1. Prokaryotes
Ms. Cole

2. Prokaryotes
What do you know?

3. We are familiar with the harmful bacteria… Tuberculosis Cholera STD’s
Bubonic plague
Tuberculosis
Cholera
STD’s
food poisoning
But what about the beneficial bacteria.
Nitrogen fixers
Bioremediation
Pharmaceutical & food industries

4. Most Common Shapes Cocci (spherical) Bacillus (rod-shaped) Spiral
Spirillum (rigid helix)
Spirochete (flexible helix)
Vibrios (comma shaped)

5. Micrococcus coccus bacteria

6. Salmonella bacilli bacteria

7. Spiroplasma spirilla bacteria

8. Most prokaryotes have diameters in the range of 1-5 µm
largest prokaryote discovered so far has a diameter of 0.75 mm.
It is a sulfur-metabolizing marine bacterium from coastal sediments off Namibia.
Fig. 26.4
Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings

9. Bacteria and Archaea

10. Archaebacteria primitive prokaryotes unicellular
found in the harshest environments on Earth: sometimes called extremophiles

11. Bacteria “true bacteria”
mostly unicellular; some colonial or filamentous
Peptidoglycan in cell wall

12. Cell walls in Bacteria Gram Staining Gram-positive - purple
Very thick peptidoglycan
Gram-negative - pink
Thin layer of peptidoglycan
Outer membrane
Capsule
Surrounding the cell wall
Increased resistance to host defenses

13. Gram-positive cell wall

14. Gram-negative cell wall

15. Other Bacterial Structures
Pili
Protein structures that extend from the cell
Help bacteria adhere to surfaces
Flagella
Produce a rotary motion
Basal body, hook, and filament
Taxis
Chemo & photo

16. Bacterial flagellum

17. Review Genetic material Asexual reproduction Circular DNA molecule
Plasmids
Asexual reproduction
Binary fission
Budding
Fragmentation

18. Gene Transfer Transformation Transduction Conjugation
Intake of DNA fragments
Transduction
virus carries bacterial DNA between cells
Conjugation
Direct transfer of genes from one prokaryote to another

19. Metabolic Diversity Heterotrophs Autotrophs Photoheterotrophs
Chemoheterotrophs
Feed on dead organic matter
Autotrophs
Photoautotrophs
Chemoautotrophs

20. Oxygen Use Most bacteria are aerobic
Facultative anaerobes use oxygen if it is available
Obligate anaerobes carry on metabolism only anaerobically

21. Archaea - Extremophiles
Methanogens
Produce methane gas
Anaerobic environments
Extreme halophiles
Inhabit saturated salt solutions
Extreme thermophiles
Inhabit environments over 100°C

22. Symbiotic Review
Mutualism
Commensalism
Parasitism

23. Disease and Microbes 1/2 of human disease is caused by bacteria
some are opportunistic
Pathogens
Koch’s postulates
Exotoxins
Endotoxins

24. Koch’s Postulates
1. Find the same pathogen in each diseased individual.
2. Isolate the pathogen from a diseased subject and grow it in pure culture.
3. Use cultured pathogen to induce disease in experimental animals.
4. Isolate the same pathogen in the diseased experimental animal.

25. Antibiotics
Alexander Fleming discovers that Penicillium mold produces penicillin
Breaks peptidoglycan cross links
endospores

26. Copyright © 2002 Pearson Education, Inc
Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings

27. Table 27.3, continued
Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings

28. Quiz-page 2
List and describe at least 3 sources of genetic variation in bacteria.
List the four nutritional categories for bacteria. Define what each uses as an energy source and as a source of carbon atoms.
What are the 3 fundamental symbiotic relationships we have discussed. Briefly explain their differences.
List two of the three scientists who are remembered for their research on the microbial causes of disease. Give a specific example of what your listed scientists discovered.

29. Quiz-page 3
What is nitrogen-fixation? What genus of bacteria are responsible for this important part of the nitrogen cycle? Which family of plants share a mutualistic relationship with the aforementioned bacteria?
Who discovered penicillin? What is the target of its action? Why are Gram-positive bacteria more susceptible to this action than are Gram-negative bacteria?
What characteristics make a protist “animal-like”, “plant-like”, or “fungus-like”? Give an example of a protist in each of these groups.
Most fungi are either decomposers or parasitic. However, there are two groups of mutualistic fungi that we discussed. Choose one of these mutualistic relationships, give both organisms in the relationship and tell how each one is benefited.