Which supports the idea that a membrane is asymmetric?
A. the ratio of the area of lipids extracted from red cell membranes to the area of the membranes was 2:1
B. particles were seen in freeze-fractured samples of membranes
C. addition of certain antibodies to cells caused patching of the antigens.
D. Certain proteins can be labeled from either side of a membrane
E. Certain proteins can be labeled from only one side of a membrane.