A Gram negative bacteria differ from a Gram positive bacteria in having

Options

A. Thick cell wall and is primarily made up of peptido- glycan
B. Complex cell envelope made up of three layers
C. cell wall of 20- 80 nm in thickness and also contains tightly bound techoid acids
D. Absence of cell wall lipids

Answer

To answer the question "A Gram negative bacteria differ from a Gram positive bacteria in having," we will analyze the key differences between these two types of bacteria.

### Step-by-Step Solution:

1. **Understanding Gram Staining**:
- Gram staining is a laboratory technique used to differentiate bacterial species into two groups based on the characteristics of their cell walls.
- Gram-positive bacteria retain the crystal violet stain used in the process, appearing purple, while Gram-negative bacteria do not retain the stain and appear pink after a counterstain is applied.

**Hint**: Remember that the color change during Gram staining is crucial for differentiating between Gram-positive and Gram-negative bacteria.

2. **Cell Wall Composition**:
- Gram-positive bacteria have a thick peptidoglycan layer (20-80 nm) in their cell wall, which retains the crystal violet dye.
- In contrast, Gram-negative bacteria have a much thinner peptidoglycan layer and possess an additional outer membrane.

**Hint**: Focus on the thickness of the peptidoglycan layer and the presence of an outer membrane when comparing the two types.

3. **Presence of Teichoic Acids**:
- Teichoic acids are present in the cell walls of Gram-positive bacteria but are absent in Gram-negative bacteria. This is a significant distinguishing feature.

**Hint**: Teichoic acids are a key component to remember when discussing the differences in cell wall structure.

4. **Outer Membrane and Lipopolysaccharides**:
- Gram-negative bacteria have an outer membrane that contains lipopolysaccharides (LPS), which contribute to the structural integrity of the bacteria and can trigger immune responses in hosts.
- Gram-positive bacteria lack this outer membrane.

**Hint**: Consider the presence of the outer membrane and its components when identifying characteristics of Gram-negative bacteria.

5. **Conclusion**:
- The primary difference between Gram-negative and Gram-positive bacteria is that Gram-negative bacteria have a thinner peptidoglycan layer, an outer membrane, and lack teichoic acids, while Gram-positive bacteria have a thick peptidoglycan layer and contain teichoic acids.

**Final Answer**: A Gram-negative bacteria differ from a Gram-positive bacteria in having an outer membrane and lacking teichoic acids.

### Summary of Key Differences:
- **Gram-negative bacteria**: Thin peptidoglycan layer, outer membrane, absence of teichoic acids.
- **Gram-positive bacteria**: Thick peptidoglycan layer, no outer membrane, presence of teichoic acids.