Bacteria and Archaea

1. Evolutionary History of Biodiversity Bacteria and Archaea

2. Three Domains of Life

3. Fig. 26-21 EUKARYA Dinoflagellates Land plants Forams Green algae Ciliates Diatoms Red algae Amoebas Cellular slime molds Euglena Trypanosomes Animals Leishmania Fungi Sulfolobus Green nonsulfur bacteria Thermophiles (Mitochondrion) Spirochetes Chlamydia Halophiles COMMON ANCESTOR OF ALL LIFE Green sulfur bacteria BACTERIA Methanobacterium Cyanobacteria (Plastids, including chloroplasts) ARCHAEA

4. Prokaryote “Before nucleus” Characteristics: • Unicellular • 1-5 μm diameter • Cell walls -Maintains shape -Provides protection -Prevents lysis in a hypotonic environment

5. Common Shapes of Prokaryotes • Coccus - round • Bacillus - rod-shaped • Spirillum - spiral-shaped

6. Eubacteria Clustering • Diplo - a prefix used with the shape name to indicate pairing of cells. • Strepto - a prefix used with the shape name to indicate chains. • Staphylo - a prefix used with the shape name to indicate clusters

7. Gram Staining • Gram-positive bacteria • purple crystal violet stain is trapped by the layer of peptidoglycan which forms the outer layer of the cell. • Gram-negative bacteria • outer membrane of lipopolysaccharides prevents the stain from reaching the peptidoglycan layer. • outer membrane is then permeabilized by acetone treatment, and the pink safranincounterstain is trapped by the peptidoglycan layer .

8. Gram-positive and Gram-negative Bacteria

9. Prokaryotes and a Eukaryotic cell

10. Fimbriae 200 nm Figure 27.5 Fimbriae and Pili • Allow bacteria to stick to their substrate or other individuals in a colony

11. Prokaryotic Flagella About half of prokaryotes are motile

12. Flagellum Filament 50 nm Cell wall Hook Plasma membrane Basal apparatus ProkaryoticFlagella

13. Generalized reproduction of a prokaryote binary fission 1 Like mitosis, DNA replicates and the bacteria divides 2 conjugation One cell passes DNA to another through a sex “pilus” 3 transformation A bacteria takes up DNA from its liquid surroundings 4 transduction Bacterial viruses carry portions of DNA from one bacteria to another The major source of genetic variation in prokaryotes is mutation

14. Bacteria can share genetic material!!!!! • Transformation

15. Bacteria can share genetic material!!!!! • Conjugation

16. Bacteria can share genetic material!!!!! • Transduction

17. Plasmids

18. Plasmids

19. Prokaryote Colonies in Culture

20. Endospores • Bacillus anthracis • Can remain viable in harsh conditions for centuries

22. Oxygen Requirements • Obligate aerobes • Must have oxygen • Cellular Respiration • Obligate anaerobes • Are poisoned by oxygen • Fermentation or anaerobic respiration • Facultative anaerobes • Use oxygen if it is available • No oxygen – fermentation • Nitrogen Fixation • Use atmospheric nitrogen as a direct source of nitrogen. N2 NH4+

23. One of the most independent organisms on earth: Cyanobacteria (Anabaena)

24. Cyanobacteria Gloeothece Nostoc Calothrix Fischerella

26. Archaea Basic Archaeal Shapes : At far left, Methanococcus janaschii, a coccus form with numerous flagella attached to one side. At left center, Methanosarcina barkeri, a lobed coccus form lacking flagella. At right center, Methanothermus fervidus, a short bacillus form without flagella. At far right, Methanobacterium thermoautotrophicum, an elongate bacillus form.

27. Archaea Basic Archaeal Structure : The three primary regions of an archaeal cell are the cytoplasm, cell membrane, and cell wall. Above, these three regions are labeled, with an enlargement at right of the cell membrane structure. Archaeal cell membranes are chemically different from all other living things, including a "backwards" glycerol molecule and isoprene derivatives in place of fatty acids.

28. Archaea The side chains in the phospholipids of bacteria and eukaryotes are fatty acids, chains of usually 16 to 18 carbon atoms. Archaea do not use fatty acids to build their membrane phospholipids. Instead, they have side chains of 20 carbon atoms built from isoprene.

29. Archaebacteria • Methanogens • Anaerobic bacteria (oxygen is a poison) • Produce energy by converting H2 & CO2 into methane gas. • Live in swamps & marshes • Extreme Halophiles • “Salt-loving" bacteria • use salt to generate ATP for energy. • Thermoacidophiles: • Live in extremely acidic environments (pH less than 2) • extremely high temperatures (up to 110o C). • e.g. geothermal springs at Yellowstone National Park.

30. Archaebacteria

31. Prokaryotes Crucial to the Environment • Bacteria are the decomposers in ecosystems. • Some bacteria are symbiotic and live in association with other organisms. • The bacteria that reside in the human intestinal tract are mutualistic (both benefit);commensalistic(no harm, no benefit) bacteria reside on our skin; and parasitic(only they benefit, we suffer) bacteria cause a wide variety of diseases. • The cyanobacteria are photosynthetic in the same manner as plants.

32. Importance to Humans • Associated with good health – natural part of flora • Nitrogen fixation • Recycling nutrients • Sewage Treatment • Decomposers, breaking down the remains of organic matter in dead plant and animal waste.  • Used to help clean up environmental disasters caused by humans, such as chemical and oil spills • Foods and medicines • sour cream, yogurt, cottage cheese, sauerkraut and pickles, wine • antibiotics

33. How bacteria cause disease • Some bacteria produce toxins that can damage cells. • Endotoxin - made up of lipids and carbohydrates associated with the outer membrane of gram-negative bacteria. These toxins are some of the strongest poisons known to man and cause violent reactions in host organisms. • Exotoxin - proteins produced inside gram-positive bacteria cells and secreted into the environment. These toxins usually produce fever, weakness, and capillary damage. • Some bacterial proteins cause hypersensitivity reactions which can result in serious illness.

34. Antibiotics • Penicillin was the first antibiotic. It is highly effective against Gram+ bacteria, but much less so against Gram- bacteria. • Attacks the sugars that hold the capsule together. • Many bacteria are resistant to antibiotics. High mutation rates and misuse of antibiotics has caused a serious health threat that continues to escalate.

35. Antibiotic Resistance • When a population of bacteria is exposed to an Antibiotic, the most susceptible DIE.  • A Few Mutant bacteria that are resistant to the Antibiotic may continue to grow. • A Resistant Population then grows from these Mutant Bacteria through reproduction and genetic recombination. • These new Population are Antibiotic-Resistant.  This has resulted from the Over Use of Antibiotics.  Many diseases that were once easy to treat are becoming more difficult to treat.

36. Antibiotics

37. Escherichia coli…bad or good? E. Coli 0157:H7 - very toxic, found only in digestive tracts of corn-fed cattle Believed to have gotten its toxicity by conjugation from Shigella An estimated 73,000 cases of infection and 61 deaths occur each year in the United States alone Toxin prevents mRNA production in eukaryotic cells- causes cell death Adapted to an acidic environment- humans and corn-fed cattle, not grass-fed Killed at 160 degrees F E.Coli found in the intestines of most mammals, including humans Synthesizes Vitamin B Most strains harmless