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MicroCh3Microscopy

# MicroCh3Microscopy - Chapter 3 Observing Microorganisms...

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Chapter 3: Observing Microorganisms Through a Microscope

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Microscopy: The technology of making very small things visible to the naked eye. Units of Measurement : The metric system is used to measure microorganisms. Metric system: Basic unit of length: Meter . All units are related to each other by factors of 10. Prefixes are used to indicate the relationship of a unit to the basic unit (e.g.: meter).
Metric Units of Length and U.S. Equivalents : Metric Relationship to U.S. Unit basic unit (meter) Equivalent kilometer (km) 1 km = 1000 m 1 mile = 1.61 km meter (m) 1 m = 39.37 in decimeter (dm) 1 dm = 0.1 m = 10 -1 m 1 dm = 3.94 in centimeter (cm) 1 cm = 0.01 m = 10 -2 m 2.54 cm = 1 in millimeter (mm) 1 mm = 0.001 m = 10 -3 m micrometer (um) 1 um = 0.000001 m = 10 -6 m nanometer (nm) 1 nm = 0.000000001 m = 10 -9 m picometer (pm) 1 pm = 0.000000000001 m = 10 -12 m

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Instruments of Microscopy: 1. Simple Microscopes: Only have one lens, similar to a magnifying glass. Leeuwenhoeck’s simple microscopes allowed him to magnify images from 100 to 300 X. They were so difficult to focus, he built a new one for each specimen, a total of 419. He did not share his techniques with other scientists. Even today, his source of lighting is unknown. His daughter donated 100 of his microscopes to the Royal Society shortly before his death in 1723.
Instruments of Microscopy: 2. Compound Light (CL) Microscopy History of CL Microscopes: First developed by Zaccharias Janssen, Dutch spectacle maker in 1600. Poor quality Could not see bacteria Joseph Jackson Lister (Lister’s father) developed improved compound light microscope in 1830s. Basis for modern microscopes Use visible light as a source of illumination.

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Instruments of Microscopy: 2. Compound Light Microscopy Have several lenses : 1. Light originates from an illuminator and passes through condenser lenses , which direct light onto the specimen. 2. Light then enters the objective lenses , which magnify the image. These are the closest lenses to the specimen: Scanning objective lens: 4 X Low power objective lens: 10 X High power objective lens: 40-45 X Oil immersion lens: 95-100 X 3. The image of the specimen is magnified
Instruments of Microscopy: 2. Compound Light Microscopy Total magnification : Obtained by multiplying objective lens power by ocular lens power. (Condenser lenses do not magnify image). Lens Magnification Ocular Mag. Total Mag. Scanning 4 X 10 X = 40 X Low power 10 X 10 X = 100 X High power 45 X 10 X = 450 X Oil immersion 100X 10 X = 1000 X Highest possible magnification with CL microscope is about 2000 X.

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Instruments of Microscopy: 2. Compound Light Microscopy Resolution (Resolving power): Ability of microscope to see two items as separate and discrete units. The smaller the distance between objects at which they can be distinguished as separate, the greater the resolving power.
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