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transfer of microbes from their pure culture to a sterile medium without contamination of yourself, the environment, the source culture, or the medium being inoculated
safety practices for aseptic transfers
1) minimize the potential of contamination
2) be organized
3) place all media tubes in a test tube rack when not in use whether they are sterile or not
4) take your time
5) never hold a tube culture by it's cap
6) hold the inoculating loop or needle in your hand like a pencil in your dominate hand
7) adjust your bunsen burner so your flame has an inner and outer cone
generally used to grow stock cultures that can be refrigerated after incubation and maintained for several weeks
typically used for obtaining isolation of species, differential testing, and quantifying bacterial densities
colony margin may be described as:
entire (smooth with no irregularities), undulated (wavy), lobate (lobed), filamentous, or rhizoid (branched like roots)
colony elevations can be described as:
flat, raised, convex, pulvinate (very convex), and umbonate (raised in the center)
What organisms were used in the colony morphology experiment?
Why are growth characteristics more useful on agar plates than on agar slants?
the plates have a larger surface area for streaking to isolate
Why are agar slants better suited than agar plates to maintain stock cultures?
Slants are better suited because they can be capped, preventing the agar and culture from drying out. The cap also prevents airborne contaminates from entering the slant. Slants take up less storage space.
introduction of a small sample of inoculum into a container of media to produce a culture of observable growth
microbe multiplies and produces macroscopically observable growth
observation both macroscopic and microscopic appearance, biochemical tests, genetic characteristics, immunological testing
Why does a lens refract light?
the lens is optically dense compared to the surrounding medium (light travels more slowly through the lens than through air)
differences in intensity between two objects or between an object and its background - important in determining resolution
A lens refracts light waves that pass through its ___ more than light rays that pass through its ___.
What happens to light rays as they travel past the focal point?
they spread apart and produce an enlarged, inverted image
magnification of the final image is a product of the seperate magnifying powers of the objective lens and the ocular
(power of objective times power of the ocular
what is numerical aperture?
the ability of a lens to gather light from a specimen and use it to make the image
What does the condensor lens do?
directs light through the specimen as well as one or more mirrors or prisms that deflect the path of the light rays from an objective lens to the ocular lens
Simple Bright-field microscope
has a single magnifying lens, is similiar to a magnifying glass, capable of 300x magnification
Compound Bright-light microscope
has a series of lenses for magnification
light passes through specimen into objective lens
oil immersion lens increases resolution
have one or two ocular lenses
most have a condenser lens
What is the limit of useful magnification for light microscopes? Why?
2000x because their resolution is restricted by the wavelength of visible light
How do you store a microscope?
with the short objective lens in place, lower the stage, turn light intensity to minimum and turn it off, clean the lenses, wrap the cord correctly and cover
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