Question

the high permeability of the membrane to hexanoic acid is quite unusual given that hexanoic acid is larger than water and carries a negative charge like cl, which crosses the membrane so slowly that it is almost impossible for it to actually happen in a living cell. what other property or properties does hexanoic acid have that make it possible for this molecule to quickly cross a cell membrane? select all that apply. negatively charged ions cross the cell membrane more easily than positively charged ions. the tail of hexanoic acid and the phospholipid tails in the cell membrane are both hydrophobic. hexanoic acid is saturated and therefore linear so it will move through the membrane more easily than acetic acid. the shorter tail of acetic acid compared to hexanoic acid makes acetic acid more polar than hexanoic acid

Explanation:

• Option 1: There is no general rule that negatively - charged ions cross the membrane more easily than positively - charged ions. Ion permeability depends on many factors like ion channels and transporters, not just charge sign.
• Option 2: The cell membrane has a phospholipid bilayer with hydrophobic tails. Hexanoic acid has a hydrophobic tail. Hydrophobic interactions allow it to dissolve in the hydrophobic core of the membrane, facilitating its passage.
• Option 3: While hexanoic acid is saturated and linear, this is not the main reason for its permeability compared to the hydrophobic nature. Acetic acid has a shorter carbon chain, but the key is the hydrophobicity of hexanoic acid's tail.
• Option 4: Acetic acid has a shorter tail (\(CH_3COOH\)) compared to hexanoic acid (\(CH_3(CH_2)_4COOH\)). A shorter tail makes acetic acid more polar (less of a hydrophobic tail to counteract the polar - COOH group). Since the membrane has a hydrophobic core, less polar (more hydrophobic) molecules like hexanoic acid can pass more easily.

Answer:

B. The tail of hexanoic acid and the phospholipid tails in the cell membrane are both hydrophobic.
D. The shorter tail of acetic acid compared to hexanoic acid makes acetic acid more polar than hexanoic acid.