Microbiology Ch.2: How we seen the invisible world

Wavelength

• Distance between wave peaks

Amplitude

• Height of the wave

Transparency

• A large amount of light makes it through the object

Opacity

• Little or no light makes it through an object

Refraction

• The light bends around on object

Magnification

• Ability of lens to enlarge an object

Resolution

• The ability of two points to appear as two points

• How clear the image is

Brightfield microscope

• Type of microscope

• Has two lenses

- One in the eye piece with the other being the objective lens

• Total magnification found by multiplying the value on the two lenses together

Darfield microscope

• Uses a disk to block a large part of the light

• Good for unstained specimens

• High resolution and contrast

Phase-contrast microscope

• Good for unstained specimens

• High resolution and contrast

Differential interference contrast microscope

• Uses interference to enhance

• Good for living things

Fluorescence microscopes

• Uses fluorescent dyes

• Often used to tag structures of cells

- Short wavelength light is used to excite the dyes which transmit visible light

• Used a lot in clinical microbiology and in research

Confocal microscopes

• Uses laser scans to make numerous two dimensional pictures that can then be layered in to a three dimensional picture

• Sometimes uses fluorescence to increase contrast

• Good for thick specimens

Electron microscopes

• Uses electrons instead of regular light waves

• Can’t be used on living things

• Two types TEM and SEM

Transmission electron microscopy (TSM)

• Samples embedded in resin and are cut in to VERY thin slices

• Electrons are shot through a tube and travel through the specimen

Scanning electron microscopy (SEM)

• Samples are generally dried then a fixative and metal coating is sprayed

• Creates 3D look

Gram Staining Process

• Distinguishes gram positive and gram nagative bacteria

• Add small drop of water to slide

• Add specimen

• Heat fix over the burner

• Add crystal violate

• Rinse

• Add grams iodine

• Add EtOH

• Rinse

• Add safranin

• Rinse

Acid Fast Staining

• Distinguishes mycobacteria from other bacteria

Capsule staining

• Shows bacteria that have capsules and ones that don’t

• Stains the background and the cell

- The cell dye only shows on those that have a capsule

Endospore Staining

• Shows bacterial spores

Flagella staining

• Shows flagella in a bacterial sample

Eyepiece

• Part of the microscope

• Also called the “ocular lens”

• The part of the microscope that people look through

Rotating nosepiece

• Part of the microscope

• The part that holds multiple objective lenses and allows them to be rotated through

Objective lense

• Part of the microscope

• The second lens that can be adjusted by moving the nosepiece

Corse focus

• Part of the microscope

• Large nob on the side

• Moves the stage up and down in large increments

Fine focus

• Part of the microscope

• Small nob on the side

• Moves the stage up and down in small increments

Stage

• Part of the microscope

• Large platform that holds the specimen

Diaphragm

• Part of the microscope

• Shutters that exist between the stage and light

• Controls the amount of light allowed to shine through the specimen

Mechanical stage

• Part of the microscope

• Allows the specimen to move left and right

Illuminator

• Part of the microscope

• The light of the microscope