Classification microorganism first lucture

2. Classification of Microorganism
Classification : Arrangement of organisms into
groups
Taxonomy: The study and grouping of organisms
Or Organizing, classifying and naming living things
Numerical taxonomy
Phylogenetic taxonomy

3. The Three Domains

4. The Three-Domain System

5. Archaea Domain: are prokaryotic cells which are typically
characterized by membranes that are branched hydrocarbon chains
attached to glycerol by ether linkages.
Bacteria Domain: are prokaryotic cells just like Archaea, their
membranes are made of unbranched fatty acid chains attached to
glycerol by ester linkages.
Cyanobacteria and mycoplasmas are the best examples of bacteria.
Eukarya Domain: are eukaryotic cells which have membranes that
are pretty similar to that of bacteria. Eukaryote are further grouped into
Kingdom Protista (algae, protozoans), Kingdom Fungi (yeast, mold),
Kingdom Plantae (flowering plants, ferns) and Kingdom Animalia
(insects, vertebrates).
Not all Eukaryotes have a cell wall, and even if they do they don't
contain peptidoglycan as bacteria do.

6. Fungus, Fungi
 Eukaryotic
 Unicellular = yeast
 Multicellular = molds, mushrooms
 Use preformed organic matter in environment for nutrition via
hyphae
 Cell wall contains chitin
 Most beneficial in decomposition
 Some pathogenic (external and internal)
 Examples: Ringworm, Cryptococcus, Blastomycosis

7. TYPE OF FUNGI

8. Algae
 eukaryotes (cells have organelles)
 mostly photosynthetic, like plants:
Have photosynthetic pigments
Many accessory pigments – blue, red, brown, gold
Require moist environments because they lack a waxy cuticle
(remember: cuticle prevents water loss in terrestrial plants)

9. TYPE OF ALGAE

10. Protozoa
 Eukaryotic
 Unicellular
 Lack cell wall
 Classified based on movement (ciliates, flagellates, pseduopods)
 Photosynthetic or absorb/ingest/recycle nutrients from
decomposing organisms
 Pathogenic if access nutrients from living organisms
 Examples: Amoebas, Trypanosomes, Giardia, Coccidia

11. TYPE OF PROTOZOA

12. Bacteria
Prokaryotic
Unicellular
Several Shapes:
Coccus (spherical), Bacillus (Rod like), Spiral (Corkscrew)
Others are modified versions: Coccobacillus, pleomorphic
 Most beneficial, some pathogenic
 Photosynthetic or derive nutrition from environment

13. TYPE OF BACTERIA

14. Mycoplasma
Diameter=0.1-0.25 µm. They lack cell wall, are bounded by a
single triple-layered membrane.
They are the smallest organisms capable of self-reproduction.
The colony is “fried egg” appearance.
Several of them cause diseases in humans. (pneumonia,
respiratory tract disease)

15. Mycoplasma

16. Viruses
 Acellular
 Nucleic acid core of EITHER DNA or RNA (not both)
 Protein coat surrounds nucleic acid core
 + /- lipid membrane envelope
 Primary function is to reproduce/replicate, only in living tissues
 Not considered living organisms, outside host are inert
 Multiply in host cells, destroying cells in process -> tissue degradation
Other viral modifications
Virion : virus outside of the host
Viroid : RNA virus without capsid [Ebola, HIV-type 1]
Prions : protein infectious pathogens: biological activity without RNA or DNA,
possible misfolding of protein --> CNS diseases [Mad Cow, Scrapie]

17. Viruses

18. Rickettsia
 0.2-0.5µm in diameter. obligate intracellular parasites. The
majority of them are gram-negative and multiply only within host
cells.
 Binary fission within host cells.They lack the enzymatic capability
to produce sufficient amounts of ATP to support their reproduction.
They obtain the ATP from host cells.
 Many species of them cause disease in humans and
other animals.

19. Rickettsia

20. Thank You