Question

Outer layer of lipopolysaccharide is characteristic of

• A. Gram +ve rods
• B. Gram -verods
• C. Gram +ve cocci
• D. All of the above

Answer 1

Answer: (B)

Gram -verods

The Gram-negative cell wall is characterised by the presence of outer membrane, a thinner peptidoglycan layer and extensive periplasmic space surrounding the peptidoglycan. The uppermost layer of the outer membrane has lipopolysaccharide while the innermost layer is a typical lipid layer. Option B is correct. Gram-positive cells are characterised by the presence of a single thick layer of cell wall which is made up of peptidoglycan, teichoic acid and lipoteichoic acid. They lack outer membrane. This makes options A and C incorrect. Thus, the correct answer is option B.