Endomembrane System: The endomembrane system (endo– = “within”) is a group of membranes and organelles in eukaryotic cells that works together to modify, package, and transport lipids and proteins. It includes a variety of organelles, such as the nuclear envelope and lysosomes.

Components of the Endomembrane System

Here is the list of few components of the Endomembrane system which play a vital role.

1. Endoplasmic Reticulum – ER represents a network of tiny tubular structures scattered in the cytoplasm. It divides the cytoplasm into two distinct compartments – luminal (inside ER) and extraluminal (outside ER). ER is present in the cytoplasm in two forms – Rough ER (embedded with ribosomes) and Smooth ER (free from ribosomes). Rough ER helps in synthesis and secretion of proteins whereas Smooth ER synthesizes lipids.
2. Golgi bodies – Named after Camilo Golgi, the scientist who discovered them, Golgi bodies are a membraneous disc like sacs or cisternae of varying diameter between 0.5 – 1.0 µm stacked parallel like a lump of pancakes. Interconnected cis and trans faces or forming and maturing faces of cisternae are concentrically arranged around the nucleus. It serves mainly as the packaging center for endomembrane secretions like proteins.
3. Lysosomes – Infamous as the ‘suicidal bags of cell’, these are membrane-bound vesicular structures containing hydrolytic enzymes capable of digesting carbohydrates, lipids, proteins and even nucleic acids.
4. Vacuoles – The voluminous vacuole is the membrane-bound space of the cytoplasm that occupies as much as up to 90% volume of the plant cell. It contains water, sap, excretory products and other materials which are useless for the cell. The outer membrane of vacuoles, known as tonoplast, facilitates transport of ions against the concentration gradient into the vacuole. Contractile vacuoles in amoeba facilitate excretion along with transporting engulfed food via food vacuoles in some other protists.

• A membranous element of the eukaryotic cell is the endomembrane system.

• A system of suspended membranous organelles is present in the cell’s cytoplasm. Despite having various forms and activities, the organelles are referred to as a system since they are necessary for the proper operation of the cell.

• The cell membrane, vacuoles, the nuclear membrane, lysosomes, the Golgi complex, vesicles, and the endoplasmic reticulum are all organelles that collaborate (ER).

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By Team Learning Mantras