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Name: Amir
Status: Student
Grade:  Other
Location: N/A
Country: United States
Date: March 2005


Question:
What is the rule of peptidoglycan (in bacteria cell wall)in bacteria resistant ?



Replies:
I'm not sure what you mean by "rule" in resistant bacteria. But peptidoglycan is a sugar-protein complex found in bacterial cell walls. It is made of two alternating sugar types that are found in long sheets. The sheets are linked together by four amino acids called tetrapeptides. So peptidoglycan is kind of like a chain link fence surrounding the outside of a bacterium. Many antibiotics work by "clipping" the tetrapeptide links that hold the wall together. This makes the wall unstable and the bacterium ruptures under osmotic pressure, killing the organism. Some bacteria have evolved ways to inactivate this mechanism. One way is to inactivate the antibiotic so it can't clip the tetrapeptides anymore. This is an enzyme called "penicillinase" (actually beta-lactamase) because it breaks down the penicillin before the penicillin can break down the cell wall. This makes the bacteria resistant to the penicillin.

The rule is that bacteria which have a cell wall comprised of peptidoglycan (sugar and amino acid molecules bonded together) are Gram positive meaning they take up Gram stain

vanhoeck



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