Transcript Bacterial Classification

Microscopy
History
 Compound Light Microscopes
 Types of Microscopy
 Measurement Systems
 Measuring in a Microscope
 Staining Procedures
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Microscopy
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Early History of Devices that Alter Light:
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Claudius Ptolemy (2nd Century B.C.)
» Described refraction water
Seneca (1st Century A.D.)
» Described magnification by a globe of water
Alhazen (962-1038 A.D.)
» Described optical principles & anatomy of eye
Roger Bacon (1267 A.D.)
» Described simple magnification
Microscopy
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Lenses first derived were used to
improve eyesight
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Pliny the Elder wrote of Nero’s use of
emeralds to watch gladiators
Reinvention of spectacles occurred around
1280 to 1285 in Florence, Italy
Dutch spectacle maker Zaccharias Jansen
was probably first to combine two lenses
into compound microscope (1595)
Microscopy
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Robert Hooke (1665)
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Contemporary of
Robert Boyle
Described cork with
“cells” – first use of
“cell” to describe
structure of living
organism
Used compound
microscope
Microscopy
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Antoni van
Leeuwenhoek
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Simple single lens
microscopes
First described
bacteria, blood,
protozoa & sperm
Sent letters to Royal
Society
Microscopy
Microscopy
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Problems with early microscopes
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Chromatic aberration
Spherical aberration
Microscopy
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Chromatic
aberration
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Occurs when
different
wavelengths of light
are refracted through
the lenses at
different angles
Corrected using
glass of different
types
Microscopy
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Spherical aberration
– Distortion because light
hitting edge of lens does
not have same focal length
as middle
– Correct using small
apertures or diaphragms
– Solved by Joseph Jackson
Lister in 1830
– Why reducing diaphragm
improves contrast
Microscopy
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Microscope parts
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Ocular
Objectives
Stage
Diaphragm
Condenser
Light Source
Course adjustment
Fine adjustment
Microscopy
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Modern compound
microscope
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Diaphragm
Condenser
Oil Immersion
Microscopy
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Compound Microscope
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Total Magnification
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Refractive Index
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Ocular X Objective equals Total
A measure of the relative velocity of light
passing through a substance
Oil immersion
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prevents light scattering between slide and
objective – has same refractive index as slide
Microscopy
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Compound Microscope – Resolution
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The ability of a lens to distinguish between
two points as separate objects
Depends on wavelength of light – usually
maximum resolution is wavelength / 2
Maximum for light microscope is about 0.2
microns or about 2000x
Microscopy
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Types of Modern Microscopy
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Bright field
Dark field
Phase Contrast
Electron Microscopy
Scanning Electron Microscopy
Fluorescent (UV)
Microscopy
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Measurement (Metric System)
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Meter (m) 100
Centimeter (cm) 10-2
Millimeter (mm) 10-3
Micrometer (µm) 10-6
Nanometer (nm) 10-9
Microscopy
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Staining techniques – Preparation
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Smear
Heat Fixation
Stain/counter stain
Negative stain
Microscopy
Magnification
 Relation of Magnification to Field
Diameter
 Measuring in the Microscope
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Microscopy
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Staining Techniques – Simple stains
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Crystal violet
Saffron
Methylene blue
Mordant
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Intensifies stain
Iodine used in Gram stain
Microscopy
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Staining Techniques – Differential
Stains
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Stain one group of organisms/cells
different than another
Gram stain
Acid Fast Stain
Microscopy
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Staining Techniques – Special Stains
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Capsule
Endospore
Flagella