1. Bacteria – 2 Domains (Archaebacteria and Eubacteria)
The closest estimate is that there are 5 million trillion trillion bacteria on Earth – that’s a 5 with 30 zeroes after it.
Bacteria produce the air we breathe, clean the water we drink, and create fertile soil.
Less than one percent of bacteria cause diseases.

2. Bacteria structure – prokaryotic - notice no nucleus
plasmid

3. Bacterial Reproduction
Binary Fission – some bacteria can divide as often as every 20 minutes!
Binary fission is an asexual reproduction process. All offspring should be genetically identical to the parent cell and to each other.

4. Binary Fission

5. Methods of DNA Exchange
Even though bacteria reproduce asexually, they show methods of exchanging DNA pieces that increases their variability. There are 3 main methods:
a) Conjugation
b) Transduction
c) Transformation

6. Methods of Exchanging DNA
Conjugation – two bacteria join by a cytoplasmic bridge and exchange small circles of DNA called plasmids. The cells may in this way exchange useful information.

7. Conjugation
Conjugation animation

8. Methods of Exchanging DNA
Transduction - the process by which DNA is transferred from one bacterial cell to another by infection with a virus. Viruses that infect bacteria are called bacteriophages.
Bacteriophage

9. Transduction
Bacterial transduction animation

10. Methods of Exchanging DNA
Transformation- a living bacterial cell takes in the DNA from a dead bacterial cell. The DNA is then incorporated into the genome of the living cell.

11. Transformation
Bacterial transformation animation

12. DOMAIN Archaebacteria
Are EXTREMOPHILES (love extreme environments)
Are usually found in harsh environments – hot, salty, acidic.
Are ANCIENT– probably resemble the first bacteria and therefore the first life forms on the planet
Exobiologists (biologists who are looking for life on other planets or moons) guess that they should be looking for these types of cells. WHY?

13. Archaebacteria : Methanogens (generate methane)
produce methane – live in digestive tract of mammals, in swamps and sewage)

14. Archaebacteria: Thermophiles
can live in extremely hot water – found in hot springs

15. Halophiles
Live in very salty (halides) environments, such as the Great Salt Lake in Utah and the Dead Sea

16. Domain Eubacteria – true bacteria
Many types – modern bacteria
Classification is by:
Cell shape
Nutrition
Respiration

17. Cell Shape
Coccus - round
Bacillus - rod
Spirillum - spiral

18. Some bacteria grow alone, but others form colonies
Diplo…means two
Diplococcus
Diplobacillus or
Strepto… means chain
- as in streptococcus
- and streptobacillus
Staphylo… means cluster
As in staphlyococcus

19. Colonies growing into each other
Bacterial colonies consist of millions of bacterial cells growing together.
Sample Colony Characteristics
Size:  2mm diameter Shape:  Circular Elevation:  Convex Surface:  Smooth Density:  Opaque

20. Nutrition – Autotrophic or Heterotrophic
Autotrophs – make their own food
use sun’s energy or chemical energy
E.g. cyanobacteria (blue-green algae, nitrogen-fixing bacteria)

21. Most Bacteria are Heterotrophs
Escherichia coli
Spirillum
Found in intestines
Can cause certain STD’s
Anthrax
Deadly respiratory bacteria

22. 3 Types of Heterotrophic Bacteria
1. Saprophytic - Those bacteria who live and get nutrients by digesting dead plants/animals or their wastes. These bacteria are decomposing bacteria.
Saprophytic colony on tree trunk

23. 3 Types of Heterotrophic Bacteria
2. Parasitic – obtain food by living attached to or inside living organisms. These are harmful to the host organism, as they feed directly on the tissues of the organism.
These may cause disease (in which case, they are called pathogens).

24. Types of Heterotropic Bacteria
Parasitic bacteria
Streptococcus mutans – causes tooth decay
Staphylococcus aureus – causes pimples, boils, pneumonia, sepsis

25. 3. Types of Heterotrophic Bacteria
3. Mutualistic or Symbiotic bacteria – these bacteria feed off of other living organisms but have no harmful effect on the host organism.

26. Types of Heterotrophic Bacteria
Mutualistic or Symbiotic Bacteria
E. Coli – intestinal bacteria
Nitrogen fixing bacteria – plant roots

27. Respiration – process of getting energy from food
Aerobic bacteria
These bacteria need oxygen to metabolize (break down) food. If a bacterium cannot live without oxygen, it is known as an obligate aerobe.
example – tuberculosis (TB) bacterium
If a bacterium prefers to live with oxygen it is known as a facultative aerobe.
Tb lung

28. Anaerobic bacteria example: tetanus
These bacteria do not need oxygen. In some cases, these bacteria cannot survive in the presence of oxygen, in which case they are called obligate anaerobes.
example: tetanus
This baby probably got tetanus from honey – don’t give honey to a baby!

29. Some bacteria can live in the presence of oxygen, but do not require it for survival. These are known as facultative anaerobes.
Example: E. coli

30. How important are bacteria to the world?
Decomposition
Food web
Nitrogen cycle
Digestion
Food production
Bioremediation
Production of antibiotics

31. Food web

32. Nitrogen cycle
Bacteria recycling and incorporating nitrogen (N), for protein manufacturing.

33. Cow Digestion Bacteria in the stomach
- Help breakdown plant products for herbivores.

34. Foods from bacteria
cheese
yogurt
sauerkraut

35. Bioremediation – using microorganisms to rid environment of harmful substances
Ex – oil spill site
Hazardous waste site
Sewage treatment

36. Antibiotics are tested using Petri dishes and paper soaked in the antibiotic – anywhere the antibiotic inhibits growth, a zone of inhibition will be seen
Most effective
Not effective

37. Antibiotic Resistance
Antibiotics are chemicals that are selectively toxic (they are toxic to certain cells, and not others). They kill or inhibit the growth or reproduction of bacterial cells.
Some prevent bacterial cells from producing parts they need, other actually break the bacterial cell wall.

38. Antibiotic Resistance
Some bacteria have evolved defenses against antibiotics. They may inactivate the antibiotic or a mutation may have changed the bacterial compound that would normally be affected by the drug.
Because bacteria are able to exchange DNA (conjugation, transduction, transformation), it is easy for the resistance to be passed on to other bacteria.
Antibiotic resistance animation

39. Read section 2.2 pages 59- 66 and answer questions #1, 2, 3, 5, and 7