Two experiments are carried out simultaneously. In the first experiment, a flask containing phospholipids, water, and glycine is sonicated to form liposomes. The liposomes are separated by dialysis to remove glycine that is not trapped in the liposomes and resuspended in a flask of water. In the second experiment, the same steps are carried out except that alanine is used instead of glycine. In both cases, it was verified that the liposomes took up significant amounts of the respective amino acids. After several hours, small aliquots of the water are removed (avoiding any liposomes) and the concentration of alanine and glycine is measured. The first flask contains a concentration of glycine that is 3% of the initial concentration, while the second flask contains no alanine. What conclusions can be drawn