Observing Microorganisms PDF
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This document covers various aspects of microscopy and microorganisms, including techniques such as simple stains, differential stains (Gram stain, acid-fast stain), and relevant applications. It also highlights the importance of different types of microscopy and emphasizes the role of light in microscopy.
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Observing Microorganisms If a microbe measures 10 μm in length, how long is it in nanometers? Compound Light Microscopy Light Shorter wavelengths of light provide greater resolution Compound Light Microscopy The refractive index is a measure of the light-bending ability of a medium ...
Observing Microorganisms If a microbe measures 10 μm in length, how long is it in nanometers? Compound Light Microscopy Light Shorter wavelengths of light provide greater resolution Compound Light Microscopy The refractive index is a measure of the light-bending ability of a medium The light may bend in air so much that it misses the high-magnification lens Immersion oil is used to keep light from bending Light Microscopy Simple Stains Simple stain: Use of a single basic dye A mordant may be used to hold the stain or coat the specimen to enlarge it (acts like a sealant) Differential Stains Gram Stain Classifies bacteria into gram-positive or gram-negative Gram-positive bacteria tend to be killed by penicillin and detergents Gram-negative bacteria are more resistant to antibiotics Micrograph of Gram-Stained Bacteria Acid-Fast Stain Stained waxy cell wall (mycolic acids) is not decolorized by acid-alcohol (color “holds fast” in acid) Mycobacterium (M. Tuberculosis, M. leprae) Color of Color of Acid-fast Non–Acid-fast Primary stain: Red Red Carbolfuchsin Decolorizing Red Colorless agent: Acid-alcohol Counterstain: Red Blue Methylene blue Acid-Fast Bacteria