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what is endoplasmic reticulum

Endoplasmic reticulum , or ER , is an interconnected network of membranous structureslike tubules, vesicles, and cisternae . Cisternae are the flattened disk-like membranous structures. Tubules are tubular in shape, while vesicles are sac-like structures.

There are two types of endoplasmic reticulum, namely smooth endoplasmic reticulum (SER) and rough endoplasmic reticulum (RER) . When ribosomes get attached to the surface of smooth endoplasmic reticulum, it becomes rough endoplasmic reticulum.

Functions of smooth endoplasmic reticulum

  • Smooth ER synthesizes fats and lipids.

  • It also takes part in the metabolism of carbohydrates.

  • It actively participates in drug detoxification.

  • It maintains the calcium ion concentration in the cytosol.

Functions of rough endoplasmic reticulum

  • Most of the lysosomal proteins are produced in the rough ER.

  • It transports proteins to various destinations like the plasma membrane.

  • This is the major site of glycosylation (addition of carbohydrates in proteins).

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The

endoplasmic reticulum

(

ER

) is an

organelle

of

cells

in

eukaryotic organisms

that forms an interconnected network of membrane vesicles. According to the structure, the endoplasmic reticulum is classified into two types,

rough endoplasmic reticulum (RER)

and

smooth endoplasmic reticulum (SER)

. The rough endoplasmic reticulum is studded with

ribosomes

on the

cytosolic

face. These are the sites of

protein synthesis

. The rough endoplasmic reticulum is predominantly found in

hepatocytes

where protein synthesis occurs actively. The smooth endoplasmic reticulum is a smooth network without the ribosomes. The smooth endoplasmic reticulum is concerned with

lipid metabolism

,

carbohydrate metabolism

, and

detoxification

. The smooth endoplasmic reticulum is abundant in mammalian liver and gonad cells. The lacey membranes of the endoplasmic reticulum were first seen in 1945 by

Keith R. Porter

,

Albert Claude

, and Ernest F. Fullam.

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Endoplasmic Reticulum - Wrapping it UpAnotherorganellein the cell is theendoplasmic reticulum(ER). While the function of thenucleusis to act as the cell brain, the ER functions as apackaging system. It does not work alone. The ER works closely with theGolgi apparatus,ribososmes, RNA, mRNA, and tRNA. It creates a network of membranes found through the whole cell. The ER may also look different from cell to cell, depending on the cell's function.Rough and SmoothAs you learn more about cells you will discover two types of ER. There are rough ER and smooth ER. They both have the same types of membranes but they have different shapes and rough ER has ribosomes attached. Rough ER looks like sheets of bumpy membranes while smooth ER looks more like tubes. Sometimes the ER looks like a flat balloon. Sacs of the ER calledcisternaestore the complex molecules.Smooth ERhas its purpose in the cell. It acts as a storage organelle. It is important in the creation and storage ofsteroids. It also storesionsin solution that the cell may need at a later time. Steroids are a type of ringed organic molecule used for many purposes in an organism. They are not always about building muscle mass like a weight lifter. The ion storage is important because sometimes a cell needs ions fast. It might not want to search the environment for ions, so it is easier to have them stored in a pack for easy use.Rough ERwas mentioned in the section on ribosomes. They are very important in the synthesis and packaging ofproteins. Some of those proteins might be used in the cell and some are sent out. The ribosomes are attached to the membrane of the ER. As the ribosome builds the amino acid chain, the chain is pushed into the ER. When the protein is complete, the rough ER pinches off a vesicle. That vesicle, a small membrane bubble, can move to thecell membraneor the Golgi apparatus.
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