• Ahmad Wagih Abdel (Halim)


  • All bacteria are haploid structures; they can trap iron using siderophores, and can also perform fermentation processes.

  • Gram-positive bacteria appear violet because they absorb cresyl violet stain.

  • Gram-negative bacteria appear red because they absorb safranin stain.

  • Cell wall of bacteria is mainly made up of peptidoglycan:
    1. 1.

      Gram positive: It is thick with extensive cross-linking.

    2. 2.

      Gram negative: It is thin with minimal cross-linking.



Gram-Positive Bacteria

  • Cell envelope from inside out is formed of two layers:
    1. 1.

      Cytoplasmic membrane: A lipid bilayer spanned by proteins. This layer, unlike animals’ membranes, contains no sterols.

    2. 2.

      Cell wall: Formed of 3 P’s—Peptidoglycan, Polysaccharides, Proteins—and an antigenic determinant known as teichoic acid.


Gram-Negative Bacteria

  • Cell envelope from inside out is formed of three layers:
    1. 1.

      Cytoplasmic membrane: Lipid bilayer spanned by proteins

    2. 2.

      Cell wall: Very thin peptidoglycan layer with no teichoic...


Human Immunodeficiency Virus Clinical Picture Toxic Shock Syndrome Tinea Capitis Benzathine Penicillin 
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Copyright information

© Springer Science+Business Media, LLC 2009

Authors and Affiliations

  1. 1.McLaren Regional Medical CenterFlintUSA

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