Branched chain lipids present in plasma membrane of Archaebacteria :

Options

A. Increases membrane fluidity and increase tolerance to extremes of heat as well as low `pH`
B. Decrease membrane fluidity and increase tolerance to extremes of heat as well as high `pH`
C. Stabilize membrane fluidity and increase tolerance to extremes of heat as well as low `pH`
D. Decrease tolerance to extremes of heat as well as low `pH`

Answer

To answer the question regarding the branched chain lipids present in the plasma membrane of Archaebacteria, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding Archaebacteria**:
- Archaebacteria are a group of microorganisms that are distinct from bacteria and eukaryotes. They often thrive in extreme environments.

2. **Identifying Lipid Structure**:
- The plasma membrane of Archaebacteria contains unique lipids that differ from those found in other organisms. These lipids are characterized by branched chain hydrocarbons.

3. **Role of Glycerol**:
- The branched chain lipids in Archaebacteria are based on glycerol. Glycerol serves as the backbone for these lipids.

4. **Ether Linkages**:
- Unlike the ester linkages found in the membranes of bacteria and eukaryotes, Archaebacteria have ether linkages in their lipids. This contributes to the stability of their membranes.

5. **Temperature Stability**:
- The unique structure of these lipids allows Archaebacteria to withstand extreme temperatures. The branched chains help to maintain membrane integrity and prevent leakage under high temperatures.

6. **Membrane Fluidity**:
- The presence of branched chain lipids decreases membrane fluidity, which is advantageous for survival in extreme conditions. This helps maintain the structural integrity of the cell membrane.

7. **Conclusion**:
- Based on the above points, the branched chain lipids in the plasma membrane of Archaebacteria provide decreased membrane fluidity and increased tolerance to extreme heat and pH levels.

### Final Answer:
The branched chain lipids present in the plasma membrane of Archaebacteria contribute to decreased membrane fluidity and increased tolerance to extreme heat and high pH.

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