2. Virus Objectives What is a virus? What is the structure of a typical virus? How do viruses reproduce? C/C lytic and lysogenic cycles What happens to viruses once they infect an organism? * Name some viruses and what they do

3. History Iwanowski and Beijernick (1890’s) –Worked on Tobacco Mosaic Virus (infects tobacco and tomato leaves). –Creates mosaic pattern on leaves. – Made a juice of the infected leaves and then put this juice through a filter. Rubbed the filtered juice onto leaves. Still became infected. Concluded that whatever these disease causing particles were, they were very small (smaller than bacteria). Named them viruses meaning “poison”.

4. Stanley (1935) – Purified TMV into a crystal. –Living particles don’t crystallize therefore, viruses are non-living pathogenic (disease causing) particles.

5. Viruses Particles of nucleic acid, protein and sometimes a lipid envelope. Obligate intracellular parasite (can only replicate within a living cell)

6. Structure of a virus Small – 20nm (polio virus) – 350nm (small pox virus) orSingle type of nucleic acid (RNA or DNA but never both) Protein coat – capsid Some have envelopes (made of lipids)outside of capsid Surface projections made up of lipids for attachment onto host cells Are specific to their host

7. Shapes Shapes are –Rod –Helical –Icosahedral (20 sides)

8. HIV Retrovirus Envelope Projections

9. Bacteriophage Infect E. coli bacteria Attach with tail fibers onto cell. Inject nucleic acid into cell Capsid Tail

10. The Lytic Cycle Get in, replicate and get out to invade other host cells Virulent (Disease causing) The cold, rubella (German measles), mumps Release Attachment at Receptor site Entry Replication Assembly

11. The Lytic Virus infection Attaches onto host cell Injects DNA into host cell Replication of Viral parts Reassembly of virons Lysis – bursting out Viruses that reproduce only by the lytic cycle are called Virulent

12. Lysogenic Infection Virus embeds its DNA into hosts DNA which is replicated with host cell’s DNA. Remains unnoticed for sometimes years AIDS, cold sores, chicken pox, hepatitis Prophage Attachment Integration Cell multiplication & Injection of nucleic acid Prophage remains unnoticed and not transcribed

13. Lytic and Lysogenic Cycles

14. Viral Diseases Measles, Mumps, Rubella, Rabies, the Cold, the Flu, Influenza, Hepatitis, AIDS, Chicken pox, Small pox, Polio, Yellow fever, Meningititis, some cancers, Swine flu Vaccines are small doses of either killed, altered or live viruses. Body builds up antibodies against virus

15. Diseases caused by viruses AIDS The Cold Measles Mumps Rubella Chicken pox/Shingles Small Pox Hepatitis SARS The Flu Ebola HPV Bird Flu Polio

16. Polio and the Iron Lung

17. The Different forms of Viruses RetrovirusesRetroviruses – AIDS. Contains RNA instead of DNA. Goes from RNA to DNA to RNA to protein. Normal is DNA to RNA to protein. ViroidsViroids – another disease causing agent but no capsid, only the RNA. – Found only in plants PrionPrion – viral proteins that cause diseases. Scrapie in sheep degrades nervous system. Mad Cow disease (Bovine spongiform encephalopathy) in cows – puts holes into brain. – In humans, its Creutzfeld-Jakob disease & Kuru.

19. Bacterial Objectives What are the two bacterial kingdoms/domains? How are they different? Describe the structure of a typical bacterial cell and the 3 main shapes How do bacteria reproduce and metabolize? Name some common bacterial disease and their causative agents. How are bacteria important to us?

20. Formally known as Kingdom – Monera Unicellular, Prokaryotic cell (no nucleus or membrane bound organelles. Have Ribosomes and a cell wall, Single long, circular strand of DNA Auto or Heterotrophic

21. Kingdom – Archaebacteria Lack Peptidoglycan in cell wall – a sugar/protein substance Extremophiles First organisms to colonize primitive earth

22. Kingdom – Eubacteria Larger of the two kingdoms Have Peptidoglycan in cell wall 3 basic shapes –Bacilli – Rod shaped. E. coli, Bacillus anthracis

23. –Cocci – Spherical shaped. Staphylococcus aureus, Streptococcus pyogenes Strepto – Chains Tetra - 4 Staphylo –clusters Diplo – 2 Spirilla – Spiral shaped. Spirochette, Syphilis

24. Staining properties Groups Eubacteria in two groups –Gram StainingGram Staining Gram Positive – Gram stain purple with Crystal violet due to thick layer of peptidoglycan. Easier to kill with antibiotics Gram Negative – Gram stain pink with Safarin. Hard to kill with antibiotics due to thin layer of peptidoglycan

25. Basic Structure

26. Endospores Produced by Gram + (usually Bacillus & Clostridium) Dormant structure to survive adverse conditions (heat, cold, dryness). Bacillus anthracis

27. Methods of Respiration Obligate aerobic bacteria must have oxygen. –Streptococcus Obligate anaerobes die if oxygen is present. –Clostridium Facultative anaerobes w/ or w/o oxygen. –E. coli

28. Reproduction Asexually by binary fission Conjugation - Sexual repro method. Two bacteria form a conjugation bridge or tube between them. DNA is transferred from one bacteria to the other

30. Bacteria and Humans Pathogens – disease causing agents (Pathology – science of studying diseases) Can produce poisonous toxins (poisons) like the botulism toxin Destroy food crops

31. To fight them: Antibiotics interfere with cell wall or protein synthesis. Penicillin, tetracycline Bacteria can mutate and become antibiotic resistant (often results from overuse of antibiotics)

32. Helpful Bacteria: 1.Bacteria of decay - major decomposers (Saprophytes) 2.Symbiosis – Nitrogen Fixing bacteria - Convert atmospheric N2 to NH3, Rhizobium in root nodules of legumes 3.Fermentation: Food processing of sour cream, yogurt, buttermilk, wine, sauerkraut, pickles, cheese 4.Industrial – “oil eating bacteria”, mining gold, cleaning up pollutants - Bioremediation 5.Biotechnology

33. Diseases caused by bacteria Anthrax Botulism Cholera Cavities Gonorrhea Syphilis Tetanus Staph Infection (MRSA) Food Poisoning Lyme Disease Diphtheria Tuberculosis Escherichia coli O157: H7 Leprosy Meningitis Strep throat Whooping cough (Pertussis)

34. Food poisoning Results from decay of foods and production of toxins 33 million people/yr get “stomach flu” Seafood accounts for 20 – 25% of cases 33% of all raw poultry tests + for Staphylococcus 1 in every 200 eggs has Salmonella

35. 4 C’s of Food Safety Chill your foods Cook your food to the proper temperature Clean food and cooking surfaces Combat Cross Contamination

37. Antibacterial Agents Antibiotics – organic substance that inhibits growth in/on living material. Penicillin Disinfectants – inhibits growth on a non-living surface – bleach, ammonia Antiseptics– inhibits growth on a living surface – alcohol, hydrogen peroxide Sterilization – high heat or chemicals that kills bacteria

39. Antimicrobial agents DisinfectantsDisinfectants –1 – Bleach –2 – Ammonia –3 – 409 –4 – Sterile water AntisepticsAntiseptics –1 – Hand gel –2 – Iodine –3 – Alcohol –4 – Sterile water AntibioticsAntibiotics –1 – Streptomycin –2 – Erythromycin –3 – Tetracycline –4 – Sterile water BacteriaBacteria (indicate which on you have on your lab) –Bacillus cereus –E. coli –Serratia marcescens

40. Antiseptic CC Disinfectant CC Antibiotic CC