1. THE LIGHT MICROSCOPE AND THE ELECTRON MICROSCOPE © 2007 Paul Billiet ODWSODWS

2. UNITS OF MEASUREMENT 1m = 10 3 mm (millimetres) 1m = 10 6 µm (micrometres) 1m = 10 9 nm (nanometres) Sometimes in old texts Angstroms (Å) are used (the diameter of a hydrogen atom) 1m = 10 10 Å © 2007 Paul Billiet ODWSODWS

3. The electromagnetic spectrum © 2007 Paul Billiet ODWSODWS

4. Light v Electron © 2007 Paul Billiet ODWSODWS

5. Magnifying using the Light Microscope © 2007 Paul Billiet ODWSODWS

6. Magnifying using the Electron Microscope © 2007 Paul Billiet ODWSODWS

7. THE LIGHT MICROSCOPE v THE ELECTRON MICROSCOPE fluorescent (TV) screen, photographic film Human eye (retina), photographic film Focussing screen VacuumAir-filledInterior MagnetsGlassLenses High voltage (50kV) tungsten lamp Tungsten or quartz halogen lamp Radiation source x500 000x1000 – x1500 Maximum magnification 0.2nm Fine detail app. 200nmMaximum resolving power Electrons app. 4nm Monochrome Visible light 760nm (red) – 390nm Colours visible Electromagnetic spectrum used ELECTRON MICROSCOPELIGHT MICROSCOPEFEATURE © 2007 Paul Billiet ODWSODWS

8. THE LIGHT MICROSCOPE v THE ELECTRON MICROSCOPE Copper gridGlass slideSupport Heavy metalsWater soluble dyesStains Microtome only. Slices  50nm Parts of cells visible Hand or microtome slices  20 000nm Whole cells visible Sectioning ResinWax Embedding OsO 4 or KMnO 4 AlcoholFixation Tissues must be dehydrated = dead Temporary mounts living or dead Preparation of specimens ELECTRON MICROSCOPE LIGHT MICROSCOPEFEATURE © 2007 Paul Billiet ODWSODWS

9. Embedding in resin © 2007 Paul Billiet ODWSODWS

10. Microtome knife © 2007 Paul Billiet ODWSODWS

11. Copper grid slides © 2007 Paul Billiet ODWSODWS

12. CELL STRUCTURE AND MICROSCOPY SUBCELLULAR STRUCTUREEUKARYOTESPROKARYOTES ANIMAL CELLSPLANT CELLS Cell wall-++ Plasma membrane+++ Nucleus & nucleoli++- Chromosomes++Circular loop of DNA Centrioles++- Mitochondria++- Plastids (chloroplasts, chromoplasts etc.)-+- Sap vacuole-+- Food vacuolesSome+- Contractile vacuolesSome+- PseudopodsSome+- CiliaSome+- FlagellaeSome Rotating Microtubules++- Lysosomes++- Golgi apparatus++- MicrovilliSome+- © 2007 Paul Billiet ODWSODWS

13. CELL STRUCTURE AND MICROSCOPY SUBCELLULAR STRUCTUREEUKARYOTESPROKARYOTES ANIMAL CELLSPLANT CELLS Endoplasmic reticulum++- Nuclear envelope & pores++- Vesicles++- Ribosomes+(bigger) +(smaller) Mesosome+++ Organelle membranes++- Macromolecular structures+++ © 2007 Paul Billiet ODWSODWS