Question

Which of the following is exposed on the outer surface of a gram-negative bacterium?
A.O-antigen of lipopolysaccharide (LPS)
B. Polysaccharide portion of lipoteichoic acid (LTA)
C. Braun lipoprotein
D. Electron transport system components

Answer 1

c . Braun lipoprotein

Answer 2

Answer:

Option A. O-antigen of lipopolysaccharide (LPS) is exposed on the outer surface of a gram-negative bacterium.

Explanation:

• The outer surface of the gram-negative bacterium is made up of the lipopolysaccharide which surrounds the cell wall made up of peptidoglycan in the bacterium.
• Lipopolysaccharide is a large molecule made up of Lipids and a polysaccharide. It also has 0-antigen, outer core, and inner core, which are joined by the covalent bond.
• The O-antigen of the Lipopolysaccharide is a polymer of various oligosaccharides.
• This O-antigen forms the most outer layer of the gram-negative bacterium, hence option A is the correct answer.