ER (endoplasmic reticulum)

The endoplasmic reticulum (ER) is a network of membrane-bound tubes and sacs inside cells that helps produce and process proteins and lipids. It comes in two types: rough ER, which has ribosomes attached and is involved in protein synthesis, and smooth ER, which lacks ribosomes and helps build lipids and detoxify harmful substances. The ER functions as a central hub for manufacturing, folding, and distributing essential molecules, contributing significantly to the cell’s overall function and health. It's an essential part of the cell’s internal machinery, ensuring proteins and fats are correctly made and sent where needed.