Endoplasmic Reticulum Jen Booth, Francesca Colella, Tom Kuren and Cody Swan

 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.

 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.

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

 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. 

 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

 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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