Chapter 10 OVERHEADS

							                       CHAPTER 10
           CLASSIFICATION OF MICROORGANISMS

I.    The Study of Phylogenetic Relationships

      A.   Phylogeny

           1.   The evolutionary history or common ancestral relatedness
                of a group of organisms.

      B.   Taxonomy

           1.   The science of the classifications of organisms

           2.   Has basic principles, procedures and rules

      C.   Classification

           1.   Orderly arrangement of organisms into groups on the basis
                of their relationship to one another.

           2.   Taxonomic Hierarchy - Similar species are classified into a
                genus, family, order; class, phylum (or division), kingdom,
                domain.

           3.   Not right or wrong, judged on usefulness

      D.   Nomenclature

           1.    System of applying names to the groups delineated in
                classification.

           2.   Binomial- Genus - species

      E.   Identification

           1.   Allocation or assignment of an identified organism to the
                correct classification and named group.

II.   Domain System- Proposed in 1978 – Carl Woese – Three cell
      types – Two prokaryotic and one eucaryotic. Compared the
      sequences of nucleotides in ribosomal RNA (rRNA). Organisms
      differ in these as well as membrane lipids and sensitivity to
      antibiotics.
A.   Bacteria - Peptidoglycan cell wall and include all
     pathogenic and nonpathogenic prokaryotes.

B.   Archaea - Don’t have peptidoglycan, live in extreme
     environments

     1.   Methanogens – Anaerobes

     2.   Extreme halophiles – Require high salt

     3.   Hyperthermophiles – Grow in hot acidic environment

C.   Eucarya - Fungi, Plants, Animals, Protists are kingdoms in
     this domain

     1.   Fungi

          a)      Includes unicellular yeast, multicellular fungi(molds),
                  & mushrooms

          b)      Absorbs organic matter through plasma membrane

          c)      Cells in multicellular fungi joined to form hyphae

          d)      Most fungi lack flagella

          e)      Fungi develop from spores or other hyphae fragments

     2.   Plantae

          a)      Include multicellular algae, moses, ferns, conifers &
                  flowering plants

          b)      Use photosynthesis for energy

     3.   Animalia (All multicellular)

          a)      Include worms, insects, vertebrates, & sponges

          b)      Obtain nutrients and energy by ingesting organic
                  matter through a mouth.

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            4.   Protista

                 a)    Unicellular eucaryotes

                 b)    Have flagella sometime during life cycle

                 c)    Includes protozoa, fungus like water molds, slime
                       molds and primitive algae.

III.   Methods of Classifying and Identifying Bacteria

       A.   Definitions

            1.   Classification - List of characteristics and means for
                 comparison to aid in identification

                 a)    Standard Reference is Bergey’s Manual.

                 b)    Reproduce unilaterally, not breeding.

                 c)    Species is defined as population of cells with similar
                       characteristics. But sometimes a pure culture of the
                       same species contains distinguishable groups within
                       the same species. Called strains.

            2.   Identification - Figuring out what organism it is. Not
                 necessarily done with same means as classification. Done
                 for treatment etc.

       B.   Morphological Characteristics

            1.   Can do in a limited manner e.g. some bacteria look the
                 same

            2.   Differential Staining.

            3.   In clinical micro often start with what you think you have.

       C.   Biochemical Testing

            1.   The possession of various enzymes as determined by
                 biochemcial tests such as fermentation of carbohydrates.
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          a)    Dichotomous Keys – Decision Points

          b)    Probabilities such as API

          c)    Computerized

     2.   Also selective and differential media is used.

D.   Serological Methods

     1.   Microorganisms are antigenic and can stimulate antibodies.

     2.   Use antibodies in a variety of ways to either detect presence
          of microorganisms or past infections.

E.   Molecular Methods

     1.   Amino Acid Sequencing

          a)    Can tell relatedness of organisms.

          b)    Use DNA Base Composition

                (1)   % guanine+cytosine (G+C) or adenine +
                      thymine (A+T). More % is alike, more the
                      organisms are related.

     2.   DNA Fingerprinting

          a)    Actually determine entire sequence with the use of
                restriction enzymes.

     3.   PCR

          a)    Amplify DNA and then can see sequencing

     4.   DNA Probe




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