Question

In eukaryotic cells, new phospholipids are manufactured byenzymes bound

to which part of the endoplasmic reticulum membrane?
A. The monolayer that faces the lumen of the endoplasmic reticulum
B. The monolayer that faces the cytosol
C. Both monolayers

Answer 1

New phospholipids in eukaryotic cells are synthesized by enzymes bound to the monolayer of the endoplasmic reticulum that faces the cytosol.

Step-by-step explanation:

In eukaryotic cells, new phospholipids are synthesized by enzymes that are bound to the monolayer that faces the cytosol of the endoplasmic reticulum membrane. This is because the synthesis of phospholipids involves several enzymes that work on the cytoplasmic side of the ER to facilitate the creation of the new phospholipids, which are then distributed between the two layers of the bilayer. The phosphate groups of phospholipids are hydrophilic and face the aqueous environments inside and outside the cell, while the hydrophobic fatty acid tails face the interior of the membrane, excluding water from this space. During phospholipid synthesis, the molecules first insert into the cytosolic layer and are eventually distributed evenly between both layers of the bilayer.