Lipids, mainly phospholipids, make up the bulk of the cell membrane. How is the structure of the phospholipid so perfectly paired to the function of the cell membrane? A) Phospholipids are bulky/large molecules that prevent all molecules from entering/exiting the cell. B) The polar tails of the phospholipids provide the barrier between the exterior/interior hydrophilic environments. C) Lipids contain high energy bonds, and these bonds help to provide the energy to move molecules across the membrane. D) The head of the phospholipid, which is hydrophilic, helps to control the movement of large hydrophobic molecules, and the tails of the phospholipid, which are hydrophobic, help to control the movement of large hydrophilic molecules.
D) The head of the phospholipid, which is hydrophilic, helps to control the movement of large hydrophobic molecules, and the tails of the phospholipid, which are hydrophobic, help to control the movement of large hydrophilic molecules.
Explanation:
Phospholipids are lipids composed of a glycerol molecule, an unsaturated fatty acid chain and a saturated chain, one or two phosphate groups and a polar molecule attached thereto. Phospholipids are amphipathic molecules, ie they have part of the molecule that is hydrophilic and the other part that is hydrophobic: They have a head consisting of the phosphate (polar) group attached to a tail consisting of fatty (apolar) fatty acid chains. In the cell membrane the polar heads are facing outwards and the apolar tails inwards. The phospholipid head, which is hydrophilic, helps control the movement of large hydrophobic molecules, and the phospholipid tails, which are hydrophobic, help control the movement of large hydrophilic molecules.
