Endomembrane System Notes

Endomembrane System Overview

• Network of membranes in the cell for transport functions.
• Goal: Package, transport, and export proteins.
• Transports proteins from the nucleus to the outside of the cell.

Endomembrane System Parts

• Each part facilitates protein export.

Nuclear Envelope

• Membrane surrounding the nucleus; barrier between chromosomes and cytoplasm.
• Contains pores for substance movement and RNA release.

Endoplasmic Reticulum (ER)

• Site of protein synthesis and modification.

Rough ER

• Contains ribosomes for protein synthesis.
• Modifies proteins by adding carbohydrate side chains.

Smooth ER

• No ribosomes; involved in lipid, carbohydrate, and hormone production.
• Maintains calcium ions and detoxifies cells.
• Connected to the rough ER.

Golgi Apparatus

• Processes proteins and lipids by tagging, sorting, and packaging.
• Entrance (cis face) and exit (trans face).

Vesicles

• Transport proteins and lipids through the cytoplasm.

Lysosomes

• Contain enzymes to digest old cell parts and foreign pathogens.

Vacuoles

• Digest proteins and lipids; store water and wastes (primarily in plant cells).

Importance of Endomembrane System

• Facilitates protein transport out of the cell.