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.

Explanation:

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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