Microbiology Test #1
Microbes - ANS-small single-cell organisms not visible to the human eye, approximately
6 x 10^30
Bacteria - ANS-usually single-celled, most have cell wall with peptidoglycan, no
membrane-bound nucleus, ubiquitous and live in extreme conditions
Archaea - ANS-unique RNA gene sequences that sets them apart from bacteria, lack
peptidoglycan, unique membrane lipids, extremophiles
Viruses - ANS-smallest of microbes, requires host cell to replicate, cause range of
diseases/cancers
Viroids and Virusoids - ANS-infectious agents composed of RNA
Prions - ANS-infectious proteins
Microbial Fossils - ANS-evidence of first life, believe that earliest molecules were RNA,
has some catalylic ability --> ability to help peptide bonds form
Earliest Metabolism - ANS-existed in reducing environment (organisms lose electrons to
metabolize), contrasts with current oxidizing environment (electronegative oxygen
accepts electrons)
Horizontal Gene Transfer - ANS-helps Bacteria and Archaea develop genetic diversity
-primary mechanism by which antibiotics transfer
they do not reproduce sexually (use binary fission), so instead of calling them a species
we call them a strain
Microscopes - ANS-focus light rays at a specific place called the focal point
-Focal length: distance between center of lens and focal point is the
-Resolution: ability of a lens to distinguish small objects that are close together, shorter
wavelength of light = greater resolution
-Working distance: distance between front surface of lens and surface of cover glass
, Dark Field Micoscopes - ANS-use a black background
-can observe treponema pallidum, the causative agent of syphilis
Staining Specimen - ANS-1. increases visibility of specimen
2. accentuates morphological features
3. preserves specimens
-fixation: kills organism and attaches it to slide
-dyes: make internal/external structures more visible
Types of Stains - ANS-Differential: distinguish group of microorganism
Simple: determine size, shape, and arrangement of bacteria
Acid-Fast Stain: stains the genus mycobacterium
Endospore Staining: heated, double-staining technique that identifies endospore
Gram staining: determines negative (no peptidoglycan) and positive (thick
peptidoglycan)
Koch's Postulates - ANS-1. microorganism must be present in every case of the disease
but absent from healthy organisms
2. suspected microorganisms must be isolated and grown in a pure culture
3. same disease must result when the isolated microorganism is inoculated into a
healthy host
4. same microorganisms must be isolated again from the diseased host
Electron Microscopy - ANS-electrons replace light as the "illuminating" beam, able to
study morphology
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