Your body is a planet!

1. 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

2. 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

3. 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

4. Bacteria Biology 11

5. 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 400 000 to 4 million species) *Only a minority of bacteria cause disease… majority are essential to all life on earth!

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

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

8. Classifying Bacteria II) Based on Shape

9. Name this Bacteria! • Staphylococcus

10. Name this Bacteria! • Streptobacillus

11. Name this Bacteria! • Spirillum

12. 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

14. BACTERIA Textbook Review • Read Pages 340-344 • Questions 1-7 page 344

15. Nutrition • Heterotrophs: • parasites (live in or around another organism) • saprophytes (decomposers) • Autotrophs: • photosynthetic autotrophs (cyanobacteria) • chemosynthetic autotrophs

16. Respiration Most are Aerobic: require O2 (oxygen) Some are: • facultative anaerobes: use O2 if available but can undergo anaerobic respiration or • obligate anaerobes: grow slowly or can be killed if O2 is present

17. Reproduction • Asexual reproduction a.k.a. binary fission • cell division (but not technically Mitosis… why??) • example of exponential population growth • Conjugation • exchanging of genetic material • simple sexual reproduction • Spore formation • some species can form an endospore in unfavourable conditions (dormant phase)

18. Binary Fission