Viruses and Prokaryotes

1. Viruses and Prokaryotes Chapter 20 pages 572 - 599

2. Estimated number of viruses on the planet is 1031! If you stacked them up you would make a tower that would stretch beyond our galaxy and its neighbors. Every time you get sick with the flu the number of viruses in your body rises to 100 trillion in a few days. The slide shows viral abundance in the oceans

3. Virus – a non-living particle made primarily of proteins and nucleic acids. They can reproduce only by infecting cells. Bacteriophage –attacks bacteria Influenza virus

4. Lytic infection – viral DNA enters cell, makes copies of itself and causes the cell to burst (lyse)Lysogenic infection – viral DNA becomes part of host DNA (prophage) and may not become active for many generations

5. Shingles is a viral disease caused by the virus that causes chicken pox. After recovery from chicken pox the virus lies dormant in the cells, sometimes for years, before causing its next disease, Shingles.

7. Chicken pox – highly contagious viral disease. Causes raw pockmarks that heal. The disease is uncommon now with the advent of the vaccine.

8. Common cold is a viral disease of the upper respiratory tract. It is a retrovirus in that it contains RNA, not DNA. The host cells ribosomes translate the viral RNA into capsid and other viral proteins. Within 8 hours the host cell releases hundreds of new viruses to attack other cells.

9. HIV is a retrovirus that causes AIDS. When this virus infects a cell it makes a DNA copy of its RNA which is inserted into the host cell DNA. Like a prophage it may not activate for a while. When it does it programs the cell to produce viral proteins and RNA.

10. Helper T cells, when activated by dendritic cells stimulate B cells to produce antibodies that bind to a specific foreign protein.

11. The HIV virus attacks T4 helper cells. These are white blood cells that help acitivate other immune cells when the body is attacked by disease. • HIV infection sequence

12. Prokaryotes are either Archaea or Eubacteria. Eubacteria are the larger of the two domains.

13. Comparison of Eukarya, Eubacteria and Archaea

14. Eubacteria cell structure. Gram negative bacteria do not stain well and are more resistant to antibiotics. Gram negative bacteria Gram positive with negative

15. Archaebacteria cell structure is more similar to Eukaryotes than to Eubacteria. Archaebacteria lack peptidoglycan in their cell wall.

16. Bacteria are classified according to cell shape.

18. Bacterial colony shapes.

19. Various bacteria colony shapes and colors

20. Hallophile bacteria colonies. Pink color is the dominant trait. Needs extremely salty environment to live.

21. How organisms get energy

22. Heterotroph – Take in organic molecules from the environment or other organisms to use as both energy and carbon supply. This is a low-temperature electron micrograph of a cluster of E. coli bacteria, magnified 10,000 times. Each individual bacterium is oblong shaped

23. Photoheterotrophs – use light for energy, but cannot use CO2 as a source for carbon. Microscopic view of the bacterium Rhodobactersphaeroides, a formaldehyde-ingesting organism which can be used to clean up contaminated groundwater

24. Photoautotrophs – Use light energy to convert CO2 into carbon compounds. This is a picture of Anabena, a common filamentous cyanobacteriumthat also fixes nitrogen.

25. Chemoautotrophs – use energy released by chemical reactions involving ammonia, hydrogen sulfide, sulfur, ferrous iron and hydrogen. Bacteria living near this undersea black smoker can breakdown some of the chemicals to get energy.

26. Binary Fission – A form of asexual reproduction. Under favorable conditions bacteria can reproduce every 20 min.

27. Endospore formation – in poor conditions many bacteria can form an endospore. These spores have a tough outer coat that resists stains. The spores can exist for years and “come alive” when conditions are favorable for growth.

28. Bacterial conjugation – a hollow bridge forms between two cells and and exchange of genetic material, a plasmid, occurs. This results in a cell with a different genetic genotype.

29. Obligate aerobe bacteria. These bacteria need oxygen to survive. An example would be Mycobacterium tuberculosis: the bacterium that causes tuberculosis in human beings.

30. Tuberculosis bacteria attack the lungs. It is spread through coughing and sneezing. Most infections do not have symptoms. One in ten progress to active disease which kills 50% of those untreated.

31. Tuberculosis can cause extensive scarring in the lungs

32. Known from antiquity, there was some success in treating tuberculosis by placing people in sanatoriums, where they could get fresh air and good food.

33. Tuberculosis has been treated with a combination of drugs for over 50 years. A challenge is getting people to complete their treatment after they start feeling better.

34. Henry David Thoreau died of tuberculosis or consumption as it is sometimes called.

35. Nelson Mandela

36. Ringo Starr

37. Obligate anaerobe. These bacteria die in the presence of oxygen. they live deep in the soil, animal intestines or airtight containers. An example is Clostridium botulinum; the bacterium that causes botulism

38. A nerve toxin that the bacterium emits is what causes botulism. One of the initial symptoms is droopy eyelids.

39. Injections of botulinum toxin type A can remove wrinkles for up to 4 months.

40. Facultative anaerobe – this type of bacteria can survive without oxygen when necessary. Esherichia Coli lives anerobically in sewage and anaerobically in human intestines.

41. Bacteria are essential in the decomposition of of organic matter. In this way they return needed raw materials back into the environment. They are especially useful in the decomposition of sewage.

42. A compost pile is a way that people use bacteria to decompose organic material

43. Producers – photosynthetic bacteria are important producers. The cyanobacteriumProchlorococcusis probably the most abundant photosynthetic organism on the planet.

44. Prochlorococcus distribution.

45. Anabena – fresh water cyanobacteria – the heterocysts are cells that specialize in nitrogen fixation. Akinetes are spore-like cells that function in reproduction

46. Nitrogen fixation. Nitrogen is needed to make proteins and other molecules. Only a few prokaryotes can convert N2 into useful forms. The process involves turning N2into ammonia and the ammonia into nitrates that plants can use or attached to amino acids that all organisms can use

47. Disease causing bacteria (pathogens) cause disease by destroying living cells or by releasing chemicals that upset homeostasis. The slide below shows a person with strep throat.

48. Releasing Toxins – Some bacteria cause disease because of a particular deadly toxin they release. Diptheria is an upper respiratory illness caused by a bacterium that releases a toxin

49. Meningococcal disease – the bacteria attack the lining of the brain and the endotoxin they produce can affect the heart and rupture blood vessels.

50. A person with meningococcal disease. Even with prompt antibiotic treatment 10% of infected people die. It is not unusual for patients to lose hands and feet to this disease.