---
title: "Endomembrane System — AP Bio Definition & Exam Guide"
description: "The endomembrane system is the connected network of membranes inside eukaryotic cells that makes and ships proteins and lipids, and it's central to AP Bio's story of cell compartmentalization."
canonical: "https://fiveable.me/ap-bio/key-terms/endomembrane-system"
type: "key-term"
subject: "AP Biology"
---

# Endomembrane System — AP Bio Definition & Exam Guide

## Definition

The endomembrane system is a network of membranes within eukaryotic cells that work together to carry out various cellular processes, such as protein synthesis, lipid metabolism, and transportation of molecules. It includes organelles like the endoplasmic reticulum, Golgi apparatus, lysosomes, vacuoles, and plasma membrane.

## Review

### Related Terms

- [Endoplasmic Reticulum (ER)](/ap-bio/key-terms/endoplasmic-reticulum-er): The ER is an organelle involved in protein synthesis and lipid metabolism. It consists of interconnected membranous tubules and sacs.
- [Golgi Apparatus](/ap-bio/key-terms/golgi-apparatus): The Golgi apparatus is responsible for modifying, sorting, packaging, and transporting proteins within vesicles.
- [Lysosomes](/ap-bio/key-terms/lysosomes): Lysosomes are small vesicles filled with enzymes that break down waste materials or foreign substances in the cell.