In prokaryotic cells, which lack membrane-bound organelles like mitochondria, the role of generating energy through cellular respiration is carried out by the cell membrane and infoldings of the cell membrane called mesosomes.

Mesosomes in prokaryotic cells play a role in cellular respiration and energy production, similar to the function of mitochondria in eukaryotic cells. The other options, spores (Option A), cysts (Option B), and nucleotides (Option C), do not directly perform the role of mitochondria in energy production.