classification of organisms

classification of organisms

1. taxonomy

   • - arrange into groups based on mutual characteristics.
   • i. classification
     • - arrangement of organisms into groups or taxon based on mutual similarities
   • ii. identification
     • - process of dicovering the traits of organisms
   • iii. nomenclature
     • - assigning names to the taxonomic groups
     • Genus name + species
       • - genus name must be uppercase - species name should be lowercase
     • both must be underlined
       • eg: Thiomargarita Namibiensis
     • general rules :
       • 1. genus name capitalized , species name shouldn't 2. genus name can stand alone without species name. 3. species name must follow after the genus name. 4. both name must be underlined. 5. spell the full name for the first time but can make the genus name short for the second time and below.

2. strain

   • subgroup of species with 1 or more characteristics that is different from the other subgroup in the same species.
   • identify by :
     • i. name ii. number iii. letter follows by specific epither
   • ways to describe strains in the same species:
     • i. biovars
       • characterized by biochemical or physical differences
     • ii. morphovars
       • morphologically different
     • iii. serovars
       • different antigenic properties
   • inspiration of names :
     • shape place it was found nutrient it used the person who discovered diseases it caused

3. methods of classifying and identifying microorganisms

   • i. morphological characteristics
     • - cell type - shape and size - grouping - external structure - internal structure
   • ii. differential staining
     • gram stain
       • gram (+) -purple/blue gram (-) -pink/red
     • acid-fast stain
       • stain bacteria with waxy material in their cell wall
     • negative staining
       • use india ink to create contrasting colour with the background
     • endospore staining
       • endospore appear green within pink cells
     • flagella staining
       • use mordant and stain carbolfuchsin to coat the thin flagella to look thicker.
   • iii. biochemical test
     • to verify metabolic activity
     • common biochemical test:
       • 1. phenol red broth 2. gelatin test 3. lipase test 4. starch hydrolysis 5. motility test 6. catalase test
   • iv. serology
     • study serum and immune response evident in serum.
     • 1. bacteria enter the host 2. host produce antibody 3. antibody combine with antigen 4. produce precipitate
     • serological techniques:
       • Enzyme-linked immunosorbent assay
         • (ELISA) - fast - use computer to read results
       • western blotting
   • v. phage typing
     • bacteriophage cause lysis of bacteria that they infect
     • bacteriophages infect specific species
   • vi. fatty acids profile
     • to classify and identify the unknown
   • vii. DNA fingerprinting
     • use restriction enzyme to produce banding patterns
       • the more similar the DNA fingerprints, the more closely related the organisms are
   • viii. DNA base composition
     • expressed as the % og Guanine + Cytosine
       • to reveal the degree of species relatedness
   • nucleic acid hybridization
     • - to determine extent of similarity based on degree of reunion. - to measure the ability of DNA strands from 1 organism to hybridize with another
     • techniques :
       • i. southern blotting
         • - use DNA probe (short specific unit of DNA strands)
       • ii. ribotyping and ribosomal RNA sequencing
         • - targets on rRNA
       • DNA chips
         • - DNA from unknown organism is labelled with fluorescent dye , so the hybridization of probe and unknown DNA is detected by fluorescent.
       • iv. Fluorescent In Situ Hybridization
         • - highly sensitive - do not require lots of cells