PROKARYOTES

*include bacteria and archaea
*singular: bacterium / plural: bacteria

PROPERTIES

1. Bacteria are classified into two kingdoms: Eubacteria (true bacteria) and Archaebacteria (Ancient Bacteria).
2. Bacteria are the MOST NUMEROUS ORGANISMS ON EARTH.
3. Organisms are classified as Bacteria by one characteristic: the lack of a cell nucleus (the name "prokaryote" means "before a nucleus")
4. Outer cell wall made of petidoglycan
5. Some move by means of a flagella (sing. flagellum)
6. Fimbrae - fibers that stick to surfaces (tooth decay, gonorrhea)
7. Region called the NUCLEOID which has a single circular chromosome, accessory rings of DNA called PLASMIDS

REPRODUCTION Occurs by BINARY FISSION (mitosis) and CONJUGATION (exchange of DNA) TRANSFORMATION- bacteria incorporate genes from dead bacteria TRANSDUCTION - viruses insert new genes into bacterial cells. This method is used in biotechnology to create bacteria that produce valuable products such as insulin ENDOSPORES - during unfavorable conditions, bacteria enclosed in a protective coat (Ex. Tetanus NUTRITION & NEEDS Obligate anaerobes - cannot grow in the presence of oxygen Facultative anaerobes - can grow with or without oxygen Aerobic - require oxygen Photoautotrophs - photosynthetic Chemoautotrophs - obtain energy from oxidizing inorganic compounds, such as ammonia Chemoheterotrophs - decomposers

 

 

 

 

 

 

 

 

 

 

Shape of Bacteria/ Naming

Bacterial Structure

 

Gram Stain

Gram's Stain is a widely used method of staining bacteria as an aid to their identification. It was originally devised by Hans Christian Joachim Gram, a Danish doctor.

Gram's stain differentiates between two major cell wall types.

Gram Negative -- light red or pink color	Gram Positive -- dark purple
Escherichia coli, Salmonella typhi, Vibrio cholerae and Bordetella pertussis	Staphylococcus epidermidis, Streptococcus pyogenes, and Clostridium tetani

 

Not all bacteria can be stained by Gram's method, the best-known exception belong to the genus Mycobacterium which have waxy cell walls.

How Gram Stains are Made

For more information on Gram Stains, see
http://www-micro.msb.le.ac.uk/video/Gram.html

 

 

 

Bacteria Images Buckman Laboratories Photo Gallery

Bacteria and Health - Some diseases caused by bacteria:

tetanus | botulism | Black Plague | Tuberculosis |gonorrhea | syphilis| Lyme disease | Strep throat | Pneumonia | Anthrax |necrotizing fasciitis (flesh eating bacteria) | toxic shock syndrome

• Alexander Fleming
• Noticed mold growing on petri dishes
• Bacteria did not grow where the mold was
• He isolated the chemical that killed bacteria, but it was not stable
• Howard Flory continued the work, later stabilized the chemical
• Fleming and Flory received the Nobel Prize in 1945