Refer to the figure below showing a series of events in a cell. Which statement describes what is happening during the phase labeled 2 in the diagram?
A) Chemical bond energy is expended as a vesicle membrane inserts itself into and fuses with the cell membrane.
B) An enzyme associated with a vesicle opens a hole in the cell membrane, allowing the vesicle to fuse with it.
C) New phospholipids are synthesized at the interface between a vesicle and the cell membrane to allow the two lipid bilayers to fuse.
D) As a vesicle membrane contacts the cell membrane, the lipid bilayers of the two membranes merge to form one interconnected membrane.
E) Enzymes within a vesicle digest part of the vesicle membrane to allow the remaining portion to fuse with the cell membrane.

Question

Refer to the figure below showing a series of events in a cell.  Which statement describes what is happening during the phase labeled 2 in the diagram?
A) Chemical bond energy is expended as a vesicle membrane inserts itself into and fuses with the cell membrane. 
B) An enzyme associated with a vesicle opens a hole in the cell membrane, allowing the vesicle to fuse with it. 
C) New phospholipids are synthesized at the interface between a vesicle and the cell membrane to allow the two lipid bilayers to fuse. 
D) As a vesicle membrane contacts the cell membrane, the lipid bilayers of the two membranes merge to form one interconnected membrane. 
E) Enzymes within a vesicle digest part of the vesicle membrane to allow the remaining portion to fuse with the cell membrane.

Quizplus · Accepted Answer

During phase 2, a vesicle membrane contacts the cell membrane and the lipid bilayers of the two membranes merge to form one interconnected membrane. This process is called membrane fusion and is essential for the transfer of molecules and materials between a vesicle and the cell. Chemical bond energy is expended during this process, but it is not specifically related to the insertion of a vesicle membrane or the digestion of the vesicle membrane. New phospholipids may be synthesized at the interface, but this is not the main mechanism of membrane fusion. An enzyme may be involved in the process, but it does not open a hole in the cell membrane. Therefore, the best choice is D.

Refer to the Figure Below Showing a Series of Events