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37 Cards in this Set
- Front
- Back
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Taxonomy |
- to put organisms into categories to show degrees similarities among organisms - also provides a means of identification organisms |
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Systematic or Phylogeny |
- the study of the evolutionary history of organisms |
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Eukarya |
- aminals, plants, and fungi |
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Bacteria |
- pathogenic prokaryotes, nonpathogenic prokaryotes found in soil and water - photoautotrophic prokaryotes - with peptidoglycan |
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Archae |
- includes prokaryotes that don't have peptidoglycan in their cell walls - often live in extreme environments and carry out unusual metabolic processes |
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Archae three Major Groups |
1) the methanogens, strict anaerobes the produce methane form carbon dioxide and hydrogen 2) extreme halophiles, which require high concentrations of salt 3) hyperthermophiles, which normally grow in extreme hot environments |
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Classification Scheme |
- provides a list of characteristics and a means fofr comaprison to aid in the identification of an organism |
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Identification |
- identified to determine an appropriate treatment for an infection - they are not identified by the same techniques by which they are classified |
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Bergey's Manual of Dterminative Bacteriology |
- does not classify bacteria according to evolutionary relatedness but insterad provides idenfication schemes based on criteria |
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Transport Media |
- usually not nutritive and are designed to prolong viability of a fastidious pathogens |
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Morphological Characteristics |
- helped classify organisms - tells us little about phylogenetic relationships - useful in identifying bacteria through differences of structures - ex: endospores, flagella |
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Differential Staining |
- gram negative or gram positive - acid fast staining - stains are based on the chemical composition of the cell walls - not useful in identifying either the wall less bacteria or the achear with unusual walls |
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Biochemical Tests |
- can provide insight into a species niche in the ecosystem - can differentiate amount genera - limitation: mutations and plasmid acquisition can result in strains with different characteristics |
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Rapid Identification Methods |
- manufactures for groups of medically important bacteraia - tools are designed to perform several biochemical tests simultaneously and can identify bacteria within 4 to 24 hours |
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Numerical Identification |
- the results of each test are assigned a number - test results are assigned numbers ranging 1-4 that are based on the relative reliability and importance of each test and the resulting totally in compared to a database of known organisms |
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Serology/ serological test |
- science that studies serum and immune responses that are evident in serum - involve reactions of microorganisms with specific antibodies, are useful in determining the identity of strains and species as well as relationships among organisms |
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Antiserium |
- solutions of such antibodies used in the identification of many medically important microorganisms |
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Slide Agglutination Test |
- samples of an unknown bacterium are placed in drop of saline on each of several slides - different known antiserum is added to each sample - the bacteria clump when mixed with antibodies that were produced in response to that species or strain of bacterium - positive test is indicated by the presence of clumps |
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Serological Testing |
- can differentiate not only amoung microbial species but also amount strain within species - can be used to screen bacterial isolates for possible similarities |
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Serotypes, Serovars, Biovars |
- strains with differnt antigens |
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Enzyme Linked Immunosorbent Assay |
- widely used becasue it is fast and can be read by a computer scanner - known antibodies are placed in the wells of a microplate and an unknown type of bacterium is added to each well - a reaction between the known antibodies and the bacteria provides identification of the bacteria |
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Western Blotting |
- also used to identify antigoies in a patietns serum - proteins form a known bacterium or virus are separated by an electric current in electrophoresis - the proteins are then transferred to a filter by blotting - patient's serum is washed over the filter - if the patient has antibodies to one of the proteins in the filter, the antibodies and protein will combine - anti- human serum linked an enzyme is then washed over a filter - this will be made visible as colored band on the filter after addition of the enzyme's substrate |
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Phage Typing |
- test for determing which pages a bacterium is susceptible to - starts with a plate totally covered with bacteria growing on agar - a drop of each different phage type to be used in the test is then placed on the bacteria - wherever the phage is able to infect and lyse the bacteria cells, clearings in the bacterial growth appear |
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FAME |
- comercial systems have been designed to seperate cellular fatty acids to compare them to fatty acid profiles of know organisms |
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Flow cytometry |
- can be used to identify bacteria in a sample without culturing the bacteria - a fluid containing bacteria is forced through a small opening - the simplest method detects the presence of bacteria by detecting the difference in electrical conductivity between cells and the surrounding medium - if the fluid passing through the opening is illuminated by a laser, the scattering or light provides information about the cell size, shape, density, and surface, which is analyzed by the computer |
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DNA Base Compositon |
- base compostion of single species is theoretically a fixed property - comparison of G + C content in different species can reveal the degree of species relatedness |
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DNA Fingerprinting |
- the DNA from two microorganisms is treated with the same restrction enzyme, and the restriction fragmenets produced are seperated by electrophoresis - a comparison of number, and sizes of restriction fragments that are produced from different organisms provides information about their genetic similarities and differences - used to determine the source of hospital acquired infections |
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Restiction Enzymes |
- enables researchers to campre the base sequences of different organisms - cut a molecule of DNA everywhere a specific base sequence occurs, producing a restriction fragments |
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Nucleic Acid Amplification Tests (NAAT) |
- can be used to increase the amount of microbial DNA to level that can be tested by gel electrophoresis - use PCR, reverse transcription PCR, and real time PCR |
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Nucliec Acid Hybridization |
- this procedure assumes that if two species are similar or related, a major portion of their nucleic acid sequence will also be similar - measures the ability of DNA strands from one organisms to hybridize with the DNA strands of other organisms - the greater of degree of hybridization the higher the degree of relatedness - used to detect the presence of microorganisms and to identify unknown organisms |
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Southern Blotting |
- used to identify unknown microorganisms through nucleic acid hybridization - rapid identification methods using DNA probes being developed |
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DNA Chip |
- can quickly detect a pathogen in a host or the environement by identifying a gene that is unique to a pathogen - composed of DNA probes - a sample containing DNA from an unknown organism is labeled with fluorescent dye and added to the chip - hybridization between the probe DNA and DNA in the sample is detected by fluorescence |
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Ribotyping |
- currently being used to determine the phylogenetic relationship amoung organisms - DNA can be amplified by PCR using an rRNA primer for specific signature sequences - amplified fragments are subsequently cut with one or more restriction enzymes and separated by electrophoresis - the resulting bands patterns can then be compared |
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FISH |
- floursecent dyel labled RNA or DNA probes are used to specifically stain microgoranisms in place or in situ - cells are treated so the probe enters the cell and reacts with target DNA in the cell - used to determine the identity, abundance, and relative activity of microorganism in an environment and can be used to detect bacteria that have not yet been cultured |
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Cladograms |
- maps that show evolutionary relatioships amoung organisms - each branch point is defined by a feature shared by various species on the branch |
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Steps in Constucting a Cladogram |
1) two rRNA sequences are aligned 2) the percentage similarity between the sequence is calculated 3) the horizontal branches are drawn in length proportional to the calculated percentage similarity |
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Dichotomous Keys |
- widely used in identification - identification is based on successive questions and each question has two possible answers - after answering one question, the investigator is directed to another question until an organism is determined |
