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Micro organisms


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Micro organisms

  1. 1. 201119946 MOSELANE T.T
  3. 3. What is Microbiology? Microbes, or microorganisms are minute living things that are usually unable to be viewed with the naked eye. What are some examples of microbes? Bacteria, fungi, protozoa, algae, viruses are examples! Some are pathogenic Many are beneficial Dr.T.V.Rao MD 3
  4. 4. ………………continues  Study of different Microorganisms  Can be Bacteria Viruses Parasites Fungus 4
  6. 6. Dutchman anton van leeuwenhoek observed microorganisms>>”animalcules” suspended in a drop of pond water in front of a ground hand lens 6
  7. 7. History; contd.  ROBERT HOOKE built simple compound microscope and observed structure of thin layer of cork>>used the word “CELLS”  Theory of spontaneous generation: from non-living matter  Theory of biogenesis: from preexisting living cells  LOUIS PASTEUR>>Pasteur’ experiment>>boiled nutrient broth in a flask & curved it in to S-shape>>after cooling>>bacteria trapped in curve but no organism in flask; dicovered souring in alcohol is due to fermentation and can be prevented by heating wine at56oC for 30mins… called PASTEURISATION>> 7
  8. 8. History contd;  IGNAZ SEMMELWEIS was concerned at high incidence of puerperal fever and latter instituted hand washing in chlorinated solutions; ridiculed by colleagues and was dismissed; died of STREPTOCOCCAL INFECTION  JOHN SNOW: transmission of cholera due to contamination of the river Thames….later confirmed by ROBERT KOCH in German 8
  9. 9.  Bacteriology is the study of bacteria.  Mycology is the study of fungi.  Parasitology is the study of protozoa and parasitic worms.  Recent advances in genomics, the study of an organism’s genes, have provided new tools for classifying microorganisms.  Proteomics is looking at the gene products Definitions 3/10/2014Dr.T.V.Rao MD 9
  10. 10. Classification of micro-organisms  All living organisms are classified into: Kingdom Phylum (family) Genus Species  Organisms that can cause disease are many and varied and include: Viruses Bacteria Fungi Parasites 3/10/2014Dr.T.V.Rao MD 10
  11. 11.  Different: Diseases Modes of transmission Treatment-e.g. routinely use antibiotics don’t cure vira lfungalinfections Relevance of Classification 3/10/2014Dr.T.V.Rao MD 11
  12. 12. Microorganisms Non-cellular organism Prokaryotes Eukaryotes Others Prions Viroid Fungi Bacterium Virus Dr.T.V.Rao MD 12
  13. 13. Prokaryotic cells Eukaryote cells Small cell (< 5µm) Larger cells (> 10 µm) Always unicellular Often multicellular No nucleus or any membrane bound organelles Always have nucleus and membranes bound organelles. DNA circular, without proteins DNA is linear and associated with proteins to form chromatin. Ribosomes are small 70S Ribosomes are large 80S No cytoskeleton Always have cytoskeleton Motility by rigid rotating flagellum made from flagellin Motility by flexible waving cilia or flagella made from tubulins. Cell division is by binary fission Cell division is by meiosis and mitosis. Reproduction is always asexual Reproduction is sexual and asexual. Summary of differences between prokaryote and eukaryote cells
  14. 14. Prokaryotic Cell Structure • Prokaryotic cells are about 10 times smaller than eukaryotic cells. • prokaryotes are very simple cells when compared with eukaryotic cells, • Reproduction of prokaryotic cells is by binary fission, the simple division of one cell into two cells.
  15. 15. Bacteria  Prokaryotes  Peptidoglycan cell walls  Binary fission  For energy, use organic chemicals, inorganic chemicals, or photosynthesisDr.T.V.Rao MD 15
  16. 16. Bacterial Cell Wall structure
  17. 17. Morphologic arrangements of bacteria.
  18. 18. Capsule stain. The capsule stain is an example of a negative staining technique. The bacterial cells and the background stain, but the capsules do not. The capsules are seen as unstained “halos” around the bacterial cells.
  19. 19. Binary fission. Note that DNA replication must occur before the actual splitting (fission) of the parent cell.
  20. 20. Pathogenic Prokaryotes Mycoplasma Bacteria Spirochetes Rickettsia Chlamydiae Actinomyces Dr.T.V.Rao MD 20
  21. 21. Viruses Viruses lack many of the attributes of cells, including the ability to replicate. Only when it infects a cell does a virus acquire the key attribute of a living system: reproduction A viral particle consists of a nucleic acid molecule, either DNA or RNA, enclosed in a protein coat, or capsid Viruses are known to infect all cells, including microbial cells. Host-virus interactions tend to be highly specific Dr.T.V.Rao MD 21
  22. 22. Discovery of Virus  Iwanovski  a Russian chemist, 1892  Tobacco Mosaic Disease  Beijerinck confirmed  Walter Reed, USA  Yellow fever virus  Ist human virus Tobacco mosaic disease, caused by the tobacco mosaic virus Dr.T.V.Rao MD 22
  23. 23. Viruses  A virus is not a cell!  Viruses are replicated only when they are in a living host cell  Consist of DNA or RNA core  Core is surrounded by a protein coat  Coat may be enclosed in a lipid envelope Dr.T.V.Rao MD 23
  24. 24. What are Viruses  Viruses Dependent on Host cells for necessary functions and Multiplication Intracellular parasites Contain either DNA or RNA never both. Dr.T.V.Rao MD 24
  25. 25. Fungi  Complex, large organisms  Eukaryotes (as are humans!)  Divided into yeasts & moulds  Cause a range of diseases e.g.:  Thrush  Athletes foot  Invasive & allergic aspergillosis  Many diseases are opportunistic. 3/10/2014Dr.T.V.Rao MD 25
  26. 26. Protozoa Eukaryotes Absorb or ingest organic chemicals May be motile via pseudopods, cilia, or flagella Figure 1.1c 3/10/2014Dr.T.V.Rao MD 26
  27. 27. Multicellular Animal Parasites  Eukaryote  Multicellular animals  Parasitic flatworms and round worms are called Helminths.  Microscopic stages in life cycles. Figure 12.28a 3/10/2014Dr.T.V.Rao MD 27
  28. 28. Disease-causing microorganisms are called pathogens.  Pathogenic microorganisms have special properties that allow them to invade the human body or produce toxins.  When a microorganism overcomes the body’s defenses, a state of disease results. Diseases and Infections 3/10/2014Dr.T.V.Rao MD 28
  29. 29. Pathology, Infection, and Disease  Pathology is the scientific study of disease.  Pathology is concerned with the  etiology (cause),  pathogenesis (development),  effects of disease – structural and functional changes brought about by disease.  Infection is the invasion and growth of pathogens in the body.  A host is an organism that shelters and supports the growth of pathogens.  Disease is an abnormal state in which part or all of the body is not properly adjusted or is incapable of performing normal functions.  Infection disease – presence of particular microorganism in part of the body where is not usually found. 3/10/2014Dr.T.V.Rao MD 29
  30. 30. Classifying Infectious Diseases  Communicable diseases are transmitted directly or indirectly from one host to another. Chicken pox, genital herpes, A contagious disease is one that is easily spread from one person to another.  Noncommunicable diseases are caused by microorganisms that normally grow outside the human body and are not transmitted from one host to another Tetanus, Clostridium tetani 3/10/2014Dr.T.V.Rao MD 30
  31. 31.  Recombinant DNA Technology  Genes in microbes, plants, and animals manipulated for practical applications  Production of human blood- clotting factor by E. coli to aid hemophiliacs  Gene Therapy  Inserting a missing gene or repairing a defective one in humans by inserting desired gene into host cells The Modern Age of Microbiology 3/10/2014Dr.T.V.Rao MD 31
  32. 32. Discovery of Antimicrobial Agents _________  Alexander Fleming (1881 – 1955), a Scottish biologist and pharmacologist, observed bacterial staphylococci colonies disappearing on plates contaminated with mold.  Fleming extracted the compound from the mold responsible for destruction of the bacterial colonies.  The product of the mold was named penicillin, after the Penicillium mold from which it was derived.  Nobel Prize in Physiology of Medicine in 1945. Images: Penicillium mold, PHIL #8396; Staphylococcus aureus on antibiotic test plate, PHIL #2641; Poster attached to a mailbox offering advice to World War II servicemen, 1944, NIHFrom the Virtual Microbiology Classroom on 3/10/2014 Dr.T.V.Rao MD 32
  33. 33. The Modern Age of Microbiology  How Do We Defend Against Disease?  Serology The study of blood serum Von Behring and Kitasato – existence in the blood of chemicals and cells that fight infection  Immunology The study of the body’s defense against specific pathogens  Chemotherapy Fleming discovered penicillin Domagk discovered sulfa drugs 3/10/2014Dr.T.V.Rao MD 33
  34. 34. REFERENCES  Picture on slide no: 1 taken from illustration-of-microbiology-science--microorganisms.html  Picture on slide no: 15 taken from; aryote_cell-_en.svg/494px-Average_prokaryote_cell-_en.svg.png  HISTORY OF MICRO ORGANISMS AND PICTURES, DR PRABESH K CHOUDHARY microbiology-introduction/ 2001
  35. 35.  Definition of terms; Dr.T.V.Rao MD, microbiology-medical-graduates/ , 2014  Notes on classification and pictures, DR PRABESH K CHOUDHARY microbiology-introduction/  Microbes diseases and pictures, R Saravanan, introduction-of-microbiology-saravanan/ , 2010  NOTES BACTRIA AND VIRUS and pictures, vidhyakalai microbiology-vidyakalaivani/ 2000