the endoplasmic reticulum is found in cytosol in plants and animals.
the endoplasmic reticulum is found in cytosol in plants and animals.
is the endoplasmic reticulum found in plants or animals?
cytosol
in most cells the smooth endoplasmic reticulum (abbreviated ser) is scarce. instead there are areas where the er is partly smooth and partly rough, this area is called the transitional er. the transitional er gets its name because it contains er exit sites. these are areas where the transport vesicles that contain lipids and proteins made in the er, detach from the er and start moving to the golgi apparatus. specialized cells can have a lot of smooth endoplasmic reticulum and in these cells the smooth er has many functions. it synthesizes lipids, phospholipids, and steroids. cells which secrete these products, such as those in the testes, ovaries, and sebaceous glands have an abundance of smooth endoplasmic reticulum. it also carries out the metabolism of carbohydrates, detoxification of natural metabolism products and of alcohol and drugs, attachment of receptors on cell membrane proteins, and steroid metabolism. in muscle cells, it regulates calcium ion concentration. smooth endoplasmic reticulum is found in a variety of cell types (both animal and plant), and it serves different functions in each. the smooth endoplasmic reticulum also contains the enzyme glucose-6-phosphatase, which converts glucose-6-phosphate to glucose, a step in gluconeogenesis. it is connected to the nuclear envelope and consists of tubules that are located near the cell periphery. these tubes sometimes branch forming a network that is reticular in appearance. in some cells, there are dilated areas like the sacs of rough endoplasmic reticulum. the network of smooth endoplasmic reticulum allows for an increased surface area to be devoted to the action or storage of key enzymes and the products of these enzymes.
endoplasmic reticulum
the membrane of the rough endoplasmic reticulum forms large double membrane sheets that are located near, and continuous with, the outer layer of the nuclear envelope. the double membrane sheets are stacked and connected through several right or left-handed helical ramps, the so-called terasaki ramps, giving rise to a structure resembling a multi-storey car park. although there is no continuous membrane between the endoplasmic reticulum and the golgi apparatus, membrane-bound transport vesicles shuttle proteins between these two compartments. vesicles are surrounded by coating proteins called copi and copii. copii targets vesicles to the golgi apparatus and copi marks them to be brought back to the rough endoplasmic reticulum. the rough endoplasmic reticulum works in concert with the golgi complex to target new proteins to their proper destinations. a second method of transport out of the endoplasmic reticulum involves areas called membrane contact sites, where the membranes of the endoplasmic reticulum and other organelles are held closely together, allowing the transfer of lipids and other small molecules.
endoplasmic reticulum