Tools of the Laboratory
Microscopy
Reference: https://sites.google.com/site/rccmicrobiology/chapter-3-tools-of-the-laboratory http://dmcampus.webs.com
- Due to properties of light
- Light has a duel nature: it has properties of both a wave and a particle (photon).
- Increasing energy level and resolving power.
- Shorter the wavelength, the better the resolution.
- (READ Microscope lab, especially terms at end of chapter)
- Types
- Light Micro.
- Light Microscope Parts
- Light Source
- Condenser
- Objective lenses
- Ocular lens
- Iris diaphram
- Coarse/fine focus
- Refractive Index
- Light Microscopy
- Bright-Field (dead but cheap)
- Speciment: dark (stained)
- Background: (bright)
- Cells: dead.
- Advantages: cheap & easy. No special equipment.
- Dark Field (alive but can see outside)
- Speciment: bright.
- Background: dark.
- Cells: alive.
- Advantages: Natural shape. Good for seeing external structures, sensitive cells.
- Phase-Contrast (more expensive but can see inside.
- Speciment: Contracting areas of brightness & intensity.
- Background: Filtered light, dark.
- Cells: alive.
- Advantages: Natural shape. Good for seeing internal details.
- Fluorescence Microscopy
- Modified compound microscope (UV light)
- Cells stained with fluorescent dyes which "glow" when bombarded with UV.
- Immunofluorescent Antibody Tests (IF)
- A pathogen-specific antibody attached to IF dye.
- Rapid ID/Clinical Diagnosis
- Rabies
- Syphilis
- Anthrax
- TB
- Bright-Field Light Microscopy
- Staining
- Koch: a wet smear is made by spreading a thing film of cells on the slide.
- Microbes are dried and attatched to the slide (fixation).
- Colored, stained microbes area easier to see.
- Primary Stain: main stain of the technique. Primary stain is either kept or lost by cells.
- Counterstain: second stain used to stain cells that have lost their primary stain.
- Important terms
- Simple stain: single dye to reveal basic cell shape and arrangements: methylene blue, crystal violet.
- Negative/Positive stains: negative stain dyes the background while a positive stain dyes cell.
- Differential stain: two or more dyes to distinguish between two inds of organisms or two different parts of organisms. Gram stain, acid-fast.
- Special Stain
- Mordant
- Decoorzer: removes primary stain.
- Gram Stain (24-48 hours)
- Acid-Fast Stain M. Sp.
- Stain detect unusual, waxy, cell walls (lipid = mycolic acid)
- M. retains the pink, primary stain, Carbolfushchsin, even after washing with acid-alcohol = "acid fast."
- "Non-acid fast" cellls lose their primary stain when decoorized & counterstain blue.
- Useful for diagnosing clinical disease: TB, leprosy.
- Electron Micro
- TEM (Transmissional Electron Microscope)
- Slice, goes through.
- x10,000 to
- SEM (Scanning Electron Microscope)
- 3 demensional
- Scanning Tunneling (electron) Microscopes
- Atomic Force (AF)
- AFM uses a conducting tip (Tungsten) over the speciment surface to detect changes in charge density.
- Which microscope?
- What organism can you see with what microscope?
- Bellow nanometers, you need electron microscope.
- Resolution: ability to recognize object as being distinct.
- Dependant on light.
- Light microscope: resolutions is 0.2 mm.
Reference: https://sites.google.com/site/rccmicrobiology/chapter-3-tools-of-the-laboratory http://dmcampus.webs.com
Other lab equipments with photos & uses:
Laboratory Equipments | |
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