The plasma membrane is composed of a ____________ layer of phospholipids. The ____________ ends of the phospholipids face the extracellular and intracellular sides. The ____________ ends of the phospholipids face each other and form the core of the membrane. The inner part of the membrane is ____________ . The polar regions of the phospholipids are ____________ . The proteins and phospholipids ____________ move laterally through the membrane.