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  1. 1. 1
  2. 2. A Seminar on MICROBIOLOGY by Mr. Ramavatar Sharma (Reg. no. 10-104-2012) to Prof. P.D. Chavda College of RE & EE 2
  3. 3. MICROBIOLOGY  Microbiology is the study of microorganisms, which are unicellular or cell-cluster microscopic organisms. This includes eukaryotes such as fungi and protists, and prokaryotes. Viruses, though not strictly classed as living organisms, are also studied. Micro-organism  Microorganisms are very tiny one-celled organisms, viruses, fungi, and bacteria, and are found everywhere in the world. They are found in all living things, plants and animal.  There are more microorganisms on and inside your body than there are cells that make up your entire body. Microorganisms can live in the air, on land, and in fresh or salt water environments. Some of them, pathogens, can be harmful and causes diseases, but there are some microorganisms that are needed for living things to survive. 3
  4. 4. Characteristics of viruses  Virus is a Latin Word Which Means Poison and Toxin.  Kunkle in 1947 in distinguishing virus diseases from fungal diseases came to the conclusion that viruses are most efficient pathogen.  Viruses get themselves into the cells by the finest and most efficient hypodermic syringes known to man, that is the proboscis of insects.  Viruses escape quarantine screening very simply in masked carries hosts.  When the plant being attacked becomes immune, they mutate to produce a more virulent strain that can successfully invade the plant.  Viruses are invisible, non microscopic except with electron microscope. 4
  5. 5.  Bowden in 1964 describes viruses as ”submicroscopic” , infective entities that multiply only intracellularly and are potentially pathogenic.  He associated viruses with three characteristics (i) Invisibility (ii) Pathogenicity (iii) Ability to multiply only intracellularly  Because some viruses could pass through becterial filters, they are described as filterable virus.  They are host specific i.e. each type of virus can infect and parasitise only a limited range of host cells called host ranges. 5
  6. 6.  They identity their specific host by a lock and key system i.e. fit between proteins and the outside of the virus specified receptor molecules on the surface of cells.  Some virus can infect a broad host range e.g. the rabies virus can infect rodents, dogs and humans.  Viruses that parasitise bacteria e.g. Escherichia coli are called phages.  The phages parasitize only the bacterium E.coli. The influenza virus only infect the lining of human upper respiratory tract ignoring other tissues.  The AIDS virus binds to specific receptor on certain type of white blood cells passes through bacterial filters. 6
  7. 7.  Chester in 1974 is described viruses as one of the most interesting, mysterious and elusive plant pathogens. They are contagious, transmissible and are capable of causing some of the most destructive diseases not only on plants but also on animals and man.  Virus are non-motile but are carried by insects vectors.  Viruses lack metabolic capabilities possessed by bacteria and fungi but depend on their hosts not only for substances but also for the mechanism that synthesise their substances. 7
  8. 8. Virus shapes  Tobacco mosaic virus has a helical capsid with overall shape of a rigid rod. 8
  9. 9.  Adenovirus has a polyhedral capsid with a protein spike at each vertex. Some adenoviruses cause respiratory infections in humans. 9
  10. 10.  Influenza virus has an outer viral envelope studded with glycoprotein spikes. 10
  11. 11.  A phage (bacterial virus). 11
  12. 12. Viruses can either be living or non-living They are Living particles because they have the ability to:  Multiply within appropriate cell, a process resembling reproduction  To undergo mutation. They are non-living particles because they have no:     Metabolic system Intrinsic motility Ability to respond to stimuli Can not be cultured outside the host cell i.e. they are obligate parasite. They live in the host cells intracellularly. 12
  13. 13. Deleterious effects of viruses  Man is effected by many virus diseases, e.g. smallpox, common cold, epidemic influenza, mumps, measles, poliomyelitis, rabies etc.  Animal are also affected by viruses e.g. foot and mouth disease of cattle, sheep and goats. Cattle plague, rabies of cats, dogs, sheep and goats, newcastle disease of pigeons, ducks, turkeys, fowl-pox, cow pox and psittacosis of birds. 13
  14. 14. Domesticated honey bees are affected by fowl brood and caterpillar wilt, fishes are said to have virus also and even bacteria are affected by virus. As cited by Bowden in 1964, Gandy and Hollings in 1962 reported the die-back of mushrooms. Viruses have no protein synthesing apparatus for manufacturing of ribosome, transfer RNA, mRNA. A virus therefore depends on its host cell for its energy and for translating its genomes into proteins, t-RNA, mRNA a and r-RNA e.g. they infect bacteria cells to give rise to what is known as a bacteriophage e.g. Escherichia coil and T2 even phage. 14
  15. 15. Comparison of viruses with other micro-organisms A virus particle is not a micro-organism because:  An organism consists of one or more cells that operate by following the instruction of their genomes. A virus on the other hand is an independent genome enclosed in a protective covering that allows it to survive outside the host cell and to invade functioning cells which becomes its host.  The virus takes the form of a particle called virion each of which consists of a nucleic acid genome encloses in a capsid. The virion contain only one kind nucleic acid ether DNA or RNA. 15
  16. 16. Viruses reproduce solely by using the information in the one nucleic acid while the organisms including parasites reproduce through integrated actions of all there constituents. Viral genomes do not contain an apparatus for generating energy. Viruses do not grow as cells do by enlarging and dividing nor do they reproduces as organisms do. Either asexually or sexually. Instead virus infected cells synthesise new virions in much the same way a factory manufactures products. 16
  17. 17. Transitory and persistent viruses  Viruses can be transitory if:  It does not persist in its vector i.e. the infectivity decreases with time  It has a short retention period  It lacks a demonstrable latent period in the vector  Infectivity is lost after the insect molts. 17
  18. 18. Viruses can be non-transitory if:  It persists in its vector.  It has a long retention period.  It has latent period vector.  It does not loose infectivity after insect molting. 18
  19. 19. Characteristics of bacteria  Bacteria are prokaryotic unicellular organisms.  Bacteria are larger organisms then virus ranging from 0.5-1.5um in diameter they can be seen with the aid of alight microscope i.e. they are microscopic.  They are either gram negative or gram positive .  They have all the characteristics common to other organisms . they are cellular, posses comparable metabolism and are microscopic specially with the oil immersion (x 100) objective . 19
  20. 20.  Some bacteria cells are flagellated. The flagella vary from one to many which may be positioned on any part of the bacterial cell. The location of the flagella could be group characteristics.  Bacteria are micro-organisms without a true nucleus or plastics and packing any sexual reproduction process .  Bacteria reproduces asexually by binary fission .  Bacteria are saprophytes , parasites or autotrophs.  Bacteria can be cocci, rod-like, spiral. Bacteria can also be single cells or in chains.  Some Bactria are naked i.e. without cell wall. 20
  21. 21. CHARACTERISTICS OF FUNGI  Fungi are plants with thread like non-photosynthetic threads called hypha. These were initially classified among the Thallophyta (Lowson,1962) a class under the non-flowering, non-seed producing but spore bearing plants. However by 1969, the fungi was raised to the level of a kingdom (Campbell, 1996). The non-photosynthetic thread (hyphae) are either septate with cross-walls (non-coenocytic) or without crosswalls (coenocytic) 21
  22. 22.  A collection of these hyphae are referred to as mycelium. Fungal hyphae are bounded by a cell wall made up of glucans and chitin. The eukaryote contains a nucleus with a nuclear membrane enclosing the chromosomes. Also present are mitochondria and endoplasmic reticulum. These characteristics differentiate fungi from bacteria. 22
  23. 23.  The fungal kingdom is divided into two division. The Myxomycota (false fungi) and the Eucomycota (true fungi).  The Eucomycota is divided into five sub-divisions based on their reproductive structures.  These are Hemiascomycota, Mastigomycota, Zygomycota, Ascomycota, Basidiomycota and Deuteromycota. These five sub-divisions vary from being unicellular as in saccharomyces to multicellular as in the advanced fungi e.g. Ascomycota, Basidiomycota and Deuteromycota these are fungi with the septate hyphae and heterothallic method of reproduction. The primitive fungi are the coenocytic non-septate fungi including the Mastigomycota and Zygomycota. 23
  24. 24. 24
  25. 25.  They are chlorophyll less, eukaryotic unicellular or multicellular plant.  They are heterotrophs, acquiring their nutrients by absorption , consisting of sabrobic decomposers, parasitic species and mutualistic forms  The body or vegetative structure of a fungus is called a thallus varying in complexity and size ranging from the unicellular yeast to multicellular molds.  They reproduce asexually by dispersing different types of spores and sexual reproduction can be homothallic, heterothallic or by conjugation. 25
  26. 26.  They have a tremendous ecological impact as molds, yeasts, lichens, saprophytes mycorrhizas and parasites.  Without fungi and bacteria as decomposers, biological communities would be deprived of the essential recycling of chemical elements.  They are impotent decomposer of wood, food and other useful objects.  Cause diseases in plants (parasitic) and animals (dermatophytic). 26
  27. 27. Characteristics of algae  Algae were formally member of the class thallophyta of the old plant kingdom.  They are of various colors ranging from green, blue-green, red, brown or golden.  They are the eukaryotic-with distinct nucleus.  They could be heterrotropsh, photoautotrophic except the prokaryotic cyanobacteria(blue-green algae in a symbiotic reltions).  Some are flagellated while other are not. 27
  28. 28.  They are aquatic either fresh water or as marine phytoplankton.  Algae from the bases of aquatic food webs that support enormous abundance and diversity of life.  All algae posses’ chlophyll, the primary pigments that trap wavelength of length to which chlorophyll is not as sensitive.  The mixture of pigments chloroplasts lend characteristic color related to these algae. 28
  29. 29.  Algae from the bases of aquatic food webs that support enormous abundance and diversity of life.  All algae posses’ chlophyll, the primary pigments that trap wavelength of length to which chlorophyll is not as sensitive.  The mixture of pigments chloroplasts lend characteristic color related to these algae.  They are filamentous, thread like, photosynthetic plants ranging from unicellular as in Chlamydomonas sp. 29
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