Gram positive: Difference between revisions
Added more text |
Reformatted the page. Cleaned up the text. Removed some stray code. |
||
| Line 1: | Line 1: | ||
The Gram-positive [[Bacteria|bacterial]] [[Cell wall|cell wall]] is one of the two types of bacterial cell walls the other being [[Gram negative|Gram-negative]] cell walls. The Gram-positive cell walls are mainly composed of [[Peptidoglycan|peptidoglycan]] although they also consist of surface [[Proteins|proteins]], [[Teichoic acids|teichoic]] and [[Lipoteichoic acid|lipoteichoic acids]] the latter of which connects the cell wall to the cell membrane. The teichoic and lipoteichoic acids contribute to the positive charge of the bacterial cell surface and they are [[Glycerophosphate|glycerophosphate]] or [[Ribitol phosphate|ribitol phosphate]]- containing acidic polysaccharides. | The Gram-positive [[Bacteria|bacterial]] [[Cell wall|cell wall]] is one of the two types of bacterial cell walls the other being [[Gram negative|Gram-negative]] cell walls. The Gram-positive cell walls are mainly composed of [[Peptidoglycan|peptidoglycan]] although they also consist of the surface [[Proteins|proteins]], [[Teichoic acids|teichoic]] and [[Lipoteichoic acid|lipoteichoic acids]] the latter of which connects the cell wall to the cell membrane. The teichoic and lipoteichoic acids contribute to the positive charge of the bacterial cell surface and they are [[Glycerophosphate|glycerophosphate]] or [[Ribitol phosphate|ribitol phosphate]]- containing acidic polysaccharides. | ||
The thick layer of peptidoglycan enables the cell wall retain the purple colour of [[Crystal violet|crystal violet]] upon constriction consequent upon treatment with [[Iodine|iodine]]. Thus Gram-positive bacterial cell walls stain purple. | The thick layer of peptidoglycan enables the cell wall to retain the purple colour of [[Crystal violet|crystal violet]] upon constriction consequent upon treatment with [[Iodine|iodine]]. Thus Gram-positive bacterial cell walls stain purple. | ||
Examples of Gram-positive bacteria include ''[[Staphylococcus aureus|Staphylococcus aureus]]'', ''[[Streptococcus pyogenes|Streptococcus pyogenes]]'' and [[Streptococcus pneumonia|''Streptococcus pneumonia'']] amongst others | Examples of Gram-positive bacteria include ''[[Staphylococcus aureus|Staphylococcus aureus]]'', ''[[Streptococcus pyogenes|Streptococcus pyogenes]]'' and [[Streptococcus pneumonia|''Streptococcus pneumonia'']] amongst others<ref name="Kaiser, G.">Kaiser, G. (2012) The Prokaryotic Cell: Bacteria. http://faculty.ccbcmd.edu/courses/bio141/lecguide/unit1/prostruct/gpcw.html. The Community College of Baltimore County.</ref>. | ||
= | === The structure of the Gram-positive peptidoglycan cell wall === | ||
[[Peptidoglycan|Peptidoglycan]] is made from monomers called glycan tetrapeptides, these are linked together in chains which are in turn linked together. In gram positive bacteria the | [[Peptidoglycan|Peptidoglycan]] is made from monomers called glycan tetrapeptides, these are linked together in chains which are in turn linked together. In gram-positive bacteria the crosslink is a [[Peptide|peptide]] interbridge which is different in its structure depending on the bacterial strain, in [[Staphylococcus aureus|Staphylococcus aureus]] the interbridge is made from five [[Glycine|glycine]] residues<ref>Madigan Micahel T, Martinko John M, Bender Kelly S, Buckley Daniel H, Stahl David A. “Brock biology of microorganisms” 14th edition, Pearson education limited, 2014.</ref>. | ||
=== References === | === References === | ||
<references /> | <references /> | ||
Revision as of 14:07, 5 December 2017
The Gram-positive bacterial cell wall is one of the two types of bacterial cell walls the other being Gram-negative cell walls. The Gram-positive cell walls are mainly composed of peptidoglycan although they also consist of the surface proteins, teichoic and lipoteichoic acids the latter of which connects the cell wall to the cell membrane. The teichoic and lipoteichoic acids contribute to the positive charge of the bacterial cell surface and they are glycerophosphate or ribitol phosphate- containing acidic polysaccharides.
The thick layer of peptidoglycan enables the cell wall to retain the purple colour of crystal violet upon constriction consequent upon treatment with iodine. Thus Gram-positive bacterial cell walls stain purple.
Examples of Gram-positive bacteria include Staphylococcus aureus, Streptococcus pyogenes and Streptococcus pneumonia amongst others[1].
The structure of the Gram-positive peptidoglycan cell wall
Peptidoglycan is made from monomers called glycan tetrapeptides, these are linked together in chains which are in turn linked together. In gram-positive bacteria the crosslink is a peptide interbridge which is different in its structure depending on the bacterial strain, in Staphylococcus aureus the interbridge is made from five glycine residues[2].
References
- ↑ Kaiser, G. (2012) The Prokaryotic Cell: Bacteria. http://faculty.ccbcmd.edu/courses/bio141/lecguide/unit1/prostruct/gpcw.html. The Community College of Baltimore County.
- ↑ Madigan Micahel T, Martinko John M, Bender Kelly S, Buckley Daniel H, Stahl David A. “Brock biology of microorganisms” 14th edition, Pearson education limited, 2014.