Which part of the cell produces energy?

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

Answer: (A)

Energy in cells is produced primarily by mitochondria, often called the powerhouse of the cell. These organelles carry out cellular respiration, with the energy-yielding steps concentrated in the inner membrane where the electron transport chain and ATP synthase operate. As nutrients such as glucose are oxidized in a series of steps, most of the usable energy is captured as ATP, the cell’s energy currency, with waste products like carbon dioxide and water produced as byproducts. The folded inner membrane, or cristae, increases surface area to make this energy production more efficient. Mitochondria also contain their own DNA and ribosomes, reflecting their evolutionary origin and their ongoing role in energy metabolism.

Ribosomes, by contrast, are the protein factories of the cell; they build proteins from amino acids. The nucleus houses the genetic material and regulates cellular activities by controlling gene expression. The Golgi apparatus processes and packages proteins and lipids for distribution outside the cell or to other parts of the cell. While these structures are essential for the cell’s function, they do not primary ly generate energy, making mitochondria the correct answer.