Flora of the Skin, Nose, And Throat

BACTERIA   Most people know when they get sick. However, not all people know  the source of their sickness. Tiny microscopic organisms that live on the human skin and in our mucus membranes are the source of our sickness. While often these organisms live and reproduce without notice, sometimes they  penetrate our bodies natural barriers and cause infections.These infections can range from the benign and occassional zit to a more serious respiratory infection. Once these bacteria take hold, it is up to our bodies immune system and antibiotics to fight them off. So what exactly is BACTERIA?   

 
Key Characteristics of Bacteria


Prokaryotic
 Unicellular
Has cell walls
 Morphology


 
     Bacteria have cell walls containing peptidoglycan and are classified as gram-negative or -positive, depending on the amount of peptidoglycan in the cell wall. Gram-positive cell walls contain a thick layer of peptidoglycan and teichoic acids, while gram-negative cells contain a thin layer of peptidoglycan and have an outer lipopolysaccharide layer.
cell wall
           Image taken from Brock Biology of Microorganisms, 9th ed. Madigan/Martinko/Parker. Copyright 2000; pg. 68
Gram-positive cell wall  Gram-negative cell wall
gram-positive Image taken from Brock Biology of Microorganisms, 9th ed. Madigan/Martinko/Parker. Copyright 2000; pg. 71
 gram-negative


           IIn addition to cell wall structure, bacteria are classified and catagorized by their cell morphology. Morphology refers to the cell shape. Spherical bacteria are called cocci. Rod-shaped bacteria are called bacilli, and helical bacteria are called spirilla. With some bacteria, the cells are arranged in clusters, chains, or pairs.


morphology
Image taken from Brock Biology of Microorganisms, 9th ed. Madigan/Martinko/Parker. Copyright 2000; pg. 58
 morphology
Image taken from Brock Biology of Microorganisms, 9th ed. Madigan/Martinko/Parker. Copyright 2000; pg. 58
       







Home  A Wonderful World of Bacteria
 Page 1 Aseptic Technique
 		Page 2 History
 		Page 3 Skin Bacteria
 		Page 4 Nasal and Throat Bacteria