What is the primary function of the mitochondria in cells?

• A. Store genetic material
• B. Generate ATP via cellular respiration
• C. Produce ribosomes
• D. Synthesize proteins for secretion

Answer: (B)

ATP production through cellular respiration is the mitochondria’s main job. Inside, the Krebs cycle and the electron transport chain use energy from nutrients to create a proton gradient across the inner mitochondrial membrane. ATP synthase then converts ADP to ATP as protons flow back through it. Oxygen acts as the final electron acceptor, allowing the chain to run efficiently and maximize ATP yield. This energy currency powers nearly every cellular process. Mitochondria do contain their own DNA and ribosomes and can synthesize a small number of proteins locally, but that isn’t their defining role. Other proteins needed for secretion are made mainly by ribosomes on the rough endoplasmic reticulum and by free ribosomes in the cytosol.