BIOL1006 Lecture Notes - Lecture 22: Lipid Bilayer, Nuclear Membrane, Electron Microscope
Document Summary
The endoplasmic reticulum is a series of interconnected membranous sacs and tubules that collectively modifies proteins and synthesizes lipids. These two functions are performed in separate areas of the er: the rough er and the smooth er. The hollow portion of the er tubules is called the lumen or cisternal space. The membrane of the er, which is a phospholipid bilayer embedded with proteins, is continuous with the nuclear envelope. The rough endoplasmic reticulum is so named because the ribosomes attached to its cytoplasmic surface give it a studded appearance when viewed through an electron microscope. Ribosomes transfer their newly synthesized proteins into the lumen of the rer where they undergo structural modifications, such as folding or the acquisition of side chains. These modified proteins will be incorporated into cellular membranes-the membrane of the er or those of other organelles-or secreted from the cell. The rer also makes phospholipids for cellular membranes.
