A mixed solution of water and small molecules is exposed to a cell membrane and allowed to interact for an hour.Which molecule would be most likely to cross the phospholipid bilayer without the aid of transport proteins and diffuse across the membrane the fastest? A)Estrogen (C₁₈H₂₄O₂) B)NH₄⁺ C)O₂ D)CH₃COO^- E)Na⁺

Question

Quizplus · Accepted Answer

The molecule with the simplest structure (fewest functional groups) and smallest size will be most likely to cross the phospholipid bilayer without the aid of transport proteins and diffuse across the membrane the fastest. Option C, which is a simple molecule with only one functional group, fits this description best. The other options are either too large (option A and D) or too charged (option B and E), which will make it difficult for them to move across the nonpolar interior of the phospholipid bilayer.

A Mixed Solution of Water and Small Molecules Is Exposed