Bacterial endotoxin is

Options

A. Lipopolysaccharide over the surface
B. Protein inside the cell
C. An excreted protein
D. None of the above.

Answer

**Step-by-Step Solution:**

1. **Understanding Bacterial Endotoxin:**
- Bacterial endotoxins are components associated with the outer membrane of certain bacteria, particularly Gram-negative bacteria.

2. **Composition of Endotoxins:**
- Endotoxins are primarily composed of lipopolysaccharides (LPS) and lipoproteins. These molecules are integral to the structure of the bacterial cell wall.

3. **Mechanism of Release:**
- Endotoxins are not secreted by the bacteria; instead, they are released when the bacterial cell wall is disrupted or when the bacteria die.

4. **Nature and Effects:**
- Although endotoxins can cause significant immune responses, such as fever, they are generally not fatal in small amounts.

5. **Analyzing the Options:**
- **Option 1:** Lipopolysaccharide over the surface - This is correct as endotoxins are indeed lipopolysaccharides found on the surface of Gram-negative bacteria.
- **Option 2:** Protein inside the cell - This is incorrect; endotoxins are not proteins found inside the cell.
- **Option 3:** An excreted protein - This is also incorrect; endotoxins are not secreted by the bacteria.
- **Option 4:** None of the above - This is incorrect since option 1 is correct.

6. **Conclusion:**
- The correct answer is **Option 1: Lipopolysaccharide over the surface**.

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