12/15/2023 0 Comments Gram negative and gram positiveRetains crystal violet stain during gram stainingĭoes not retain a crystal violet stain, but gets counterstained with safranin, appearing pink or red after Gram staining.Įxamples include Staphylococcus, Streptococcus, and Clostridium.Įxamples include Escherichia coli, Salmonella, and Pseudomonas aeruginosa. Present in the outer membrane, form channels that allow the passage of molecules such as nutrients and antibiotics. Present in the cell wall, which helps with cell wall maintenance. Tend to produce endotoxins (toxins released upon bacterial death or lysis) Tend to produce exotoxins (toxins secreted by the bacteria) Generally less susceptible to antibiotics that target the cell wall due to the presence of the outer membrane, but can be targeted by other antibiotics such as aminoglycosides or fluoroquinolones Generally more susceptible to antibiotics that target the cell wall, such as penicillin Have an outer membrane outside the cell wall made of lipopolysaccharides This staining technique is essential in identifying and characterizing different types of bacteria. The ability of bacteria to retain the crystal violet stain determines their classification as either gram-positive or gram-negative. This method uses a dye called crystal or gentian violet to differentiate between various types of bacteria. While gram-negative bacteria have a thinner layer of peptidoglycan in their cell walls, which does not retain the crystal violet stain. Gram-positive bacteria have a thick peptidoglycan layer in their cell walls, which retains the crystal violet stain used during the staining process. The main difference between Gram-positive and negative bacteria is the cell walls because of their structure and composition. Gram-positive and gram-negative bacteria are two major groups of bacteria differentiated on the basis of their structure of the cell wall, and their response to a staining method called the gram stain. Role of Mahatma Gandhi in Freedom Struggle.
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