1. Prokaryotes

2. Taxis and Chemotaxis
Taxis: movement towards or away from a stimulus (signal) in the environment
Positive Chemotaxis  move TOWARDS nutrients or oxygen
Negative Chemotaxis  move AWAY from toxic chemicals

3. Cooperation in Colonies
Specialized cells within a colony (ex. Anabaena… some photosynthesize; others undergo nitrogen fixation)
Biofilms  individuals in colony secrete molecules to attract nearby cells = allows colony to grow

4. Molecular systematics
Emergence of “Archaea” domain
Diversity in prokaryotes is HUGE!
Horizontal gene transfer is prokaryote evolution (conjugation)

5. Impact of bacteria on Earth and Life
Bacteria are decomposers (break down dead/decaying material)
Cyanobacteria produce oxygen
Various symbiotic relationships (mutualism, commensalism, parasitism)

6. B. thetaiotaomicron In our digestive tract
Genes in bacteria help synthesize carbs, vitamins, and other nutrients (these are used by our bodies)
Help stimulate vascular network in intestinal lining (nutrient absorption)
In return, human cells induced to produce antimicrobial compounds to keep other bacteria out of our systems

7. Endo and Exotoxins EXOTOXINS ENDOTOXINS
Both exo and endotoxins produce toxic substances!
Exo: secreted by bacteria while alive (ex. cholera, botulism)
Endo: released once bacteria die
Toxins in cell wall (ex. salmonella)

8. Bacterial Benefits! Used in production of some cheeses and yogurt
Bioremediation  removing pollutants from soil, air and water
Metal extraction from ores
Genetic engineering  production of important vitamins, antibiotics, and hormones

10. Bacterial Reproduction… Quick Facts
Reproduction happens FAST
Can reproduce within 20 minutes
Binary Fission
Asexual form of reproduction
Most bacteria reproduce this way
Let’s check out the diagram…

11. Let’s check out this diagram…
Conjugation
A sexual “form” of reproduction
Protein “bridge” forms between 2 bacteria… allows for transfer of a SMALL piece of genetic info
Bacteria get new genetic info = increased DIVERSITY within the bacterial population!
Let’s check out this diagram…

12. Endospore Formation
Promotes bacterial survival in difficult environmental conditions
Unfavourable Conditions: lack of food; pH not optimal; too hot/cold
Endospore forms to protect genome
Bacteria remains dormant until…
Favourable conditions return
One last diagram…

13. Interesting Bacterial Groups…
Bacteria- diverse group
Archaea
Extreme thermophiles: live in hot environments (thermal vents in ocean, volcanic springs)
Extreme halophiles: live in very salty environments (Dead Sea, salt flats)
Methanogens: anaerobes (poisoned by oxygen)- use CO2 to oxidize H2 & release methane in the process
* All other organisms fall into the Domain Eukarya (Eukaryotes)