Flexi Says: Most eukaryotes have mitochondria, while every multi-cellular eukaryote does. However, a few one-celled eukaryotes lack mitochondria. These eukaryotes live as parasites. Additionally, some multicellular eukaryotes lack mitochondria in specific cells. For example, human red blood cells lack mitochondria, an adaptation that either reduces the cells' size or prevents them from using the oxygen they carry. Prokaryotes lack any membrane-bound organelles, including mitochondria.
