its own DNA and ribosomes, reflecting its long-standing role in energy metabolism. Because of these features, mitochondria are where the bulk of ATP is produced, earning them the nickname powerhouse of the cell. Other organelles have different jobs: the nucleus stores genetic material and coordinates activities, chloroplasts (in plants and some algae) carry out photosynthesis to make sugars, and the Golgi apparatus processes and ships proteins.