1. BACTERIA

2. Structure of a Bacterium Peptidoglycan Cell wall Cell membrane Ribosome PiliDNA Flagellum

3. Structure of a Bacterium Capsule: some have a sticky gelatinous capsule around the cell wall (these bacteria are more likely to cause disease) Cell wall: gives the cell shape; composed of a peptidoglycan (sugar- protein complex) Plasma membrane: surrounds the cell and regulates what enters and leaves

4. Structure of a Bacterium Pilus: hairlike structures emerging from the cell surface; helps bacteria stick to a surface or exchange DNA between bacterial cells Flagellum: long, whiplike structure that enables movement

5. Structure of a Bacterium Chromosome: single DNA molecule arranged as a circular chromosome; not enclosed in a nucleus Plasmid: small circular chromosome piece containing a few genes

6. Classifying Bacteria Bacteria are classified according to: Shape Arrangement Gram stain

7. Classifying Bacteria Shape Spherical - Cocci Rod - Bacilli Corkscrew - Spirillae

8. Classifying Bacteria Arrangement Singular Pairs – Diplo Chains – Strepto Clusters – Stapylo

9. Classifying Bacteria Gram stain Staining method involving two dyes The dye absorbed by the bacteria depends on properties of the cell wall Bacteria are either Gram positive or Gram negative Positive stain bluish-purple Negative stain reddish-pink

10. Prokaryote Cell Wall Structure peptide side chains cell wall peptidoglycan plasma membrane protein Gram-positive bacteria Gram-negative bacteria peptidoglycan plasma membrane outer membrane outer membrane of lipopolysaccharides cell wall peptidoglycan = polysaccharides + amino acid chains lipopolysaccharides = lipids + polysaccharides That’s important for your doctor to know! Gram-Positive bacteria

11. Metabolism Obligate aerobes – must have oxygen to survive Obligate anaerobes – cannot live if oxygen is present Facultative anaerobes- can live either with or without oxygen

12. Archaebacteria & Bacteria Classification 3 Domain system reflects a greater understanding of evolution & molecular evidence Bacteria: Eubacteria Archae: Archaebacteria Eukaryotes: Protists Plants Fungi Animals Prokaryote Eukaryote

13. Classification of Bacteria All bacteria are prokaryotes Very simple organisms All are unicellular In general, they are smaller than eukaryotes Circular DNA which is not enclosed in a nucleus Lack membrane-bound organelles

14. Classification of Bacteria Archaebacteria Eubacteria Heterotrophic eubacteria Autotrophic eubacteria Chemosynthetic eubacteria

15. Archaebacteria a.k.a. Extremophiles Live in oxygen-free environments Obtain energy from sun or inorganic molecules

16. Archaebacteria: Thiobacilli Heat- and acid-loving bacteria Live in sulfur springs

17. Archaebacteria: Thiobacilli Consume sulfur Combine it with oxygen to produce energy Produce sulfur dioxide as by-product

18. Archaebacteria: Thiobacilli Sulfur dioxide can combine with water to form sulfuric acid

19. Archaebacteria: Halobacteria Salt-loving bacteria Live in saturated salt water like the Great Salt Lake

20. Archaebacteria: Halobacteria Produce purple pigments Use purple pigment to carry out photosynthesis the way plants use chlorophyll

21. Archaebacteria: Alkalophytes Live in aquatic environments with high pH Forms the food basis upon which thousands of large organisms are dependent Lake Nakuru

22. Archaebacteria: Methane Bacteria Cannot live in the presence of oxygen Live in stomachs of cows and sewage treatment ponds

23. Archaebacteria: Methane Bacteria Obtain energy from CO 2 and hydrogen gas

24. Archaebacteria: Deep Subsurface Bacteria Live in rocks beneath Earth’s surface (as deep as 3,000 feet)

25. Archaebacteria: Deep Subsurface Bacteria Obtain energy from H + produced from reaction between minerals in rock and groundwater seeping in

26. Classification of Bacteria Archaebacteria Eubacteria Heterotrophic eubacteria Autotrophic eubacteria Chemosynthetic eubacteria

27. Heterotrophic Eubacteria Obtain food from other living organisms parasites Obtain food from dead organisms or organic waste Recycle nutrients in decomposing organic material

28. Classification of Bacteria Archaebacteria Eubacteria Heterotrophic eubacteria Autotrophic eubacteria Chemosynthetic eubacteria

29. Autotrophic Eubacteria Obtain energy from light Perform photosynthesis

30. Autotrophic Eubacteria Cyanobacteria Most contain blue-green pigment (but some are red or yellow) Form chains: not unicellular

31. Classification of Bacteria Archaebacteria Eubacteria Heterotrophic eubacteria Autotrophic eubacteria Chemosynthetic eubacteria

32. Chemosynthetic Eubacteria Obtain energy from breakdown of inorganic substances (S and N compounds) Key for agriculture: Convert atmospheric N to a form plants can use

33. Reproduction in Bacteria Can reproduce rapidly (every 20 minutes) Luckily, most run out of nutrients and water before the colony gets very large Most reproduce by binary fission Bacterium copies its chromosome Old chromosome and copy attach to the plasma membrane at opposite ends Cell grows and becomes larger

34. Reproduction in Bacteria Most reproduce by binary fission Growth causes two chromosomes to separate Partition forms and separates the cell into two Each new cell has one copy of the original chromosome Creates two cells genetically identical to one another

35. Genetic Exchange in Bacteria Conjugation Sexual form of bacterial reproduction One bacterium passes all or part of its chromosome to another cell Transfer occurs across pili Creates two bacteria genetically different from one another They then reproduce by binary fission

36. Transduction: Transfer of genes from one bacterium to another by a bacteriophage. Ex. Toxin gene in Corynebacterium diphtheriae Genetic Exchange in Bacteria

37. Transformation: Taking in DNA from the outside environment. Ex. Rough Streptococcus pneumoniae transformed into smooth S. pneumoniae. Bacterial species in biofilm communities. Genetic Exchange in Bacteria

38. Survival If conditions become less than ideal some bacteria can form endospores Tough outer covering resistant to: Drying out Temperature extremes (boiling water) Harsh chemicals

39. Survival Closturidium botulinum Produces a deadly toxin Endospores can withstand boiling temperatures Canned foods must be pressure cooked to kill the endospores

40. Six week old infant with botulism, which is evident as a marked loss of muscle tone, especially in the region of the head and neck.

41. Survival Closturidium tetani Obligate anaerobe that produces a deadly neurotoxin Endospores are found on nearly every surface on the planet When endospores get into a moist, oxygen-free environment (such as inside a puncture wound) they germinate Reason for getting a tetanus shot

42. Tetanus

43. Survival Bacillus anthracis Aka. Anthrax Endospores live in soil When inhaled they germinate

44. Importance to Humans 1. Decomposers 2. Nitrogen-fixers 3. Biotechnology 4. Digestion

45. Decomposers Break down dead organisms and recycle the nutrients that make them Without decomposition we would run out of the molecules necessary for life

46. Nitrogen-fixation Plants and animals need nitrogen to make protein The atmosphere is mostly nitrogen but plants and animals can’t use it

47. Nitrogen-fixation Nitrogen-fixing bacteria convert nitrogen in the atmosphere into nitrogen plants can take up with their roots Animals get their nitrogen by eating plants

48. Biotechnology Production of foods like butter, cheese, and yogurt Cleaning up oil spills Synthesizing drugs and chemicals

49. Digestion Much of what we eat would pass through our bodies without being digested if we didn’t have bacteria in our digestive tracts They break down plant matter and synthesize vitamins for us

50. Bacterial Diseases Bacteria cause illness one of two ways: Breaking down host cells or tissues for food Normal metabolic processes generate toxins

51. Bacterial Diseases Most food-borne illnesses are caused by bacteria: E. coli comes from infected, undercooked beef Salmonella comes from infected, undercooked poultry (meat and eggs) Botulinum causes botulism – a deadly form of food poisoning

53. Controlling Bacteria Antibiotics are drugs that kill bacteria (NOT VIRUSES)

54. Controlling Bacteria Most bacteria like warm, moist, dark conditions Exposing them to other conditions kills them or slows reproduction

55. Controlling Bacteria Examples: Cooking foods makes it too hot for most bacteria to survive Refrigerating or freezing foods makes it too cold for them to reproduce Drying foods makes it impossible for bacteria to reproduce Pickling causes bacterial cells to burst