NUTRITION
LIPIDS
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Question
[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
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Small, uncharged polar molecules.
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Small, nonpolar molecules.
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Large, unchaged polar molecules.
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Ions.
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Detailed explanation-1: -Size and polarity affect the permeability of molecules through the phospholipid bilayer. The lipid bilayer has a largely non-polar interior, therefore, non-polar molecules are more permeable than polar molecules. The smaller the molecule, the easier it can cross the membrane.
Detailed explanation-2: -It may also be said that membrane permeability is high for lipid-soluble molecules, and that membrane permeability is low for ions and polar molecules. Another way of stating this is that lipid-soluble molecules are highly permeant, or that ions are impermeant (i.e., not permeant).
Detailed explanation-3: -Small polar molecules can sometimes pass easily (e.g. ethanol), but more often pass at low rates if at all (e.g. water). However, small nonpolar molecules are able to pass through the membrane with relative ease.