Topic 1, Introduction to Microbial World.pdf

Introduction to Microbial World Murad IBRAHIM, MD PhD Department of Microbiology & Immunology Faculty of Medicine  Definitions Microbiology Microorganism Pathogen Infectious disease  Prokaryotes and Eukaryotes Universal struct...

Introduction to Microbial World Murad IBRAHIM, MD PhD Department of Microbiology & Immunology Faculty of Medicine  Definitions Microbiology Microorganism Pathogen Infectious disease  Prokaryotes and Eukaryotes Universal structures 1) Hereditary characteristics stored in DNA - Pro single chromosome - Euk linear chromosomes 2) Cell membrane (Protein and lipids) 3) Ribosome RNA protein bodies that participate in protein synthesis - Small in Pro - Free in cytosol (Pro) Prokaryotes and Eukaryotes Bacterial Cell  Bacteria Bacteria is a plural form of the latin bacterium The smallest living cells (0.1 – 10 µm)  Naming of Bacteria Binomial nomenclature Binomial nomenclature (binary nomenclature) is a formal system of naming species of living things - Two parts, both of which use Latin forms - The first part of the name identifies the genus to which the species belongs - The second part identifies the species within the genus  Naming of Bacteria Staphylococcus aureus Genus name: staphylococcus Species name: aureus S. aureus Staphylococci: group name Staphylococcus sp  Diseases caused by bacteria Diphtheria: Corynebacterium diphteriae Whooping cough pertusis: Bordetella pertusis Tetanus: Clostriium tetani Unusual examples of bacteria (Rickettsiae , chlamydiae, mycoplasma, cynobacteria)  Protozoa Single-celled eukaryotes Lack cell wall Live in the digestive tract of animal (grass and high cellulose food Grouping according to how they move One or more flagella Cilia Cytoblasmic extension (pseudopodia) Most are harmless to human (few sp are pathogenic) malaria, sleeping sickness, giardiasis, amoebic dysentery)  Fungi Eukaryotes Cell wall contains chitin (???) Yeasts e.g. Candida sp. (Oral Thrush) Molds e.g. Aspergillus sp. (Opportunistic Infections)  Viruses Neither prokaryotes nor eukaryotes Do not grow Do not display any metabolic activity Replication only within living cells Nucleic acid (DNA or RNA) Packed inside a protein shell  Viruses NA either double or single stranded Intracellular obligatory parasite Examples of viral diseases: AIDS Influenza Hepatitis Herpes infection  Viroids Viroids are infectious agents Single stranded RNA which has some double- stranded regions  Prions Prions are proteinaciuos infectious agents Cause certain “slow diseases” - Transmissible spongiform encephalopathies - Creutzfeldt Jakob disease CJD - Gertsmann Straussler Scheinker syndrome - Familial fatal insomnia in humans - Scrapie in sheep - Bovine spongiform encephalopathy Because of their simplified structures both prions and viroids are sometimes called subviral particles