Q.71 Teichoic acid is composed of repetitive units of
(A) keto-deoxy octanoic acid
(B) glucose
(C) 𝑁-acetyl glucosamine
(D) glycerol
Teichoic acid features repetitive units of glycerol in Gram-positive bacterial cell walls. The correct answer to the multiple-choice question is (D) glycerol.
Correct Answer
Teichoic acids consist of glycerol phosphate or ribitol phosphate repeating units linked by phosphodiester bonds, with glycerol being the primary and most commonly referenced component in standard microbiology contexts. This polymer provides structural flexibility and cation-binding properties to the peptidoglycan layer. Glycerol-based repeats form the anionic backbone essential for bacterial cell wall integrity.
Option Analysis
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(A) Keto-deoxy octanoic acid: This refers to KDO, a component of lipopolysaccharide in Gram-negative bacterial outer membranes, not teichoic acids in Gram-positive bacteria.
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(B) Glucose: Glucose appears in glycolipid anchors or substituents of lipoteichoic acids but does not form the core repetitive units of teichoic acids.
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(C) 𝑁-acetyl glucosamine: N-acetyl glucosamine (GlcNAc) occurs in linkage units connecting teichoic acids to peptidoglycan or as side-chain modifications, not as the repeating backbone.
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(D) Glycerol: Glycerol phosphate serves as the fundamental repeating unit in most wall and lipoteichoic acids, confirmed across bacterial species like Bacillus subtilis and staphylococci.
