Fig. 5.31  For organelles enclosed in two phospholipid membranes (e.g., nucleus, chloroplast, mitochondrion), the cytosolic always faces the cytoplasm.

Fig. 5.35  Experimental demonstration that cell-surface proteins are laterally mobile.

Fig. 5.37  Alternative forms of the phospholipid bilayer is dependent on temperature.

Movie on membrane gradients, energy potentials and transport.