THE LIGHT MICROSCOPE AND THE ELECTRON MICROSCOPE © 2007 Paul Billiet ODWS
UNITS OF MEASUREMENT 1m = 103 mm (millimetres) 1m = 106 µm (micrometres) 1m = 109 nm (nanometres) Sometimes in old texts Angstroms (Å) are used (the diameter of a hydrogen atom) 1m = 1010 Å © 2007 Paul Billiet ODWS
The electromagnetic spectrum © 2007 Paul Billiet ODWS
Light v Electron © 2007 Paul Billiet ODWS
Magnifying using the Light Microscope © 2007 Paul Billiet ODWS
Magnifying using the Electron Microscope © 2007 Paul Billiet ODWS
THE LIGHT MICROSCOPE v THE ELECTRON MICROSCOPE FEATURE Electrons app. 4nm Monochrome Visible light 760nm (red) – 390nm Colours visible Electromagnetic spectrum used 0.2nm Fine detail app. 200nm Maximum resolving power x500 000 x1000 – x1500 Maximum magnification High voltage (50kV) tungsten lamp Tungsten or quartz halogen lamp Radiation source Magnets Glass Lenses Vacuum Air-filled Interior fluorescent (TV) screen, photographic film Human eye (retina), photographic film Focussing screen © 2007 Paul Billiet ODWS
THE LIGHT MICROSCOPE v THE ELECTRON MICROSCOPE FEATURE Tissues must be dehydrated = dead Temporary mounts living or dead Preparation of specimens OsO4 or KMnO4 Alcohol Fixation Resin Wax Embedding Microtome only. Slices 50nm Parts of cells visible Hand or microtome slices 20 000nm Whole cells visible Sectioning Heavy metals Water soluble dyes Stains Copper grid Glass slide Support © 2007 Paul Billiet ODWS
Embedding in resin © 2007 Paul Billiet ODWS
Microtome knife © 2007 Paul Billiet ODWS
Copper grid slides © 2007 Paul Billiet ODWS
CELL STRUCTURE AND MICROSCOPY © 2007 Paul Billiet ODWS CELL STRUCTURE AND MICROSCOPY SUBCELLULAR STRUCTURE EUKARYOTES PROKARYOTES ANIMAL CELLS PLANT CELLS Cell wall - + Plasma membrane Nucleus & nucleoli Chromosomes Circular loop of DNA Centrioles Mitochondria Plastids (chloroplasts, chromoplasts etc.) Sap vacuole Food vacuoles Some Contractile vacuoles Pseudopods Cilia Flagellae Rotating Microtubules Lysosomes Golgi apparatus Microvilli
CELL STRUCTURE AND MICROSCOPY SUBCELLULAR STRUCTURE EUKARYOTES PROKARYOTES ANIMAL CELLS PLANT CELLS Endoplasmic reticulum + - Nuclear envelope & pores Vesicles Ribosomes +(bigger) +(smaller) Mesosome Organelle membranes Macromolecular structures © 2007 Paul Billiet ODWS