Bacteria

1. Bacteria Biology 11

2. Prokaryotic Cells • Unicellular • No nucleus • No membrane-bound organelles • Do contain DNA

3. 2 Kingdoms • Archaebacteria “ancient bacteria” • Eubacteria “true bacteria”

4. Archaebacteria: The Extremists • Live in harsh environments

5. Methanogens: • Produce methane • Live in oxygen free environments • Found in swamps, marshes, stomachs of cows • Sewage disposal plants- help breakdown sewage

6. Halophiles: Salt-loving • Live in salt pools left after a lake has evaporated • pools have high levels of magnesium and potassium salts • Utah’s Great Salt Lake and Middle East’s Dead Sea

7. 3. Thermoacidophiles: Heat- and acid-loving • Live around deep ocean vents • Temperatures are often above 100ºC • Anaerobic (without oxygen) • Live in hot, acidic waters of sulfur springs

8. Eubacteria • Live everywhere except extreme environments • Heterotrophs • Use organic molecules as food source • Some are parasites • Some are saprophytes (feed on dead organisms or organic wastes – break down and recycle nutrients)

9. 2. Photoautotrophs • Photosynthetic autotrophs - Live in places with sunlight • Cyanobacteria – contain chlorophyll (pigment) that traps the sun’s energy • Live in ponds, streams, and moist areas of land • Composed of chains of independent cells

10. 3. Chemoautotrophs • Make organic molecules • Obtain energy by breaking down compounds with sulfur and nitrogen and releasing the energy in the process called chemosynthesis • Bacteria in Plants– able to convert atmospheric nitrogen into the nitrogen-containing compounds that plants need

11. Bacteria Structure • Ribosomes- protein synthesis • Chromosome- single circular DNA molecule • Cell Wall- support and protection • Flagella- motility

12. Pilli (sing. Pillus) hair like structure to aid in reproduction and attaching to one another • Capsule- sticky, gelatinous, surrounds cell wall to protect against desiccation • Cytoplasm- thick liquid within cytoplasmic membrane • Plasmid- small circular piece of DNA

13. If Bacteria don’t have mitochondria, how do they get their energy? • Occurs at cell membrane

14. Identifying Bacteria • Bacteria are separated into two groups based on characteristics of cell wall • Cell walls made of peptidoglycan (sugar and amino acid molecules) which helps structure and maintain shape (target for antibiotics) • Technique called gram staining is used to do this

16. Gram Stain • First, crystal violet dye is added. Then, a second dye is added. • Gram + bacteria retain crystal violet dye • Gram – bacteria appear red or pink after a counterstain is added (commonly safranin)

17. Gram-positive: one thick layer of peptidoglycan (protein and sugar) Gram-negative: one thin layer of peptidoglycan and an outer lipid and sugar layer

18. Identifying Bacteria • Growth pattern • Diplo (paired arrangement) • Staphylo (grape arrangement) • Strepto (chain of cells) • Bacteria shape (plural) • Cocci (spheres) • Bacilli (rods) • Spirilla (spirals)

19. Strepto-Coccus

20. Strepto-Bacillus

21. Spirillum

22. How do bacteria get around? • Flagella vs Cilia • Flagella use whip like motions to move • Cilia use a beating motion to move (eukaryotes only)

23. Remember: • Bacterial DNA • Circular • Free floating in the bacterial cytoplasm

24. A well fed bacteria is two happy bacteria • ATP- when used, turns into ADP (Tri-phosphate or Di-phosphate) • Bacteria have a protein called DnaA that starts the process of DNA replication (first step in fission) • DnaA+ADP = nothing  ; DnaA+ATP = replication

25. Bacteria Reproduction 1. Asexual by binary fission • DNA replicated • DNA pulled to separate poles as bacterium increases in size • A partition forms and separate the cells • Results in genetically identical cells • Can be rapid –ideal conditions every 20 minutes

27. Plasmids • Extra circle of DNA that can replicate independently • Can be transferred to another Bacterium • Typically carries a beneficial trait. e.g. antibiotic resistance.

29. 2. Conjugation • Bacteria conjugate if one of them have special “F” factor (fertility factor) • The F+ bacteria (donor) makes a Pilus, and transfers the F plasmid to the F-recipient. • Recipient is now F+ • Results in a bacteria with new genetic composition

31. Spore Formation • Endospore: tiny structure that contains a bacterium’s DNA and a small amount of its cytoplasm • Encased by tough outer covering • Resists drying out, extreme temperature, harsh chemicals • If environmental conditions improve, then endospore germinate • To kill endospores, items must be sterilized (i.e. heated under high pressure)

33. Metabolism • 2 Types: Aerobic and Anaerobic • Aerobic Bacteria require oxygen to produce energy • Anaerobic Bacteria don’t require oxygen to produce energy

34. When typing Bacteria- Gram’s stain is #1, then comes how they make energy • Obligate Anaerobic (Can’t live with oxygen) • Facultative Anaerobic (can get by either way) • Obligate Aerobic (Can’t live without oxygen)

35. Where can they get energy from?

36. Importance of Bacteria Ecological Role • Production of nutrients • Nitrogen fixation • Vitamin K, B12 • Breakdown of cellulose • Breakdown of detritus • Prevention of pathogen colonization

37. Production of Nutrients • Soil microbes take nitrogen from atmosphere and make nitrogen containing compounds (nitrates, nitrites, etc) • Some exist in symbiotic relationships (eg. Termites, legumes, clover, alder, etc)

38. Some bacteria produce Vitamin K (E. coli) or B12, which are not produced anywhere else

39. Cellulose (plant fibers) cannot be broken down by eukaryotes • Many organisms exist in symbiotic relationships with bacteria in order to break down cellulose into usable sugars.

40. Break down of detritus • Bacteria clear landscape of dead matter • Returns nutrients to the soil

41. Prevention of colonization • Take up valuable real estate that pathogenic organisms would love to inhabit • Harmless or beneficial bacteria prevent harmful ones from colonizing