Endoplasmic reticulum (ER)

Definition

The endoplasmic reticulum (ER) is a network of membranous tubes and sacs within the cytoplasm of eukaryotic cells, involved in the synthesis, folding, modification, and transport of proteins and lipids. It exists in two forms: rough ER, studded with ribosomes, and smooth ER, which lacks ribosomes.

Related terms

Ribosomes:

Molecular structures within cells that serve as the site of protein synthesis.

Golgi apparatus:

A cell organelle that modifies, sorts, and packages proteins and lipids for storage or transport out of the cell.

Protein Synthesis:

The process in which cells build proteins based on genetic instructions