Bacterial Peptidoglycan Essay

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2007: Q7 - Write an essay on the structure and function of bacterial peptidoglycan Peptidoglycan is a polymer unique to prokaryotic cells consisting of polysaccharide and polypeptide chains. It is a key component of bacterial cell walls. Structure: Peptidoglycan is a highly crosslinked macromolecule. A disaccharide repeat region of N-Acetyl Muramic Acid and N-Acetyl Glucosamine forms its backbone. The presence of murein indicates that this is bacterial peptidoglycan as murein is never found in Archaea. Descending from the N-Acetyl Muaramic molecules are lypoproteins (stem peptides) consisting of D and L Amino Acids. A pentaglycine cross bridge joins the D-alinine and L-lysine Amino Acids, inter-linking the Disaccharide repeat regions. Teichoic acids are embedded in the plasma membrane (not shown in the diagram) they interweave through the peptidoglycan, attaching it to the bacterial cell. http://www.google.ie/imgres?q=peptidoglycan+diagram&hl=en&client=firefox-a&hs=5Jg&sa=X&rls=org.mozilla:en-US:official&biw=1173&bih=511&tbm=isch&prmd=imvns&tbnid=5DRtvUra9oY01M:&imgrefurl=http://pathmicro.med.sc.edu/fox/cell_envelope.htm&docid=0aWG7veP-RdY0M&imgurl=http://pathmicro.med.sc.edu/fox/sa-pep.jpg&w=567&h=488&ei=NSxVT6jrAYPvsgb85OzhCw&zoom=1&iact=hc&vpx=308&vpy=43&dur=4075&hovh=208&hovw=242&tx=128&ty=119&sig=112218279809207804119&page=1&tbnh=145&tbnw=168&start=0&ndsp=10&ved=1t:429,r:1,s:0 Peptidoglycan structure is slightly different between Gram positive bacteria (usually stain purple when Gram stained) and Gram negative bacteria (usually stain red when Gram stained). In Gram positive bacteria, such as Staphylococcus aureus, the peptidoglycan layer is much thicker than in Gram negative bacteria. Unlike Gram negative bacteria, Gram positive bacteria have no outer membrane. Antibiotics such as penicillin and ampicillin can be used to treat infections involving

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