Which of the following best describes the structure assembled on top of the cytoplasmic membrane in Gram-positive bacteria?

• A. A single phospholipid bilayer with embedded proteins
• B. A thick layer of peptidoglycan containing teichoic acids
• C. A thin layer of peptidoglycan surrounded by a capsule
• D. An outer membrane containing lipopolysaccharides

Answer: (B)

Verified step by step guidance

1. Step 1: Understand the basic cell envelope structure of Gram-positive bacteria. Gram-positive bacteria have a cytoplasmic membrane and a thick cell wall but lack an outer membrane.
2. Step 2: Recall that the cytoplasmic membrane is a phospholipid bilayer with embedded proteins, common to all bacteria, but the question asks about the structure assembled on top of this membrane.
3. Step 3: Identify the main component of the cell wall in Gram-positive bacteria, which is a thick layer of peptidoglycan. This layer provides rigidity and shape to the cell.
4. Step 4: Recognize that teichoic acids are molecules embedded within the thick peptidoglycan layer in Gram-positive bacteria, playing roles in cell wall maintenance and ion regulation.
5. Step 5: Compare this to Gram-negative bacteria, which have a thin peptidoglycan layer and an outer membrane containing lipopolysaccharides, a structure absent in Gram-positive bacteria.