I’m not doubting it was used before the meme, I’m just doubting the ubiquity of it prior to the meme. I believe it is a bit of a Mandela effect type of thing. People remember the general purpose of mitochondria and remember their science teachers saying things similar to the effect of “powerhouse of the cell” even if they didn’t actually say that. Sort of like how “beam me up, Scotty” was specifically never used in Star Trek but just about every other variant of the phrase was.