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Why are membrane more permeable to non-polar molecules than to most polar and ionized molecules?
Wiki User
∙ 14y ago
Because the permeation through a membrane depends on the diffusivity (size of the permeate molecules) and the solubility (briefly the interaction equilibrium) of the permeate in the membrane. Considering permeate mixtures, membranes can be size-selective and sorption-selective depending on which relative term (ratio of diffusivities or ratio of solubilities) dominates. Most known membrane separation processes involve size-selectivity, i.e., the "smaller" the permeate molecule, the faster it gets through the membrane. More sophisticated membrane separation processes are sorption selective, where it is possible that the "bigger" molecules exhibit a higher permeation flux than the "smaller" ones.
Wiki User
∙ 13y ago
Wiki User
∙ 11y agoit's simply because the lipid bi layer is nonpolar, and like substances dissolve other like substances. polar molecules don't interact with non-polar and that is why the cell membrane does not allow polar molecules to diffuse right through.
Wiki User
∙ 14y agob/c the cell membrane is made out of phospholipids! thus lipis diffuse readily
Wiki User
∙ 12y agoBecause the membranes are made up of phospholipid bilayers
Wiki User
∙ 14y agoNon-polar molecules are generally smaller than polar and ionized ones. The non-polar tails of the phospholipids repel ionic molecules and don't allow them to pass.
Wiki User
∙ 14y agoBecause the phospholipids of the plasma membrane are lipid, and a lipid soluable such as cholesterols can pass through the membrane.
Wiki User
∙ 10y agoparce que c'est dommage
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Are ionized molecules less reactive than non-ionized molecules?
yes
Are Ions charged atoms or groups of atoms?
Either one. You can have an ionized atom or an ionized molecule. Many ionized molecules are radicals that had been part of a larger molecule and the event that separated them also ionized the radical. This is what free radicalsare.
How would you build a model that is ionized?
When the number of electrons does not equal the number of protons, the atom is ionized. (The atom is then called an ion).
The fraction of acetic acid molecules ionized in solution?
Less than 0.5% of acetic acid ionizes
Why do mole drug molecules have both water-soluble and oil-soluble functional groups?
The drug has to be water soluble to dissolve as gastrointestinal fluid is aqueous. The drug also has to be oil soluble as only the lipid soluble non-ionized form can readily diffuse across the lipid membrane.
What molecules can pass phospholipid bilayer?
Non ionized molecule pass through the lipid bilayer faster than ionized molecules because of the hydrophobic portion of the lipid bilayer. non ionized molecules are ex glucose ionized molecute Na, K
Are ionized molecules less reactive than non-ionized molecules?
yes
Do water molecules ionize when they freeze?
No, the ice molecules in ice are not ionized.
Are Ions charged atoms or groups of atoms?
Either one. You can have an ionized atom or an ionized molecule. Many ionized molecules are radicals that had been part of a larger molecule and the event that separated them also ionized the radical. This is what free radicalsare.
How would you build a model that is ionized?
When the number of electrons does not equal the number of protons, the atom is ionized. (The atom is then called an ion).
Is a distilled water a polar or nonpolar?
Ionized water means that there are ions in a solution of water. Water itself, whether alone or floating with ions, will always be polar. Other ions or molecules don't affect water's polarity without changing the compound, in which case it will no longer be water.
Molecules are spaced farthest apart in?
Molecules are, in general, farthest apart from one another in the gas phase.
The fraction of acetic acid molecules ionized in solution?
Less than 0.5% of acetic acid ionizes
What is an autoionization?
An autoion is an ion which has been formed via the process of autoionization - where atoms or molecules spontaneously transition from an electrically neutral state to a lower-energy ionized state.
Why do mole drug molecules have both water-soluble and oil-soluble functional groups?
The drug has to be water soluble to dissolve as gastrointestinal fluid is aqueous. The drug also has to be oil soluble as only the lipid soluble non-ionized form can readily diffuse across the lipid membrane.
What substance can pass through the lipid bilayer i.e. in between the phospholipid molecules?
Lipid solublewater insolublenon-polarnon-ionized
Why are drugs in solid form unlikely to be absorbed in the stomach to any significant extent?
Only the lipid soluble non-ionized form of a drug can diffuse across the membrane. The pH is low in the stomach. For the acidic drugs, they are non-ionized at low pH yet they are poorly soluble. For the basic drugs, they are soluble yet ionized.
