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

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

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

BacteriaBiology 11

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!

General Diagram

capsule: protective layer outside the cell wall, only on some bacteria

pilli: bridging structures – assist with conjugation

Classifying Bacteria

I) Based on Origin Archaebacteria – ancient bacteria (live in

extreme environments) Eubacteria – “true” bacteria

Classifying Bacteria

II) Based on Shape

Name this Bacteria!

Staphylococcus

Name this Bacteria!

Streptobacillus

Name this Bacteria!

Spirillum

Classifying BacteriaIII) 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

BACTERIA Textbook Review

Read Pages 340-344 Questions 1-7 page 344

Nutrition Heterotrophs:

parasites (live in or around another organism) saprophytes (decomposers)

Autotrophs: photosynthetic autotrophs (cyanobacteria) chemosynthetic autotrophs

RespirationMost are Aerobic: require O2 (oxygen)

Some are: facultative anaerobes: use O2 if available but

can undergo anaerobic respirationor

obligate anaerobes: grow slowly or can be killed if O2 is present

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)

Binary Fission