LS 204 Microbiology Chapter 7

1. LS 204 Microbiology Chapter 7

2. Student Learning Outcomes: • 1. Name some organisms that are microorganisms • 2. Explain the importance of microorganisms to our everyday lives • 3. Describe the importance of and differences between viruses, viroids, andprions • 4. Discuss why it is important to understand the growth requirements, metabolism, and genetics of bacteria • 5. Explain how microbes cause disease and how we control them, both inside and outside of the body

3. Questions starting: • What sorts of organisms would be called microorganisms – give examples • What are some ways we benefit from microbes? • What is a virus? • How do bacteria divide? • What are some ways the human body defends itself against disease?

4. Examples of microorganisms of 3 Domains (Fig. 7.1): • Bacteria ArchaeaEukarya

5. Example microorganisms of the three Domains • Domain Archaea= prokaryotes; ‘extremophiles’; Halobacterium; Pyrococcus No human pathogens; many unusual metabolic patterns • Domain Bacteria = prokaryotes; Escherichia coli, Staphylococcus aureus; Bacillus anthracis Beneficial organisms and human pathogens; also unusual metabolic patterns • Domain Eukarya: • Kingdom Protista – pathogens like Amoeba, Trypanosoma, • Kingdom Fungi – pathogens include yeast like Candida • Kingdom Animalia – worms include Schistosoma • Kingdom Plantae – algae like Chlamydomonas

6. Importance of microorganisms • Pathogenscause disease in humans, other organisms • Beneficial organisms: • cyanobacteria and algae in oceans do photosynthesis and produce sugar and oxygen • fungi and Bacteria recycle waste products, organic molecules, oil spill • fungi and Bacteria produce food and drinks (yoghurt, beer, wine) • normal microbiota= microbes on our skin, digestive system that protect from pathogens

7. Naming microbes • Bacteria = Domain Bacteria; • bacteria = prokaryotes, includes Domain Archaea • 1 bacterium, 2 bacteria • Binomial nomenclature: Species genus • ex. Escherichia coli • Spell out genus first time it’s used, • Afterwards, can abbreviate: E. coli • Write names in italics

8. Hierarchy in Domain Bacteria • The groupings help understand shared characteristics, antibiotics that will kill them • Ex. E. coli is Domain Bacteria, Phylum Proteobacteria; Family Enterobacteriaceae • Family includes other intestinal inhabitants and pathogen genera such as Salmonella, Enterobacter, Shigella)

9. Names can reflect shapes, sizes, arrangement of cells • Coccus (cocci plural) = round • Bacillus (bacilli) = rod • Spirilla = spiral-shaped • Strepto = chains • Staphylo = clusters • Diplo- = two

10. Names can indicate properties • Escherichia coli Eponym for Dr. Escher; coli for colon • Micrococcus roseussmall red circles • Mycobacterium tuberculosis waxy cell walls, causes tuberculosis (tubercles in lungs) • Streptococcus pneumonia round cells in chains, causes pneumonia • Bacillus megateriumvery large rod-shaped organism • Thiobacillusrod-shaped organism that eats sulfur

11. More microbes: Viruses, Viroids, Prions HPV • Not considered ‘living’ since not cells, lack ability to reproduce on own (use host resources). • Virus (Fig. 7.4) has nucleic acid (DNA OR RNA) wrapped in protein coat • Some also have envelope (made of host’s membrane with viral proteins) • [Bacteriophages infect bacteria] • Animal viruses infect animals

12. Virus examples Shapes of virus capsids herpesvirus

13. Virus quantification Plaque assay – grow viruses on lawn of susceptible host cells; Infection of host cell, replication and infection of adjacent cells -> hole or plaque

14. Virus life cycle (Fig. 7.4): • Attachment: specific molecules on virus and receptors on host • Penetration: all or some of virus enters • Uncoating: protein coat removed • Biosynthesis: of viral nucleic acids and proteins • mRNA -> proteins using host ribosomes; • DNA or RNA of genome is reproduced • Release: virus breaks out of cell or buds through membrane

15. Virus life cycle (Fig. 7.4) Herpesvirus A DNA virus

16. Retrovirus life cycle (Fig. 7.4) HIV (Human immunodeficiency virus) A retrovirus: RNA genome, converts to DNA

17. Viroid : nucleic acid only – some plant diseases • Prions– only protein – animal diseases: • Spongiform encephalopathy (Mad Cow disease, elk wasting disease) Creutzfeld-Jacob disease (CJD)

18. Examples of microorganisms of 3 Domains (Fig. 7.1): • Bacteria Archaea Eukarya

19. How bacteria worktiny factories of only 1 cell compartment • Growth and nutrition: • Divide by binary fission (Fig. 7.5) – 1 cell ->2 cells -> 4 cells • Many different metabolic, nutrition patterns – more diverse than eukaryotes • Latin terms refer to metabolic patterns:

20. How bacteria worktiny factories of only 1 cell compartment • Producers include Photoautotrophs (photosynthesis, use CO2 + H2O to make sugars + O2) • Human pathogens are mostly Mesophiles (grow at middle temperatures) • Some bacteria are thermophiles (high temperatures) • Some bacteria are psychrophiles (low temperatures) cyanobacteria

21. Oxygen requirements: • obligate aerobes (skin, lungs) • Pseudomonas aeruginosa • facultative anaerobes (gut) • Escherichia coli • obligate anaerobes (puncture wound) • Clostridium tetani

22. Metabolism: similar to eukaryotes, especially for pathogens, but only 1 compartment • Catabolism to take apart molecules and gain ATP, building blocks; • Anabolism uses ATP and small molecules to build macromolecules

23. Typical metabolism: Glycolysis: 6C sugar (glucose) -> to 3-C pyruvate + ATP + NADH (e- carriers) • occurs in cytoplasm of bacteria and eukaryotes Krebs cycle (citric acid cycle): 3-C pyruvate -> CO2 + ATP + NADH + FADH2 Electron transport chain (aerobic respiration): • NADH + FADH2 + O2 -> lots of ATP + H2O + NAD + FAD • Occurs in cytoplasm of bacteria; mitochondria of eukaryotes

24. Metabolism cont. Fermentation: alternative path that does not require oxygen: occurs in cytoplasm • Pyruvate -> an organic molecule; a low energy path that recycles the NADH • Yeast make alcohol + CO2; (muscle cells lactic acid) • Bacteria make lactic acid, butyric acid, other products • (Fig. 7.6 concept map of relationships of pathways)

25. Microbial GeneticsDNA -> RNA -> protein (Fig. 7.7) • Transcriptionis DNA copied into rRNA, tRNA or mRNA • Translationis synthesis of protein from mRNA on the ribosome

26. Examples of microorganisms of 3 Domains (Fig. 7.1): • Bacteria Archaea Eukarya

27. Bacterial gene transfer Bacteria can transfer some genes from one to another (even between species) (Fig. 7.8): • Transformation = piece of DNA can go into another cell • Transduction = piece of bacterial DNA packaged in bacteriophage coat goes into other cell • Conjugation = two bacteria attach and one donates copy of some genes *** Antibiotic-resistant bacteria can transfer these genes to other bacteria

28. Bacterial gene transfermethods

29. Microbial control – how we control them. • Physical and chemical agents: • Disinfectants • Sterilants (gas, autoclave) • Sanitizers • Radiation • Chemotherapeutics (antibiotics) – compounds taken inside us to kill them

30. Principles of disease • Each pathogen has its niche – temperature, humidity, cell type, oxygen • Epidemiology – study of epidemics, or sudden large numbers of cases of disease in population. • Epidemiologists look for patterns of disease, moniter numbers • Note Latin terms, name of disease for body part: • meningitis = inflammation of meninges • bacteremia = bacteria in the blood system

31. Defenders against disease (Table 7.9) • Innate immunity (nonspecific) • First line = intact skin, mucus membranes, normal microbiota • Second line = natural killer cells phagocytic white blood cells, inflammation, fever

32. Adaptive (specific) immunity • Specialized lymphocytes: T cells and B cells • Antibodies produced by B cells circulate in blood stream • Antibodies recognize specific antigens (structures) on the pathogen • Vaccines stimulate production of ‘memory’ T cells and B cells to defend future infection