Which of the following statements is true? gram-positive bacteria have a single cell wall anchored to the cell membrane by lipoteichoic acid. porins allow entry of substances into both gram-positive and gram-negative bacteria. the cell wall of gram-negative bacteria is thick, and the cell wall of gram-positive bacteria is thin. gram-negative bacteria have a cell wall made of peptidoglycan, whereas gram-positive bacteria have a cell wall made of lipoteichoic acid.
Gram-positive bacteria have a single cell wall anchored to the cell membrane by lipoteichoic acid.
According to Gram stain test, bacteria can be divided into two main groups which differs mostly in the structure of the cell wall"Gram-positive bacteria-thick cell wall which consist of peptidoglycan layer that is attached to cell membrane via teichoic acids (lipoteichoic acids). Because of their thick wall, after the staining, the violet dye retains, so Gram positive bacteria appear purple-coloured.Gram-negative bacteria-thin peptidoglycan layer with two cell membranes: inner and outer membrane (lipopolysaccharides). Usually, Gram negative bacteria contain porins. After the staining, the dye does not retain, so this type of bacteria appear red coloured.
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Bacteria are divided into two groups, namely Gram-positive bacteria and Gram-negative bacteria. This division is done on the basis of reaction of the bacteria to Gram staining.
Gram-positive bacteria lack an outer membrane and consist of many layered peptidoglycan instead. Also, Gram-negative bacterial cell wall is not thick and Gram-positive bacterial cell wall is not thin. It is actually the other way round. The peptidoglycan layers in Gram-positive bacteria make their cell wall thick whereas the few peptidoglycan layers in Gram-negative bacteria make their cell wall thin.
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Hence, the options b, c and d are false.
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Gram-negative bacterial cell wall is made up of few layers of peptidoglycan along with some additional layers which are surrounded by the outer membrane. Cell wall of Gram-positive bacteria is made up of many layers of peptidoglycan and not of phospholipids.
The cell wall of Gram-positive bacteria is made up of only peptidoglycan. Many layers of peptidoglycan form its cell wall.
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Hence, the true answer is option Hopefully this is right if not I am sorry
I just did this test.
The correct answers are;
Gram staining is used for differentiation gram-positive from gram-negative bacteria based on the characteristic of their cell wall. Gram-negative bacteria have a thinner cell wall than gram-positive bacteria. In this staining, bacteria are first stained with crystal violet dye. Only gram-positive bacteria will be violet colored because they can retain the dye thanks to their cell wall. The second staining with fuchsine or safranin will give the red or pink color to the gram-negative bacteria.