Question

The most abundant phospholipid in E.coli plasma membrane is

• A. phosphatidyl ethanolamine
• B. phosphatidyl choline
• C. phosphatidyl serine
• D. phosphatidyl inositol

Hint:

Remember that phosphatidyl ethanolamine is the major phospholipid in most bacterial membranes, whereas phosphatidyl choline is dominant in many eukaryotic membranes.

Answer 1

The Correct Option is A

Step 1: Understand the plasma membrane composition of E.coli.
The plasma membrane of E.coli mainly consists of phospholipids and proteins. Different phospholipids are present in different proportions depending on their structural and functional roles.

Step 2: Identify the major phospholipid present in bacteria.
In most bacterial membranes, especially in E.coli, phosphatidyl ethanolamine is the dominant phospholipid component. It contributes significantly to membrane stability and fluidity.

Step 3: Analyze option (A).
Phosphatidyl ethanolamine constitutes nearly \(70\%-80\%\) of the total phospholipid content in the E.coli plasma membrane. Hence, this option is correct.

Step 4: Analyze option (B).
Phosphatidyl choline is abundant in eukaryotic membranes but is generally absent or present in very low amounts in E.coli. Therefore, this option is incorrect.

Step 5: Analyze option (C).
Phosphatidyl serine is only a minor intermediate in phospholipid biosynthesis in bacteria and is not the major membrane phospholipid. Hence, this option is incorrect.

Step 6: Analyze option (D).
Phosphatidyl inositol is commonly found in eukaryotic cells and some specialized bacteria, but not as the major phospholipid in E.coli. Thus, this option is incorrect.

Step 7: Final conclusion.
Therefore, the most abundant phospholipid in the plasma membrane of E.coli is phosphatidyl ethanolamine.
\[ \boxed{\text{phosphatidyl ethanolamine}} \]
Hence, the correct answer is option (A).