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Endoplasmic Reticulum Jen Booth, Francesca Colella, Tom Kuren and Cody Swan
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All E.R. has an extensive membrane network of cisternae (sac-like structures) held together by the cytoskeleton The inner spaces of these membranes are called “lumen” The phospholipid membrane encloses a space, the cisternal space (or lumen), which is continuous with the perinuclear space but separate from the cytosol. Appears to be rough through the electron microscope because ribosomes stud the cytoplasmic surface of the membrane Rough E.R. also has ribosomes attached to the cytoplasmic side of the nuclear envelope’s outer membrane, which is confluent with rough E.R.
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Functions of any E.R. vary depending on the type of E.R. and the type of cell in which it resides In Rough E.R., the ribosomes produce proteins which are secreted by the specialized cell and are vital to life processes Most proteins secreted from these specialized cells are glycoproteins which covalently bond to carbohydrates This carbohydrate appendage is a small polymer of sugar units Some proteins in the E.R., produced by free ribosomes, remain in the cytosol of the E.R.
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Shape Extensive membrane of cisternae – sac-like structures Held together by one cytoskeleton Not covered in ribosomes, thus it appears smooth Composition Structure Resembles a network of tubes Composed of a phospholipid bilayer TEM of smooth endoplasmic reticulum
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Functions in diverse processes, including synthesis of lipids, metabolism of carbohydrates, and detoxification of drugs and poisons Therefore, Smooth E.R. is vital to the production of steroids and hormones Structures that secrete hormones are usually rich in smooth E.R.
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Enzymes from the E.R. of liver cells remove phosphate from glucose, which can then leave the liver cells to perform necessary tasks (in carbohydrate metabolism) In the detoxification process, E.R. and its enzymes actually increase tolerance of the body Smooth E.R. also functions in muscles as they do work
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What is not a function associated with Smooth E.R.? A. Synthesis lipids A. Synthesis lipids B. metabolism of carbs B. metabolism of carbs C. detox of drugs and poisons C. detox of drugs and poisons D. make its own membrane for phospholipids D. make its own membrane for phospholipids
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http://www.glogster.com/media/3/6/69/65/6696543.jpg http://php.med.unsw.edu.au/cellbiology/index.php?title= File:Smooth_endoplasmic_reticulum_tem.jpg http://php.med.unsw.edu.au/cellbiology/index.php?title= File:Smooth_endoplasmic_reticulum_tem.jpg
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