Transcript Powerpoint Presentation:The Light Microscope and the Electron Microscope

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
Electromagnetic
spectrum used
Maximum
resolving power
Maximum
magnification
Radiation
source
Lenses
Interior
Focussing
screen
© 2007 Paul Billiet ODWS
LIGHT MICROSCOPE
ELECTRON MICROSCOPE
Visible light
Electrons
760nm (red) – 390nm
Colours visible
app. 4nm
Monochrome
app. 200nm
0.2nm
Fine detail
x1000 – x1500
x500 000
Tungsten or quartz
halogen lamp
High voltage (50kV)
tungsten lamp
Glass
Air-filled
Magnets
Vacuum
Human eye (retina),
photographic film
fluorescent (TV) screen,
photographic film
THE LIGHT MICROSCOPE v THE ELECTRON MICROSCOPE
FEATURE
Preparation of
specimens
Fixation
Embedding
LIGHT MICROSCOPE
Temporary mounts
living or dead
ELECTRON
MICROSCOPE
Tissues must be
dehydrated
= dead
Alcohol
OsO4 or KMnO4
Resin
Sectioning
Wax
Hand or microtome
slices  20 000nm
Whole cells visible
Microtome only.
Slices  50nm
Parts of cells visible
Stains
Water soluble dyes
Heavy metals
Glass slide
Copper grid
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
© 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
Some
+
-
Pseudopods
Some
+
-
Cilia
Some
+
-
Flagellae
Some
Some
Rotating
Microtubules
+
+
-
Lysosomes
+
+
-
Golgi apparatus
+
+
-
Some
+
-
Microvilli
CELL STRUCTURE AND MICROSCOPY
SUBCELLULAR STRUCTURE
EUKARYOTES
PROKARYOTES
ANIMAL CELLS
PLANT CELLS
Endoplasmic reticulum
+
+
-
Nuclear envelope & pores
+
+
-
Vesicles
+
+
-
Ribosomes
+(bigger)
+(bigger)
+(smaller)
Mesosome
+
+
+
Organelle membranes
+
+
-
Macromolecular structures
+
+
+
© 2007 Paul Billiet ODWS