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: What the question wants.
We need the phospholipid that makes up the biggest share of the E. coli cell membrane.

Step 2: Recall the lipid make-up of a bacterial membrane.
Bacterial membranes run on just a few lipid types. In gram negative bacteria like E. coli, one neutral lipid dominates while the others sit at small levels.

Step 3: Point to the main one.
That dominant lipid is phosphatidyl ethanolamine. It alone covers most of the membrane, roughly three quarters of the total lipid.

Step 4: Rule out the choline, serine and inositol forms.
Phosphatidyl choline and phosphatidyl inositol are typical of animal and plant cells, not of E. coli. Phosphatidyl serine shows up only briefly as a building block on the way to making the ethanolamine form, so its standing amount stays tiny.

Step 5: Answer.
So the winner is phosphatidyl ethanolamine. \[ \boxed{\text{phosphatidyl ethanolamine}} \]