Chapter 10: Classification of Microorganisms Flashcards
-The science of classifying organisms
-Provides universal names for organisms
Taxonomy
-Binomial nomenclature (genus + specific epithet)
-Escherichia coli
-Homo sapiens
Scientific Nomenclature
Taxonomic Hierarchy
Domain, Kingdom, Phylum, Class, Order, Family, Genus, Species
A population of cells with similar characteristics
Prokaryotic species
Grown in laboratory media
Culture
Population of cells derived from a single cell
Clone
Genetically different cells within a clone
Strain
-Placing organisms in groups of related species
-Lists of characteristics of known organisms
Classification
-Matching characteristics of an “unknown” organism to lists of known organisms
-Clinical lab identification
Identification
Useful for identifying eukaryotes
Morphological characteristics
Gram staining, acid fast staining
Differential staining
Determines presence of bacterial enzymes
Biochemical tests
-Involves combining a known antiserum plus unknown bacterium
-Relies on antigen-antibody reactions
-Can identify species and strains within species
Serology
-A positive test produces a grainy appearance due to clumping (agglutination) of bacteria
-(Salmonella enterica – typhoid fever)
Slide agglutination test
-Enzyme-linked immunosorbent assay
-Known antibodies
-Unknown type of bacterium
-Antibodies linked to enzyme
*Color change occurs in presence of antigen-antibody complex
*Used for HIV testing (note: HIV is virus)
ELISA
-Proteins from known bacterium or virus separated by electrophoresis
-Proteins transferred to filter by blotting
-Patient’s serum washed over the filter
-If patient has antibodies toward any of the proteins they will bind
-Anti-human serum linked to an enzyme then washed over the filter
-Made visible as color band on the filter after adding enzyme substrate
Western blotting
-A test for determining which phages a bacterium is susceptible to
-A drop of each phage type is placed on the bacterial cells
-Phages that infect and lyse bacterial cells create clearings in the bacterial growth called plaques
Phage typing
-Sources of food-associated infections can be traced by _____ _____
-A patient’s infected surgical would can be traced to operating surgeon or nurses
Phage typing
Used to identify bacteria in a sample without culturing the bacteria
Flow Cytometry
-Fluid containing bacteria is forced through a small opening
-Differences in electrical conductivity between species identifies bacteria
-Fluorescence used to detect some species
-Cells selectively stained with antibody plus fluorescent dye
Flow Cytometry
-DNA fingerprinting
-DNA of two microorganisms fragmented by restriction enzymes and separated by electrophoresis producing DNA fingerprint
-“Fingerprints” compared for similarities/ differences
Genetics
-Are maps that show evolutionary relationships among organisms (clado- means branch)
-rRNA sequences are used are used since most microorganisms do not leave fossils
Cladograms
