Question

Transport proteins are required to shuttle polar and charged solutes across cell membranes because the interior of the lipid bilayer is strongly_

Answer 1

Answer: Hydrophobic

Passage through a trans membrane channel protein allows polar and charged compounds to escape the hydrophobic core of the plasma membrane, which would otherwise restrict their entry into the cytoplasm. The phospholipid bilayer consists of two adjacent layers of phospholipids, arranged tail to tail. As phospholipids contain both hydrophilic and hydrophobic regions, they are classed as amphipathic. It consists of a polar phosphate head, which is hydrophilic and a non-polar lipid tail, which is hydrophobic. The structure of the lipid bilayer allows small, uncharged substances and hydrophobic molecules to cross the cell membrane, down their concentration gradient, by simple diffusion.