Mitochondrion (pl. Mitochondria): Spherical or elongated structures found in most eukaryotic cells that produce most of the ATP in the cell.

Golgi apparatus (golgi body): In eukaryotic cells, a series of flattened, hollow sacs surrounded by phospholipid bilayers and functioning to package large molecules for export in secretory vesicles.

Vacuole: General term for a membranous sac that stores or carries a substance in a cell.

Cytoplasm: General term used to describe the semiliquid, gelatinous material inside a cell.

Endoplasmic Reticulum: Netlike arrangement of hollow tubules continuous with the outer membrane of the nuclear envelope and functioning as a transport system.

Nucleus: Spherical to ovoid membranous organelle containing a eukaryotic cell’s primary genetic material.