1. Bacteria
Biology 11

2. General Characteristics:
lack a nucleus and membrane bound organelles (prokaryotic)
cell wall
microscopic / unicellular (some colonies)
asexual reproduction
roughly 4000 classified species (estimated to be around to 4 million species)
*Only a minority of bacteria cause disease… majority are essential to all life on earth!

3. General Diagram
capsule: protective layer outside the cell wall, only on some bacteria
pilli: bridging structures – assist with conjugation

4. Classifying Bacteria I) Based on Origin
Archaebacteria – ancient bacteria (live in extreme environments)
Eubacteria – “true” bacteria

5. Classifying Bacteria
II) Based on Shape

6. Name this Bacteria!
Staphylococcus

7. Name this Bacteria!
Streptobacillus

8. Name this Bacteria!
Spirillum

9. Classifying Bacteria III) Based on Cell Wall
Gram + have a thick cell wall composed of mostly peptidoglycan (stain violet)
Example: Staphylococcus aureus
Gram – have an outer cell membrane which hides the cell wall’s peptidoglycan (stain pink)
Example: Escherichia coli

11. Your Body is a Planet
Discover Magazine

12. Your body is a planet!
Staphylococcus On average, the skin supports about 1 trillion bacteria. The most common include staph, Streptococcus, and Corynebacterium, which metabolize sweat to produce body odor. Microbiologist Martin Blaser of the New York University School of Medicine sequenced the DNA of bacteria from the forearms of six people and discovered 182 separate species of bacteria. Most of those bacteria actually help to keep the skin healthy by competing with dangerous pathogens for nutrients. As Blaser explains, “I would hate to live without them.”
Source: Discover Magazine

13. Your body is a planet!
Dental streptococcus If you don't brush regularly, you probably have a biofilm of bacteria 300 to 500 cells thick on the surface of your teeth. The dominant species in this dental plaque are Streptococcus sanguis and S. mutans. Even if you brush diligently, these bacteria will still be there: They arrive soon after your teeth do and stay until they fall out. The bacteria ferment sugars and secrete gluey polymers that form the basis of plaque.
Source: Discover Magazine

14. Your body is a planet!
Firmicutes and Bacteroides At least 500 species of bacteria, weighing about 3.3 pounds, live inside the human gut. The majority are from one of two phyla, the Firmicutes and the Bacteroides. They break down carbohydrates and make essential nutrients like vitamins K and B12. They also crowd out harmful bacteria. As Cynthia Sears at Johns Hopkins Center for Global Health says, “Just by mere force of numbers, the bad bugs are beat out by the good bugs.”
Source: Discover Magazine

15. Discovery!
Penicillin

16. Agenda Bacteria textbook assignment – due tomorrow
Quiz tomorrow  review questions
Video: Understanding Bacteria

17. Resistant Bacteria
Animation
Video: Arms Race with a Superbug

18. Observing Bacteria Task: prepare a slide of yogurt
observe under HIGH power (start on low, then medium, them high)
record the shapes of bacteria that you see
If time: Look at the prepared slides of bacteria.