Which of the following features of phospholipids allows for the phospholipid to interact with the aqueous environment in the extracellular media and the intracellular cytosolic environment?
1. the three-carbon glycenal backbone
2. fatty acids, attached to the three-carbon glycerol backbone of the phospholipid through ester linkages
3. phospholipids do not interact with aqueous environments, such as the extracellular between the cell and the aqueous extracellular and intracellular environments o medium or the cytosolic medium. phospholipids provide a purely hydrophobic barrier
4. the presence of a polar or charged head group attached to the phosphate