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endoplasmic reticulum

(EN-doh-PLAZ-mik reh-TIH-kyoo-lum)
A network of sac-like structures and tubes in the cytoplasm (gel-like fluid) of a cell. Proteins and other molecules move through the endoplasmic reticulum. The outer surface of the endoplasmic reticulum can be smooth or rough. The rough endoplasmic reticulum has many ribosomes on its outer surface and makes proteins the cell needs. The smooth endoplasmic reticulum makes other substances that the cell needs, such as lipids (fats) and carbohydrates (sugars). The endoplasmic reticulum is a cell organelle.
Drawing showing a cell containing organelles, including the nucleus (contains DNA), the nucleolus, Golgi complex, mitochondria, and endoplasmic reticulum. Also shown are the cell membrane and a membrane receptor.Enlarge this image in new window
Parts of a cell. A cell is surrounded by a membrane, which has receptors on the surface. A cell has several small structures inside it, including the nucleus, mitochondria, endoplasmic reticulum, and Golgi complex. These all have specific functions in the cell.
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