Cell organelles are specialized structures within which particular cell processes occur. Their functions are described in the following table and their structures are depicted in the illustration.
| STRUCTURE | DESCRIPTION | FUNCTION |
|---|---|---|
| STRUCTURAL ELEMENTS | ||
| Cytosketeton | Network of protein filaments | Structural support; cell movement |
| Flagella(cilia, microvilli) | Cellular extensions | Motility or moving fluids over surfaces |
| Centrioles | Hollow microtubules | Moving chromosomes during cell division |
| ENDOMEMBRANE SYSTEM | ||
| Plasma membrane | Lipid bilayer in which proteins are embedded | Regulates what passes into and out of cell; cell-to-cell communication |
| Endoplasmic reticulum | Network of internal membranes; forms compartments and vesicles | Rough type processes proteins for secretion and synthesizes phospholipids; smooth type synthesize fats and steroids |
| Nucleus | Structure bounded by double membrane; contains chromosomes | Control center of cell; directs protein synthesis and cell reproduction |
| Golgi complex | Stacks of flattened vesicles | Modifies and packages proteins for export from cell; forms secretory vesicles |
| Lysosomes | Vesicles derived from Golgi complex that contain hydrolytic digestive enzymes | Digest worn-out mitochondria and cell debris; play role in cell death |
| ENERGY-PRODUCTING ORGANELLES | ||
| Mitochondria | Bacteria-like elements with inner membrane | Power plant of the cell; site of oxidative metabolism; synthesis of ATP |
| ORGANELLES OF GENE EXPRESSION | ||
| Chromosomes | Long threads of DNA that form a complex with protein | Contain hereidtary information |
| Nucleolus | Site of rRNA synthesis | Assembles ribosomes |
| Ribosomes | Small, complex assemblies of protein, often bound to ER | Site of protein synthesis |
