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CHAPTER 7 CELL STRUCTURE & FUNCTION PGS. 168 - 199 CELL STRUCTURE & FUNCTION ANTON VAN LEEUWNENHOEK One of the first person’s to use a microscope. Looked at pond water and saw small organisms. ROBERT HOOKE Looked at plant tissues in 1665. He specifically looked at cork. Looked like tiny chambers he called “cells” Microscopy Today: Compound Light Microscope Light passed through specimen Focused by glass lenses Image formed on human retina Max magnification about 1000X Resolves objects separated by 0.2 mm, 500X better than human eye 4 Compound Light Microscope Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 85 µm amoeba, light micrograph eye ocular lens light rays objective lens specimen condenser lens light source a. Compound light microscope © Robert Brons/Biological Photo Service 5 Microscopy Today: Transmission Electron Microscope Abbreviated T.E.M. Electrons passed through specimen Focused by magnetic lenses Image formed on fluorescent screen Similar to TV screen Image is then photographed Max magnification 1000,000sX Resolves objects separated by 0.00002 mm, 100,000X better than human eye 6 Transmission Electron Microscope Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 200 nm pseudopod segment, transmission electron micrograph electron source electron beam electromagnetic condenser lens specimen electromagnetic objective lens electromagnetic projector lens observation screen or photographic plate b. Transmission electron microscope © M. Schliwa/Visuals Unlimited 7 Microscopy Today: Scanning Electron Microscope Abbreviated S.E.M. Specimen sprayed with thin coat of metal Electron beam scanned across surface of specimen Metal emits secondary electrons Emitted electrons focused by magnetic lenses Image formed on fluorescent screen Similar to TV screen Image is then photographed 8 Scanning Electron Microscope Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 500µm amoeba, scanning electron micrograph electron gun electron beam electromagnetic condenser lenses scanning coil final condenser lens secondary electrons specimen electron detector TV viewing screen c. Scanning electron microscope © Kessel/Shih/Peter Arnold, Inc. 9 Microscopy and Amoeba proteus Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 85 µm amoeba, light micrograph eye ocular lens light rays electron source electron beam electromagnetic condenser lens specimen electromagnetic objective lens objective lens 500µm 200 nm pseudopod segment, transmission electron micrograph amoeba, scanning electron micrograph electron gun electron beam electromagnetic condenserl enses scanning coil specimen condenser lens electromagnetic projector lens observation screen or photographic plate light source a. Compound light microscope b. Transmission electron microscope final Condenser lens secondary electrons specimen electron detector TV Viewing screen c. Scanning electron microscope a: © Robert Brons/Biological Photo Service; b: © M. Schliwa/Visuals Unlimited; c: © Kessel/Shih/Peter Arnold, Inc. 10