Chapter 17Kingdom Monera and Viruses.ppt

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1、,Chapter 17 Kingdom Monera and Viruses,I. Introduction to the BacteriaA. Symbiotic Relationships mutualism between luminescent bacteria and flash-light fish. B. Ancient Organisms known as fossils 3.5 billion years old. Fossils of eukaryotic cells are 1.5 billion years oldC. Number of Species1. About

2、 5,000 species known2. Occur in almost any natural habitat3. Some species may have many different strains (Streptomyces pneumonia has 84 strains,D. Pathogenic or Harmless? more than 90% either harmless or beneficial to humans,II. Features of the Kingdom MoneraA. Prokaryotic CellsB. Colonies or Filam

3、entsC. Motility1. Most nonmotile2. Some possess bacterial flagella3. Others move by gliding motion,D. Nutrition1. Absorption of food in solution2. Chemosynthesis i.e. obtain their energy through chemical reactions involving various compounds or elements 3. A few bacteria such as cyanobacteria and ch

4、loroxybacteria carry on a form of photosynthesis E. Reproduction1. Predominantly asexual by binary fission2. Genetic recombination in several groups through the use of pili (minute tubes that allow the passage of the bacterial chromosome from the donor cell to the recipient cell,III. Cellular Detail

5、 and ReproductionA. Cell Structure1. Prokaryotic no membrane-bound organelles2. Nucleoid single chromosome (long, very condensed DNA molecule in ring form)3. Plasmids small, circular, extrachromosomal DNA molecules,B. Reproduction1. By binary fission a bacterium may undergo fission every 10-20 minut

6、es2. Conjugation part of a chromosome is transferred from donor cell to recipient through pilus3. Transformation living cell picks up fragments of DNA released by dead cells4. Transduction fragments of DNA carried from one cell to another by viruses,IV. Size, Form, and Classification of BacteriaA. S

7、ize most are less than 2-3 m in diameter, the smallest being around 0.15 mB. Form1. Cocci spherical2. Bacilli rod-shaped or cylindrical3. Spirilli helical or spiral,C. Classification1. Based on reaction to a dye2. Two categoriesa. Gram-positiveb. Gram-negative3. Stain named after Christian Gram made

8、 observation in 1884,V. Subkingdom Archaebacteriobionta: The ArchaebacteriaA. Distinctive Characteristics1. Unique sequence of bases in RNA2. Cell walls lack muramic acid3. Production of distinctive lipids,B. The Methane Bacteria1. Anaerobic2. Produce methane from carbon dioxide and hydrogenC. The S

9、alt Bacteria1. Thrive in high salinity2. Carry on photosynthesis with the aid of bacterial rhodopsinD. The Sulpholobus Bacteria occur in sulphur hot springsE. Human Relevance of the Archaebacteria methane production for fuel,VI. Subkingdom Eubacteriobionta: The True Bacteria (Division Eubacteriophyt

10、a)A. Class EubacteriaeThe Unpigmented, Purple, and Green Sulphur Bacteria1. Heterotrophic bacteriaa. Saprobesb. Parasites,2. Autotrophic bacteriaa. Photosynthetic bacteria1) Some produce oxygen, others sulphur2) Pigments located in thylakoids bacteriochlorophyll or chlorobium chlorophyllb. Chemoauto

11、trophic bacteria1) Obtain energy through oxidation of reduced inorganic groups (NH3, H2S)2) Examples: iron, sulphur, and hydrogen bacteria,3. Human relevance of the Unpigmented, Purple, and Green Sulphur Bacteriaa. Compost and compostingb. True bacteria and disease1) Modes of access of disease bacte

12、riaa) Access from the air (“strep throat“, chlamydias)b) Access through contamination of food and drinki) Salmonella food poisoningii) Staphylococcus food poisoningiii) Legionnaires diseaseiv) Botulism,c) Access through direct contact- Syphilis and Gonorrhea, Anthrax, Brucellosisd) Access through wo

13、unds- Tetanus, Gas gangrenee) Access through bites of insects and other organismsi) Bubonic plague (the “Black Death“)ii) Tularemiaiii) Rickettsiasiv) Pleuropneumonia-like organisms (PPLOs)v) Lyme disease,2) Kochs postulatesa) Microorganism must be present in all cases of the diseaseb) Microorganism

14、 must be isolated from the victim in pure culturec) Microorganism from pure culture, when injected into susceptible host, must produce the disease in the hostd) Microorganism must be isolated from the experimentally infected host and grown in pure culture,c. True bacteria useful to humans1) Biologic

15、al controlsa) Bacillus thuringiensis (control of caterpillars)b) Bacillus thuringiensis (var. israelensis) control of mosquitoesc) Bacillus popilliae (control of Japanese beetle grubs)2) Bioremediationa) Break down of nitroglycerin and trinitrotolueneb) Pseudomonas capacia breakdown of oil spills an

16、d chemical dumps,d. Other useful bacteria1) Research into chemistry of vision2) Dairy industry3) Digestive system aids (Lactobacillus acidophilus)4) Production of metabolic wastes with industrial use5) Food production,B. Class CyanobacteriaeThe Blue-Green Bacteria1. Introductiona. Pigments1) Chlorop

17、hyll a2) Phycocyanin3) Phycoerythrinb. Can both fix nitrogen and produce oxygen2. Distributiona. Widely distributed in fresh and marine watersb. Some precipitate carbonate deposits (travertine),3. Form, metabolism, and reproductiona. Form1) Cells often occur in chains or hair-like filaments2) Some s

18、pecies occur as colonies3) Color varies depending on pigments present, although half are blue-greenb. Metabolism store carbohydrates, lipids, and the nitrogenous cyanophycinc. Reproduction1) New cells formed by fission2) New colonies may be formed by fragmentation at:a) Heterocysts (nitrogen-fixing

19、cells)b) Akinetes3) Genetic recombination,4. Blue-green bacteria, chloroplasts, and oxygena. Symbiotic origin of chloroplasts from blue-green bacteria blue-green bacteria occur symbiotically and function essentially as chloroplasts in host organismb. Speculation that chloroplasts originated as proch

20、lorobacteria5. Human relevance of the blue-green bacteriaa. Occur at bottom of food chainsb. Production of bloomsc. Poisonsd. Spirulina used as foode. Undesirable effects in human water suppliesf. Nitrogen fixation,C. Class ProchlorobacteriaeThe Prochlorobacteria1. Discovered living on sea squirts (

21、1976)2. Have chlorophylls a and b, but not phycobilins3. Thylakoid membranes double, unlike thylakoids of blue- green bacteria4. One very abundant form found at depth of 100 m in ocean waters,VII. VirusesA. Introduction1. Smallpoxa. An often fatal, communicable diseaseb. Has now been eradicated2. Va

22、ccination against smallpox performed by Edward Jenner, a country physician, in 1796,B. Size and Structure1. Vary in diameter from 15 to 300 nm2. Consist of nucleic acid core surrounded by a protein coata. Nucleic acid may be DNA or RNA, but never bothb. Protein coat often has 20 sides, resembling ti

23、ny geodesic domesC. Bacteriophages viruses that attack bacteria,D. Viral Reproduction1. Viruses replicate only at the expense of their host cells2. Viruses must become attached to a susceptible cell3. Once inside the host cell, their DNA or RNA directs the synthesis of new viral particles4. Some vir

24、uses mutate rapidly5. Viruses may affect the metabolism of their host cells6. Infected cells can produce interferon which protects uninfected cells,E. Human Relevance of Viruses1. Numerous diseases caused by viruses2. AIDS, caused by a retrovirus called HIV3. Production of vaccines4. Viroids and Prions,