1. True false correction questions. Mark as T if true and F if false. If a state
ID: 191647 • Letter: 1
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1. True false correction questions. Mark as T if true and F if false. If a statement is false, you will need to correct it in order to receive credit for your answer. There could be more than one error in a statement. Your corrections must be substantial, meaning that it is not ok to remove or add a "not", or to mark something out but not replace it unless it is unavoidable. Make sure you replace the incorrect portion to get credit. If something is underlined, it cannot be changed. Bacillus and Staphylococcus will hold the primary stain during the iodine step, whereas Escherichia coli will not; this allows gram+ bacteria to be distinguished from gram- bacteria S. aureus and other gram + bacteria do not have any membranes as part of the cell walls; their cell walls contain teichoic acid, which has a full positive charge from the phosphorus present in the molecule.Explanation / Answer
First statement is true, because gram staining is a differential staining procedure that is used to distinguish gram positive such as Staphylococcus, Bacillus and gram negative bacteria such as E. coli. Gram-positive bacteria consist of thick cell wall that is made up of thick peptidoglycan layer, which stains purple. Peptidoglycan is a polysaccharide that have two subunits are N-acetyl glucosamine & N-acetyl muramic acid. Gram-positive bacteria are allow to retain the complex of crystal violet-iodine due to the presence of thick peptidoglycan layer, and stains the cells as purple.
Gram-negative bacteria consists of thin layer of peptidoglycan and lose the complex of crystal violet and iodine during decolorization with the alcohol, and retain the counter stain Safranin, that appear as reddish or pink.
Gram-positive cell wall composed of high percentage of teichoic acids that are important for integrity of cell wall.Teichoic acids provide the cell wall of gram-positive bacteria an overall negative charge because of the presence of phosphodiester bonds between monomers of teichoic acid. therefore second statement is false.
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