millimeter (mm)
10^-3
micrometer (um)
10^-6
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Brainpower
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nanometer
10^-9
Microbes
Organisms and acellular agents too small to be seen by the unaided eye
...
millimeter (mm) - ANSWER-10^-3
micrometer (um) - ANSWER-10^-6
nanometer - ANSWER-10^-9
Microbes - ANSWER-Organisms and acellular agents too small to be seen by the
unaided eye
Robert Hooke - ANSWER-made first compound microscope, coined the term "cell"
Antoine van Leeuwenhoek - ANSWER-built single-lens magnifier, first to observe
single-felled microbes
Francesco Redi - ANSWER-meat and maggots research, disproved theory that
microbes spontaneously generated
Lazzaro Spallanzani - ANSWER-also disproved the spontaneous generation theory,
used broth covered and uncovered
Louis Pasteur - ANSWER-proposed the germ theory of disease, idea that the
transmission of microbes is what causes disease, also used Swan neck flasks and broth
to disprove spontaneous generation
germ theory of disease - ANSWER-idea that infectious diseases are caused by
microorganisms, important features: transmission, pure culture, colonies
Robert Koch - ANSWER-Father of microbiology, four postulates to establish link
between specific microbe and a disease
Koch's first postulate - ANSWER-Microorganism must be present in every case of the
disease and absent from healthy organisms
Koch's Second Postulate - ANSWER-Microbe must be isolated and grown in pure
culture
Koch's Third Postulate - ANSWER-Same disease must result when organism is
inoculated in healthy host
Koch's Fourth Postulate - ANSWER-Same microorganism must be isolated from 2nd
diseases host
Limitations of Koch's Postulates - ANSWER-Some have immunity, some illnesses have
multiple causes/strains, and, since you can't inoculate humans, a disease that only
affects humans would be difficult to test
Lady Montagu - ANSWER-Introduces smallpox inoculation in 1717
Edward Jenner - ANSWER-Smallpox vaccine (furthers Lady Montagu's work)
, Florence Nightingale - ANSWER-Used medical statistics to demonstrate the
significance of mortality due to disease during the Crimean War
Alexander Fleming - ANSWER-discovered penicillin
Howard Florey and Ernst Chain - ANSWER-Purified penicillin
Sergei Winogradsky - ANSWER-Discovered lithotrophs, developed enrichment cultures,
and built the Winogradsky column
Detection - ANSWER-The ability to determine the presence of an object
Magnification - ANSWER-An increase in the apparent size of an image to resolve
smaller separations between objects
compound microscope - ANSWER-A light microscope that has more than one lens
bright-field microscopy - ANSWER-Ocular lens (10x), condenser, objective lens, total
magnification is equal to the product of the ocular lens magnification times the objective
lens, can see microbes but can't tell much about sample
Limitations of bright-field microscopy - ANSWER-0.2 um between objects is best a
bright-field microscope can resolve
dark-field microscopy - ANSWER-Microbes visualized as halos of bright light against
darkness
phase-contrast microscopy - ANSWER-Allows refractive differences in cell components
to be transformed into differences in light intensity (allows you to see internal
components)
Fluorescence microscopy - ANSWER-For specimens with added dye or naturally
photosynthetic microbes
Fluorophores - ANSWER-Chemical compounds that absorb/emit light of specific
wavelengths; can be a dye or protein
basic dyes - ANSWER-Positively charged
- examples: methylene blue, crystal violet, and safranin
- often used in the surface of a cell
acidic dyes - ANSWER-Negatively charged
- examples: eosin, rose bengal
- used on positively charged samples
Differential staining - ANSWER-gram staining, acid-fast staining, endosphere staining
Gram staining - ANSWER-Has to do with cell wall properties
Peptidoglycan - ANSWER-Rigid structure that lies just outside the plasma membrane
Gram stain procedure - ANSWER-1. Add crystal violet after fixation (colorless)
2. Both are purple
3. Add iodine (traps crystal violet); still purple
4. Add alcohol (decolorizing step); crystal violet only lost in gram -
5. Add counterstain, safranin
(Gram + will be purple, Gram - will be red)
electron microscopy - ANSWER-Electrons used instead of light beam (shorter
wavelength means greater resolution)
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