Diagram of Bacterial Cell
The bacterial cell. This happens to be what would be a Gram positive organism. By the way, I must site that this is not my own slide. It was taken from this particular book noted on the slide. It does show generally, the characteristics of the bacterial Gram positive cell, a very thick cell wall. That's the peptidoglycan layer. The inner membrane, which is the cytoplasmic membrane, and then see all these dots; they're ribosomes. I'm telling you when you see a cross section of a bacterium, it like they couldn't get more ribosomes in that cell if they tried. They're just packed. The ribosome is the protein factory of the organism. Then I've got all these strands kind of jumbled up here. This is the DNA region. Now, if this cell were carrying a plasmid, it would be kind of like separated from this big glob. It would be a circular DNA, as well. Like I said, a lot of times, most of the time it's carrying the resistance mechanisms, i.e. the genes that code for resistant properties. Here, I do another comparison for a Gram positive vs. Gram negative.
By the way, I guess all of you are familiar with Gram stain. It's just a way of distinguishing a large class of microorganisms of being either Gram positive, Gram negative depending upon how they respond to a stain. Again, the Gram positive has a very thick wall. Streptococcus for instance, also Staphylococcus, Lactobacillus. Then they have the cytoplasmic membrane. But with a gram negative, they have this additional outer membrane. That outer membrane, it contains a substance called lipopolysaccharide (LPS). This LPS can cause a lot of problems associated with gram negative infection. In the symptoms of disease, for instance, fever. LPS activates the fever process. In fact, if you go into the hospital and you're getting an IV drip containing water for injection, the water is called pyrogen free. That means that they've checked it and they've made sure that none of this stuff (LPS) is in there. Because if it's in there, you're going to get a fever even if you don't have an infection. So that's high quality water, believe me. That's better than the main water. And it's sterile of course. In Gram negatives, you also have an inner membrane. You have the peptidoglylcan layer here. In addition to containing LPS, this particular outer membrane can inhibit some antimicrobials from entering the cell. Of course those agents that can't pass the outer membrane are inactive against this type of organism.
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