Chapter 16 Bacteria and Viruses

1. Chapter 16Bacteria and Viruses

2. Prokaryotes Or 100 Trillion Friends That You Didn’t Know You Had

3. Bacteria • Were once included in Kingdom Monera (which doesn’t exist anymore) • Now 2 separate groups: • Archeabacteria • Eubacteria

4. Archaebacteria—cell wall lacks peptidoglycan --contains membrane lipids (fats) not found in any other living things. --Live in extremely harsh environments Ex.-Oxygen-free locations (thick mud, digestive tract of animals, Great Salt Lake, hot springs, etc)

5. Biologists refer to Archeaebacteria as “extremophiles” (Lovers of the extremes) Thermophiles: Heat lovers; live in hot springs of Yellowstone National Park or deep sea ocean vents Halophiles: Salt lovers; thrive in areas like Great Salt Lake Methanogens: Oxygen free environments; such as mud at bottom of lakes and swamps where they produce “swamp gas” (methane)

6. Eubacteria—usually surrounded by a cell wall (made of peptidoglycan—a carbohydrate) that protects the cell from injury and determines its shape --As a result (of the protective cell wall), these bacteria can live almost anywhere. (fresh water, salt water, on land, on or in human body, etc)

7. E. coli, a Typical Eubacterium Pili Flagellum DNA

8. Prokaryotes are identified by: 1. SHAPE • Bacilli: rod-shaped prok’s Spirilla: Spiral and corkscrew-shaped prok’s Cocci: Spherical prok’s

9. Cell Walls • Two different kinds in Eubacteria. • Completely composed of peptidoglycan (thick) • Less peptidoglycan and an additional outer membrane (thin) • How can you tell the difference?? • Gram Staining: Test with violet and pink dyes. • Under a microscope, if the bacteria ispurplethey areGram-Positive;This is because of extra thick cell wall (lots of peptidoglycan) • If bacteria ispinkit isGram-negative.(not a lot of peptidoglycan)

10. Gram Staining Procedure

11. How is Gram Staining Useful? • Doctors use Gram staining to identify bacteria in order to prescribe the correct antibiotics. Some antibiotics only work against Gram-positive bacteria.

12. 3. Movement Some move, some don’t (non-motile) If they do move, how do they move? -flagella (might be scattered all over the cell, or in one area) -pili (short projections that help bacteria stick to each other and to surfaces) -“spiral” or “snake” forward -glide a slime like material they secrete

13. Metabolic Diversity Ways bacteria obtain energy! (modes of nutrition) Chemoheterotrophs-must take in organic molecules for both energy and supply of carbon Photoheterotroph-perform photosynthesis for energy, but must take in organic compounds as a carbon source

14. Photoautotrophs-use light energy to convert CO2 and H2O to carbon compounds and O2 Chemoautotrophs-make organic carbon molecules from CO2 (don’t require light)

15. Growth and Reproduction • Bacteria will divide very quickly if their environment is favorable • Binary Fission:Asexual reproduction - offspring are genetically identical to parent - no new genetic combinations - under ideal conditions can occur every 20 min - creates large numbers of bacteria in a short time Jeff Simmonds - The Multiplication Song http://www.youtube.com/watch?v=5Xi2Nc1UicQ

17. Each spot represents a single bacterial cell that reproduced by binary fission to produce millions of genetically identical cells. Genetically identical, good or bad?

18. Exchanging Genetic Information • Bacterial cells need to be able to exchange genetic information - creates new genetic combinations which increases the ability of the bacteria to survive • Bacteria have 3 methods for exchanging DNA -Transduction – viruses carry DNA from one bacterial cell to another -Transformation – bacteria can absorb “naked” DNA released by dead bacteria from the environment - Conjugation – two bacteria join at a conjugation bridge, one bacteria passes on a copy of its plasmid or chromosome

19. Exchanging Genetic Information

20. Transduction – DNA is carried from one bacteria to another by a virus

21. Transformation: Bacteria absorb “naked” DNA from the environment

22. Conjugation

23. Conjugation- one cell passes a copy of its plasmid or chromosome to another Recipient Cell Donor Cell A special pilus forms a connection called a conjugation bridge between 2 bacterial cells Plasmid Conjugation bridge The donor cell copies its plasmid or chromosome and passes the copy through the conjugation bridge Cells separate

24. Why are Bacteria important? • Bacteria are vital to the living world. • Some are producers that capture energy by photosynthesis. • Others are decomposers that break down the nutrients in dead matter. • Still other bacteria have human uses.

25. Human Uses of Bacteria • foods and beverages • removal of waste and poisons from water • mining minerals from the ground • synthesis of drugs and chemicals via genetic engineering • production of vitamins in human intestines

26. Viruses (Cell Pirates) • Virus: a piece of hereditary material covered by protein that infects and reproduces only inside a living organism • doesn’t grow, respond, or eat • some can be made into crystals and be dormant for years

27. Virus Structures RNA

28. Viral Infection Lytic Cycle

29. Lysogenic Infection: virus integrates its DNA into the DNA of host & viral genetic info replicates along with host cell’s DNA • Can remain inactive for long time • Prophage: viral DNA that is embedded in host’s DNA • -eventually, viral DNA will be activated & new viruses will be made

30. LysogenicCycle

31. Simply put, both types of viruses follow the same path in different time frames: • The virus attaches to the cell • The virus invades the cell • The virus makes copies of its DNA • Then the new viruses are released

33. Section 19-3Diseases caused by Bacteria and Viruses • Pathogens: disease causing agents.

34. Bacteria produce disease in one of two ways: • Damage the cells and tissues of the infected organism directly by breaking down the cells for food. • Release toxins (poisons) that travel throughout the body interfering with the normal activity of the host.

35. Bacterial Disease in Humans

36. Lyme Disease Strep Throat Bullseye mark around bite

37. How do we stop thesetypes of infections? Antibiotics – Compounds that block the growth and reproduction of bacteria; not effective against viruses.

38. There are various methods used to control bacterial growth, including: • Sterilization – Destroys all bacteria by subjecting them to great heat for a period of time. (Autoclave) • Disinfectants – Chemical solutions that kill pathogenic bacteria. (household cleaners)

39. Food Storage and Processing • Refrigerate food because the bacteria will take longer to multiply. • Boiling, frying, or steaming can sterilize certain foods.

40. Viral Disease in Humans • Viruses can attack and destroy certain cells in the body, causing symptoms of the disease. PREVENTION Vaccine – Is a preparation of weakened or killed pathogens. It works by prompting the body to produce immunity to the disease. Most vaccines work only if used before an infection begins.

41. Viral Diseases in Humans

42. Chickenpox Smallpox • Chicken pox