3/10/14
    Today we start our class without any announcement. We directly proceed with the lecture. We continue learning about external and internal structure of prokaryote.
     We learn about function of the cell wall.
Not all cell wall of bacterial is identical.The cell wall can also divided into gram negative or gram positive.
Pic from: http://www.microbiologybytes.com/introduction/graphics/Prokaryotes4.gif.pagespeed.ce.D6rhDgjSld.gif

  1. Gram positive cell wall contain 90% of peptidoglycan.Gram positive cell wall contain teiochoic acid which was absent in negative gram cell wall.This teichoic acid use as antigenic specificity to determine pathogenic or not. It also contribute to acidity of cell wall. Two classes of teichoic acid:lipoteic acid (spans the peptidoglycan layer and is linked to the plasma membrane)
  2. Wall teichoic acid (link to peptidoglycan layer)
Gram positive cell wall do not contain outer membrane.

In gram negative cell wall 10% are peptidoglycan. Because of this gram negative cell wall are more vulnerable to mechanical breakage. Mechanical damage are too cold, too hot or centrifuge. The outer membrane provide a barrier to certain antibiotic,lysozyme, detergent, heavy metals,bile salts and certain dyes which means gram negative cell wall are more resistance .In outer membrane also contain porins which have enzyme degrade. B-lactamase can degrade penicilin. B-lactam antibiotic, contain B-lactam ring in their structure are degrade by B-lactamase.The lipid portion oflipopolysacharide is refer as endotoxin.Toxic when in host bloodstream or gastrointestinal tract.Endo must inside cell.The bacteria must presence .To work cell wall has to lies so toxin can be release.
Atypical cell walls which was not normal do not contain wall of peptidoglycan but contain sterols which almost same as cholesterol.For example Mycoplasma.Mycoplasma pneumoniae cause pheunomia.

Before this I never know that cell wall actually has many function. I only know the functions that related to maintain the cell shape. I was really quiet shock that we study about cell wall more detail there are consist of many substances and each substances has each roles. From my knowledge prevously, I thought all the cell wall of bacteria are the same but there are not the same there must be a difference

When lecture of internal structure of prokaryote we have to answer question through edmodo. All of the students were asked to bring their on device on this lecture.
We have to label the picture and describe the role which we can remeber.

What I have learn:
-The bacterial cell wall is not identical to each other.
-The gram negative cell wall is more resistance than gram positive.
-Atypical cell wall is not normal cell wall.
-Internal structure consist of plasma menbrane, nucleoid, plasmids,ribosome and endospore.



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