Microbes – Bacteria, Viruses, Protists and Fungi

1. Microbes – Bacteria, Viruses, Protists and Fungi

2. Prokaryotes • Prokaryote – unicellular organism without a nucleus • DNA is found in the cytoplasm

3. Classifying Prokaryotes • 2 Kingdoms of Prokaryotes • Eubacteria • Have peptidoglycan in cell walls • Includes most of the bacteria • Archaebacteria • Live in unusually harsh environments such as hot springs, stomach acid, and salty water. • No peptidoglycan in cell walls • Cell membranes and rRNA different than Eubacteria

4. Identifying Prokaryotes • Prokaryotes can be identified based on the following: • Shapes • Cell Walls • Movement

5. Shapes • 3 Shapes • Bacilli – rod shaped • Cocci – spherical shaped • Spirochetes – spiral & corkscrew shaped

7. Cell Walls • Eubacteria can be separated based on Gram staining. • Gram Positive • Eubacteria cell walls have a thick layer of peptidoglycan that absorbs only violet dye and appears purple. • Gram Negative • Have an extra layer of lipid on the cell wall that stops the purple stain from entering and appears pink

8. Movement • Stationary • Some bacteria do not move. • Flagella (tails) • Whip like structures used for movement. • Other • Spiral shaped bacteria move in a corkscrew Motion • Myxobacteria produce a layer of slime to glide in.

9. Obtaining Energy • Autotrophs (Make their own energy) • Photoautotroph – uses the sun • Chemoautotroph – oxidize inorganic compounds as food. • Heterotrophs (Rely on other organisms for energy) • Fermentation – ferment sugars • Saprophytes – feed on dead things • Photoheterotrophs (A mix between the two) • are both autotrophic and heterotrophic • Use energy from the sun, but they require organic substances such as alcohol, fatty acids or carbohydrates.

10. Growth and Reproduction • Bacteria divide very quickly, as often as once every 20 minutes! • Binary Fission • Asexual reproduction where the bacteria divide into identical cells.

11. Endospore • Endospore – a structure produced in unfavorable conditions - A thick internal wall encloses the DNA and cytoplasm

12. Gene Transfer (Bacterial Evolution) • Mutation – random changes in DNA -passed on to daughter cells -one of the main way prokaryotes evolve • Conjugation • Bacteria make a bridge and exchange genetic material. • Transformation • Bacteria incorporate DNA from dead bacteria. • Transduction • Use viruses to transfer DNA from bacteria to other bacteria.

13. Importance of Bacteria • Decomposers • Producers • Nitrogen Fixers

14. Decomposers • Decomposers • Bacteria that break down complex molecules of dead organisms (trees, corpses) into simple molecules such as water, nitrogen compounds, and CO2

15. Producers • Producers – food chains are dependent on bacteria for producing food • 1 cyanobacterium (Prochlorococcus) is the most abundant photosynthetic organism – makes over ½ of food in the open ocean

16. Nitrogen Fixers • Nitrogen Fixers – converts nitrogen into a form plants use (N2 to NH3) • 90% of the nitrogen organisms use comes from fixation • Fix nitrogen to ammonia. • Ex: Rhizobium grows in nodules of the roots of soybeans and other legumes. It is a mutual relationship where the plant provides nutrients for bacteria and the bacteria converts nitrogen for the plant.

17. Bacteria and Disease • Pathogens • Disease causing agents. • 2 Ways Bacteria cause Disease • Damage Tissues – damage tissues of the infected organisms directly by breaking them down for food. • Ex: Tuberculosis – bacteria break down lung tissue. • Toxins – release toxins that harm the organism. • Ex: Streptococcus: causes strep throat, if untreated, the bacteria releases toxins causing a rash known as scarlett fever.

18. Bacterial Diseases

19. Human Uses of Bacteria • Food • Bacteria are used to make cheese, yogurt, buttermilk, sour cream, pickles, sauerkraut and vinegar. • Drugs (Medicines) • Also used to synthesize drugs such as insulin. • Environmental Use • Certain bacteria are used to digest petroleum after an oil spill.

20. Controlling Bacteria • Physical Removal – hand washing removes bacteria • Disinfectants - chemicals that kill bacteria • Food Storage – - refrigeration/freezing slows the growth • Food Procession – boiling, frying, steaming kills bacteria • Sterilization by Heat – kills bacteria

21. Controlling Bacteria (Cont.) • Vaccines – a preparation of weakened or killed pathogen or inactivated toxin - The vaccine stimulates the body to produce immunity to a specific disease • Antibiotics – block the growth and reproduction of bacteria • Disrupt proteins or cell processes specific to bacterial cells • Do not harm host’s cells

22. Superbugs • Use of antibiotics has lead to bacteria that are resistant to antibiotics • Penicillin killed many infections in the 1940s when it was introduced. Now is has lost effectiveness • Bacteria that are resistant to penicillin reproduce and pass resistance on through conjugation • MRSA – skin infection spread by close contact

23. Viruses

24. Viruses • Virus • Latin word for poison • Viruses are particles of nucleic acid, protein and sometimes lipids • Not alive because they are not able to reproduce independently • Reproduce by entering living cells and use the infected cell to produce more viruses

25. Structure of Viruses • Core • A core of either DNA or RNA • Capsid • A protein coat that surrounds the core • Has proteins that enable the virus to enter cells

26. Viral Infections • Viral Infection • Occur when viruses bind to specific proteins on the cell surface. Most viruses are very specific to the cells they infect. • Bacteriophages • viruses that infect bacteria

27. Lytic Cycle • Virus enters the cell • Virus destroys host DNA • Uses the host cell to make copies of itself • Host cell lyses (bursts) soon after infection releasing virus particles

28. Lysogenic Cycle • Virus imbeds its DNA into the DNA of the host cell and is replicated along with the host cell’s DNA. The cell doesn’t lyse right away. • Prophage • The viral DNA that is embedded in the host’s DNA

29. Viruses and Disease • Adenoviruses • Naked viruses w/linear DNA • Polio, measles, mumps, yellow fever, colds, and flu • Oncogenic Viruses • Disrupt normal controls on cell growth causing cancer. • Retroviruses • Usually RNA is copied from DNA, but in retroviruses DNA is copied from the viral RNA (Ex: AIDS)

30. RNA Viruses • 70% of viruses have RNA instead of DNA • RNA viruses cause colds, AIDS, cancer and others

31. The common cold The virus is brought in the host cell (nose, etc.) The host cell makes viral protein and RNA Within 8 hours the hose cell bursts and releases hundreds of new viruses

32. HIV HIV is a retrovirus – the genetic information is copied from the RNA to DNA The viral DNA remains inactive for many cell divisions When activated, the viruses damage the host’s immune system.

33. VIRUSES vs. CELLS Viruses have many characteristics of cells Viruses depend on living things and therefore were not likely to be the first living organisms.

34. New Viruses • Genetic makeup of viruses changes quickly and allows a virus to jump form one species to another. • AIDS may have jumped from nonhuman primates • “Bird flu” is a concern because it may jump to humans and is similar to some of the most deadly human versions of the flu

35. Prions • Prions • particles that contain no DNA or RNA, only proteins. • Misfolded proteins that cause other proteins to misfold. • Examples • Mad Cow Disease • Scrapies • TSE (Transgenic Spongiform Encephalitis) • The human form of mad cow. Proteins that come into contact with the prion unwind making holes in the brain so that it looks like a sponge. • How Prion's Kill

36. Protista

37. Protists • Eukaryotes that don’t fit into the plant, animal or fungi kingdoms. • Most are unicellular but can be multicellular

38. Movement • Pseudopods • Cilia • Flagella

39. Reproduction • Asexually by mitosis • Sporangium • Conjugation • Sexual Reproduction • Alternation of generations

40. Examples of Protists • Amoeba • Paramecium • Euglena

41. Ecological Significance • Parasites/Disease Causing Protists • Causes harm to host organism • Ex: Malaria • Mutualists • Lives within an organism • Both organisms benefit • Ex: Termites

42. Fungi

43. Fungi • Fungi • Heterotrophic • Feeds on other organisms • Eukaryotic • Cell Walls with Chitin

44. Structure of Fungi • Fruiting Body • Main structure of the Fungi • Reproductive structure • Mycelium • Mass of branching hyphae below the soil • Hyphae • Cells that are long, slender branching filaments • Make up both the fruiting body and the mycelium

45. Life Cycle • Spores • Asexual form of reproduction, the spores travel through air/water • Sexual Reproduction

46. Significance of Fungi • Parasites • Ex: Ringworm • Lichens • Partnership of fungi and algae • Mycorrhizae • Help feed plants