Recall why water-soluble molecules and ions have difficulty crossing a lipid bilayer.
ions are least permeable. Only transported through channel or transporter Water soluble molecules are semi permeable. Hydrophobic molecules are most permeable (i.e O2, CO2, N2)
Water-soluble molecules and ions have difficulty crossing a lipid bilayer because the interior of the bilayer is hydrophobic, meaning it repels water. As a result, water-soluble molecules and ions cannot easily pass through the hydrophobic core of the bilayer, which is made up of nonpolar fatty acid chains. This means that they are generally unable to diffuse through the bilayer and require transport proteins or specialized channels to move across the membrane.
More Answers:
Differences between Membrane Transport Proteins: Transporters vs. ChannelsOptimizing Solute Diffusion: Properties Governing Lipid Bilayer Permeability
Passive Transport: Simple Diffusion vs Facilitated Transport Mechanisms
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