(A) 1 bacterial classification schemes new

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(A) 1 bacterial classification schemes new

  1. 1. Topic 1 - BAcTERiAL cLASSiFicATioN ScHEMES20/09/12 1
  2. 2. Topic content Characterisation of species Binomial system Problems of classification Phylogenetic classification20/09/12 2
  3. 3. 20/09/12 3
  4. 4. Characterisation Why?..Great number and diversity of organisms. Classification: Grouping of related organism together. Many m/o look alike to be classified according to the structure Literally hundreds of bacterial species are small rods or small cocci.20/09/12 4
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  6. 6. Basic ShapesBacillus (rod-shaped)Coccus (spherical)Spiral Spirillum Vibrio Spirochete Figures 4.1a, 4.2a, 4.2d, 4.4a, 4.4b, 4.4c
  7. 7. Arrangements20/09/12 7
  8. 8. Prokaryotic Cells: ShapesAverage size: 0.2 –1.0 µm × 2 – 8 µmMost bacteria are monomorphicA few are pleomorphic Figure 4.7a
  9. 9. The Cell WallPrevents osmotic lysisMade of peptidoglycan (in bacteria) Figure 4.6
  10. 10. Gram-Positive Bacterial CellWall Figure 4.13b
  11. 11. Gram-Negative Bacterial CellWall Figure 4.13c
  12. 12. Gram-positive Gram-positive Cell WallCell WallThick peptidoglycan  Thin peptidoglycanTeichoic acids  Outer membrane  Periplasmic space Figure 4.13b–c
  13. 13. Motile CellsRotate flagella to run or tumbleMove toward or away from stimuli (taxis)Flagella proteins are H antigens (e.g., E. coli O157:H7)
  14. 14. Arrangements of BacterialFlagella Figure 4.7
  15. 15. 20/09/12 15
  16. 16. History of Binomial Nomenclature Father of taxonomy? Two name system,Latin scientific name. Formal system of naming organisms Organizing,classifying and naming organisms into groups-according to the specific criteria. How to write these names?? Vibrio cholerae Staphylococcus sp E.coli20/09/12 16
  17. 17. Genus and species Genus - capitalized species – specific epithet. Example: Escherichia coli,E.coli • Information gained: shape,who discovered,where it is found,what disease they cause.20/09/12 17
  18. 18. 20/09/12 18
  19. 19. General problems Establishing a standard names for organisms so that we can communicate about them Usually classified according to their phylogenetic or evolutionary, but not always easy Leads to introduction of a dichotomous key20/09/12 19
  20. 20. Dichotomous key Has paired statements describing characteristic of organisms Paired statement can only have one statement true Each paired statement relate to each other20/09/12 20
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  22. 22. Dichotomous Key Figure 10.8
  23. 23. Reasons causing problems 1. Deciding what constitutes a species – because of some bacteria have the similar characteristics so taxonomist try to tolerate the organism within species 2. Deciding what constitutes a kingdom – because most of organism having sexually reproduction so have very factors affecting the variable of the characteristics20/09/12 23
  24. 24. Focusing on bacterial classification Other organism categorized from domain to species, but for prokaryotic cell, start from strain to genus However facing problems reaching the classes and orders level Wide range of studies needed on identification and building up taxonomy of bacteria20/09/12 24
  25. 25. 20/09/12 25
  26. 26. Phylogenetic hierarchy Grouping organism according to common properties that implies that a group of organisms evolved from common ancestors. Each species retains some characteristics of the ancestor.20/09/12 MIC250 by Miss Rashidah Iberahim 26
  27. 27. Hierarchy domain – Bacteria kingdom – none assign for bacteria phylum – Proteobacteria class – Gamma-proteobacteria order – Enterobacteriales family – Enterobacteriacea genus – Eschericia Species – E.coli start20/09/12 27
  28. 28. Three domain system classification20/09/12 28
  29. 29. Terminologies (answer) Taxa – subdivisions used to classify organism: domain, kingdom, phylum Phylogeny / sytematic – the evolutionary history of a group of organism; phylogenetic relationships are evolutionary relationship Taxonomy – the science of the classification of organism20/09/12 m 29
  30. 30. The enD Short lecture ,but!!! MAKE MORE revision on it…. TQ20/09/12 30

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