Question

Archaeal cell membranes contain lipids that are

• A. Ether linked
• B. Ester linked
• C. Branched alkyl chain
• D. Linear alkyl chain

Answer 1

The Correct Option is A, C

To answer the question correctly, we need to understand the unique characteristics of archaeal cell membranes compared to those of bacteria and eukaryotes.

Archaeal cell membranes are noteworthy for two main features:

1. Ether-linked lipids: Unlike bacteria and eukaryotes, which have ester-linked fatty acids in their phospholipids, archaea have ether linkages. These ether bonds occur between the glycerol backbone and the isoprenoid chains. The stability offered by ether bonds is advantageous because it allows archaea to survive in extreme environments, often with high temperatures or harsh chemical conditions.
2. Branched alkyl chains: The lipids in archaeal membranes often have branched isoprenoid chains rather than the linear chains found in bacterial and eukaryotic membranes. These branched chains lead to more compact and less permeable membranes, increasing resistance to extreme environmental conditions, such as high salinity and temperature.

Now, let's evaluate the given options:

• Ether linked:
  This is correct as archaeal membrane lipids feature ether bonds.
• Ester linked:
  This option refers to bacterial and eukaryotic membranes, not archaeal.
• Branched alkyl chain:
  This is correct, as archaeal lipids have branched isoprenoid chains.
• Linear alkyl chain:
  This is incorrect for archaea, but characteristic of bacterial and eukaryotic membranes.

Hence, the correct characteristics of archaeal cell membrane lipids are:

• Ether linked
• Branched alkyl chain

These adaptations contribute to the ability of archaea to thrive in extreme environments, distinguishing them from bacteria and eukaryotes.