Endoplasmic reticulum (ER)

Definition

The endoplasmic reticulum (ER) is a network of membranous tubules and sacs found within eukaryotic cells. It plays a crucial role in the synthesis, folding, modification, and transport of proteins and lipids.

5 Must Know Facts For Your Next Test

1. The ER has two distinct regions: the rough ER (RER), which is studded with ribosomes, and the smooth ER (SER), which lacks ribosomes.
2. The rough ER is primarily involved in protein synthesis and quality control.
3. The smooth ER is responsible for lipid synthesis, detoxification processes, and calcium storage.
4. Proteins synthesized in the rough ER are often destined for secretion or for use in the cell membrane.
5. The endoplasmic reticulum works closely with the Golgi apparatus to ensure proper processing and delivery of cellular products.

Review Questions

• What are the main functions of the rough endoplasmic reticulum?
• How does the structure of the smooth ER differ from that of the rough ER?
• In what ways do the endoplasmic reticulum and Golgi apparatus collaborate within a cell?

Related terms

Golgi Apparatus: An organelle that modifies, sorts, and packages proteins and lipids for secretion or delivery to other organelles.

Ribosome: A molecular machine found within all living cells that synthesizes proteins by translating messenger RNA.

Lysosome: A membrane-bound organelle containing enzymes that break down waste materials and cellular debris.