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

2. 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

3. The electromagnetic spectrum
© 2007 Paul Billiet ODWS

4. Light v Electron
© 2007 Paul Billiet ODWS

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

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

7. 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 x
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

8. 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  nm
Whole cells visible
Sectioning
Heavy metals
Water soluble dyes
Stains
Copper grid
Glass slide
Support
© 2007 Paul Billiet ODWS

9. Embedding in resin
© 2007 Paul Billiet ODWS

10. Microtome knife
© 2007 Paul Billiet ODWS

11. Copper grid slides
© 2007 Paul Billiet ODWS

12. 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

13. 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