Download Chapter 4: Microscopy, Staining, and Classification

Chapter 4: Microscopy, Staining, and Classification
Units of Measurement
The meter is the standard unit of measurement for length. All other
measurements are fractions of a meter with bases of 10:
Decimeter- 1/10 of a meter
Centimeter- 1/100 of a meter
Millimeter- 1/1 000 of a meter
Micrometer (micron)- 1/ 1 000 000 of a meter
Nanometer- 1/ 1 000 000 000 of a meter
Microscopy
General Principles of Microscopy
-wavelength of radiation-magnification-resolution-contrastLight Microscopy- uses various types of light to examine microscopic specimens
-Bright-field microscope-Dark-field microscope-Phase microscopes-Fluorescent microscopes-Confocal MicroscopesElectron Microscopy- uses electrons to increase the resolution of specimens.
-TEM-SEM-
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Probe Microscopy- uses pointed electronic probes
-Scanning Tunneling Microscope-Atomic Force MicroscopeStaining
Preparing Specimens for Staining
Principles of Staining
-dyes used for staining are either acidic (negatively charged) or basic
(positively charged)
-staining occurs due to the bonding of the dyes to various parts of the cell
-some stains do not create chemical bonds, but accumulate in certain
parts of the cell.
Simple Stains-
Differential Stains-
-Gram Stain is the most frequently used stain in microbiology, the four
steps in the process:
1.
2.
3.
4.
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-Acid-Fast Stain is used to identify the genera Mycobacterium and
Nocardia, causes many human diseases
-cells have large amounts of waxy lipid, do not readily stain with
simple water-based dye. The steps for acid-fast staining:
1.
2.
3.
4.
-Endospore Stain is used to identify bacteria that form endospores
-Histological Stains are used mainly for tissue samples
Special Stains- simple stains designed to reveal special microbial structures
-Negative and Capsule Stain-Flagellar Stain-
Classification and Identification of Microorganisms
TaxonomyTaxaLinnaeus and Taxonomic Categories
-Linnaeus created the current system of taxonomy in 1758
-divides organisms into increasingly detailed groups:
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-uses binomial nomenclature to create a scientific name, uses the genus
and species names.
-scientific names are usually descriptive.
Domains- Proposed in 1976, three different domains:
Eukarya
Bacteria
Archaea
Taxonomic and Identifying Characteristics
-Bergey’s Manual- Two manuals that are used for identification of
prokaryotes.
-Physical Characteristics-Biochemical Tests-Serological Tests-Phage Typing-Analysis of Nucleic Acids-Taxonomic Keys-
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