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Why does alcohol decolorize gram negative bacteria?
Gram Negatice bacteria contain a cell membrane made up of thinner peptidoglycan layer plus a lipopolysaccharide layer, unlike gram positves bacteria's thick peptidoglycan layer. Alcohol delcolourizes gram negative bacteria because it disrupts the lipopolysaccharide and the crystal violet-iodine complex is able to now pass through the thin layer of peptidoglycan left leaving no crystal violet colour in the gram negatice bacteria that can now take up the red/pink colour of the safranin introduced be the subsequent counterstaining procedure.
What is gram negative and gram positive bacteria?
They have different cell walls.
Why are some bacteria gram-positive and some gram-negative?
During a gram stain some bacteria retains the stain because they are gram positive with thicker walls . If the bacteria does not stain either it is an endospore bacteria or gram negative with thinner walls, so colorless or red color.
Do prokaryotic cell walls contain peptidoglycan?
prokaryotes are bacterial cells. Bacterial cells can be either gram positive or gram negative. If the cell wall is gram positive it will have a cell membrane covered by MULTIPLE layers of peptidoglycan with strings of techolic acid going thru it. If the cell wall is gram negative it will have a cell membrane covered by ONE layer of peptidoglycan and an outer membrane surrounding it.
Why does gram-negative bacteria not retain the purple color in the Gram staining procedure?
Gram-negative bacteria do not retain the purple color in the Gram staining procedure because their cell walls have a thinner layer of peptidoglycan, which does not hold the crystal violet dye as effectively as the thicker peptidoglycan layer in Gram-positive bacteria.
Why does alcohol decolorize gram negative bacteria?
Gram Negatice bacteria contain a cell membrane made up of thinner peptidoglycan layer plus a lipopolysaccharide layer, unlike gram positves bacteria's thick peptidoglycan layer. Alcohol delcolourizes gram negative bacteria because it disrupts the lipopolysaccharide and the crystal violet-iodine complex is able to now pass through the thin layer of peptidoglycan left leaving no crystal violet colour in the gram negatice bacteria that can now take up the red/pink colour of the safranin introduced be the subsequent counterstaining procedure.
Why would bacteria stain gram variable?
A gram-negative cell will lose its outer membrane and the peptidoglycan layer is left exposed. or it is best to use younger cells ( 12-24hr) because older gram positive bacteria are subject to break down of the cell wall by enzymes that are produced with age which may result ingram variable staining.
How does thickness of peptidoglycan affect the outcome of gram stain?
For Gram Stain experiment. The gram-positive, g+, which stained purple in color (use Crystal violet) as the bacteria contain a thicker layer of peptidoglycan with no lipopolysaccharide and protein bound the outer membrane of the bacteria (bacteria A). The gram-negative, g-, which stained in red (if the safranin (red dye/counter stain is use) appear due to the bacteria (bacteria B) which lack of peptidoglycan and it is bound by a lipopolysaccharide and protein layer. The thicker the peptidoglycan, the more coloring agent (crystal violet ions, CV+) it can absorb. Hence, give more purple in color to the bacteria and this will be the gram-positive, g+ bacteria. On the other hands, bacteria B seem has thinner peptidoglycan thus it absorb less purple color from the CV+, and after decolourise (using alcohol) and stained with safranin (red dye), only the bacteria with lack of peptidoglycan change to red hence we can say bacteria B as gram-negative, g-. Hence the outcome is the bacteria with thicker peptidoglycan layer be the gram-positive, g+(purple color) while the thinner peptidoglycan layer be the gram-negative, g-. (red color)
How does thickness of peptidoglycan affect gram stain outcome?
For Gram Stain experiment. The gram-positive, g+, which stained purple in color (use Crystal violet) as the bacteria contain a thicker layer of peptidoglycan with no lipopolysaccharide and protein bound the outer membrane of the bacteria (bacteria A). The gram-negative, g-, which stained in red (if the safranin (red dye/counter stain is use) appear due to the bacteria (bacteria B) which lack of peptidoglycan and it is bound by a lipopolysaccharide and protein layer. The thicker the peptidoglycan, the more coloring agent (crystal violet ions, CV+) it can absorb. Hence, give more purple in color to the bacteria and this will be the gram-positive, g+ bacteria. On the other hands, bacteria B seem has thinner peptidoglycan thus it absorb less purple color from the CV+, and after decolourise (using alcohol) and stained with safranin (red dye), only the bacteria with lack of peptidoglycan change to red hence we can say bacteria B as gram-negative, g-. Hence the outcome is the bacteria with thicker peptidoglycan layer be the gram-positive, g+(purple color) while the thinner peptidoglycan layer be the gram-negative, g-. (red color)
What is the difference between cell wall of gram positive and gram negative bacteria.?
Gram positive bacteria cell walls have a thick layer of Peptidoglycan and no periplasmic space. Gram negative bacteria cell walls have inner and outter cytoplasmic membranes with a periplasmic space in between. these also have a thin layer of Peptidoglycan. The outter cytoplasmic membrane of gram negative bacteria contains lipopolysaccharides.
What are cell walls made of if they protect some bacteria from damage?
Cell walls of bacteria are made of peptidoglycan, a unique molecule composed of sugars and amino acids. In addition, some bacteria have an extra layer of protection outside the peptidoglycan layer, such as a capsule or slime layer, which help protect the bacteria from damage and harsh environments.
Why are Gram-positive bacteria more susceptible to the effects of penicillin than Gram-negative bacteria?
Penicillins have a bacteriocidal effect on Gram-positive bacteria. In Gram-positive cells, peptidoglycan makes up as much as 90% of the thick, compact cell wall, and is the outermost layer. Penicillins are not effective against Gram-negative bacteria, which have cell walls in which peptidoglycan is not the outermost layer, but that lies between the plasma membrane and a lipopolysaccharide (LPS) outer membrane. Penicillin cannot access the peptidoglycan of Gram-negative cells.
Function of iodine in staining?
iodine act as a mordant..on the gram positive bacteria which got really thick and abundence of peptidoglycan layer, the crystal violet will fix to the peptidoglycan layer..meanwhile in gram negative bacteria which is lack of peptidoglycan layer, the alcohol or acetone will wash it away
Gram-positive bacteria have a thick cell wall composed of?
Gram positive bacteria are so called because their cell walls are one thick layer of peptidoglycan, basically, so the stain is trapped in the cell wall and not rinsed away.
Why gram positive bacteria typically more resistant that gram negative bacteria to antibiotics that disrupt plasma membranes such as polymyxin B?
Polymixin antibiotics interact with the lipopolysaccharide molecule of Gram negative bacteria. This component forms the outer leaflet of the outer membrane. Gram-positive bacteria do not have an outer membrane or lipopolysaccharide and thus polymixin antibiotics are unable to bind to the cell.
What cell structures is significantly different between Gram positive and Gram-negative bacteria?
The difference between a gram positive and gram negative bacteria is the thickness/presence of the peptidoglycan layer secreted on the outside of the plasma membrane
What cell structure is significantly different between gram-positive and gram-negative bacteria?
The difference between a gram positive and gram negative bacteria is the thickness/presence of the peptidoglycan layer secreted on the outside of the plasma membrane
