s: (1) Nucleolus (2) Nucleus (3) Ribosomes (4) Vesicle (5) Rough endoplasmic reticulum (ER) (6) Golgi apparatus (7) Cytoskeleton (8) Smooth ER (9) Mitochondria (10) Vacuole (11) Cytoplasm (12) Lysosome (13) Centrioles within centrosome]] In cell biology, a mitochondrion (plural mitochondria) is a membrane-enclosed organelle found in most eukaryotic cells. These organelles range from 0.5 to 10 micrometers (μm) in diameter. Mitochondria are sometimes described as "cellular power plants" beca… (More on Mitochondria)