Chapter 3: Tools of the Laboratory/The Methods for Studying Microorganisms Flashcards
What are the key features of a reliable microscope?
Magnification & Resolving Power
What is the total magnification, and how do you find it?
A microscope’s total magnification is a combination of the eyepieces and the objective lens.
Objective lens x Ocular Power = Total Magnification
What are the 6 techniques in Microbiology?
Inoculation, Incubation, Isolation, Inspection, Info gathering, Identification
What are the main parts of a microscope and their purpose?
Ocular: to view specimen
Mechanical Stage: to move the specimen
Condenser: evenly illuminate specimen
Iris diaphragm: regulate the amount of light admitted
Built in light
Why do we need a short wavelength and a large aperture when using a microscope?
It will provide better resolution
Why are long wavelengths not ideal to use when using a microscope?
The image is too large and fuzzy that it cannot distinguish clear details
Bright Field Microscopy
most widely used; the specimen is more visible than its surroundings: used for live and preserved stained specimens
Dark Field Microscopy
brightly illuminated specimens surrounded by dark field; used for live and unstained specimens
Phase-Contrast Microscope
Used for live specimens; specimen is contrasted against gray background; excellent for internal cellular detail.
Fluorescence Microscope
Modified w/ UV radiation & filter. Useful in diagnosing infections
Scanning Confocal Microscope
Uses a laser beam to scan a specimen: focuses on multiple depths or planes (views).
Electron Microscopy
Forms an image w/ a beam of electrons
Transmission Electron Microscope (TEM)
Transmits electrons through the specimen
(Dark areas = denser, Light areas = transparent)
Scanning Electron Microscopes (SEM)
Provides a 3D view by scanning the electrons on the surface of specimen
Pure Culture
Consists of a single species of bacteria
