1. Bacteria

2. What is a bacterium? Prokaryote Unicellular
Has a cell wall, DNA, and ribosomes
Found in variety of places

3. Fossils Evidence with stromatolites
How far back do we see fossils of bacteria?
3.5 billion years
Evidence with stromatolites

4. Classification Two kingdoms of Bacteria:
Archaebacteria (ancient bacteria)
Harsh environments
Primitive
Eubacteria (true bacteria)
Found anywhere
Cause diseases

5. Archaebacteria
Absence of peptidoglycan (component of bacterial cell wall)
Live in extreme environments: swamps, salt lakes, hot springs, volcanic vents, hydrothermal vents

6. Examples of Archaebacteria
Methanogens: found in swamps, intestines of animals
Extreme halophiles: salt-loving; live in Great Salt Lake and Dead Sea; use salt to make ATP
Thermoacidophiles: extremely acidic environments with high temperatures such as a hot spring; survive in 110 °C (230 °F) and a pH of 2; live near volcanic or hydrothermal vents

7. Eubacteria Presence of peptidoglycan in cell walls
Live everywhere on earth except extreme environments

8. Eubacteria Shapes Cocci – spheres Bacilli – rod Spirilla – spiral
Occur in chains: strep
Occur in clusters: staph
Examples: Streptococcus, Staphylobacillus
Lactobacilli: rod-shaped
Spirochaeta: spiral
Enterococci: spherical

9. Bacteria and archaea have similar structures.
plasmid DNA
flagellum
pili
Cell wall
Circular
DNA
flagellum
pili
plasmid
cell wall
chromosome
plasma membrance

10. Structure Cell wall Capsules and Pili Made of peptidoglycan
Function: Protection
Capsules and Pili
Capsule: outer covering; made of polysaccharides; protect the cell; some bacteria have this
Pili: short, hairlike protein structures on the surface of bacteria; help bacteria adhere to hosts

11. Prokaryotes provide nutrients to humans and other animals.
Prokaryotes live in digestive systems of animals.
make vitamins
break down food
fill niches

12. Bacteria help ferment many foods.
yogurt, cheese
pickles, sauerkraut
soy sauce, vinegar

13. Prokaryotes play important roles in ecosystems.
Prokaryotes have many functions in ecosystems.
recycle carbon, nitrogen, hydrogen, sulfur
fix nitrogen for plants

14. Bioremediation uses prokaryotes to break down pollutants.
oil spills
biodegradable materials

15. Some bacteria cause disease.
Bacteria cause disease by invading tissues or making toxins.
A toxin is a poison released by an organism.

16. Antibiotics are used to fight bacterial disease.
Antibiotics may stop bacterial cell wall formation.
Prevention is best method to fight bacterial disease.

17. Antibiotic

18. Genetic Recombination
Transformation – takes in DNA from the environment
Conjugation – transferring of DNA between bacteria
Transduction – a virus picks up DNA from its host and then the new viruses carry the DNA to a different host

19. Reproduction Asexual reproduction Makes more of the same
Looks like the parent
Bacteria use binary fission

20. Bacteria have various strategies for survival.
Prokaryotes exchange genes during conjugation.
conjugation bridge
TEM; magnification 6000x

21. Structure
Endospores
Resistant structure with a thick outer covering in order to survive harsh conditions; able to resist dehydration, high temperatures, chemicals, and radiation

22. Environment & Temperature
The temperature where bacteria may be found depends on the species.
Prokaryotes can be grouped by their need for oxygen.
obligate anaerobes are poisoned by oxygen
obligate aerobes need oxygen
facultative aerobes can live with or without oxygen

23. Nutrition Heterotrophic or autotrophic
Feed on dead and decaying material: decomposers
Use sunlight: photoautotrophs
Cyanobacteria
Use chemicals as source of carbon: chemoautotrophs
Found at ocean depths

24. Bacteria can evolve resistance to antibiotics.
Bacteria are gaining resistance to antibiotics.
A bacterium carries genes for antibiotic resistance on a plasmid.
A copy of the plasmid is transferred through conjugation.
Resistance is quickly spread through many bacteria.

25. Bacteria and Humans Antibiotic resistance
Because antibiotics have been overused, many diseases that were once easy to treat are becoming are not as easy to treat
Some bacteria prevent passage of an antibiotic
Some secrete enzymes that destroy or alter the antibiotic (penicillin-resistant)
Play Anti-Biotic Resistant Video