Provide a detailed explanation of the role of mitochondria in cellular energy production. Your response should contain at least 3 paragraphs. Paragraphs are separated with the markdown divider: ***. Highlight at least 2 sections in your answer with markdown, i.e. *highlighted section*. In your response, the word "energy" should appear at least 3 times. At the end of your response, please explicitly add a postscript starting with *P.S.*.
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