poler molecules and ions?

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    • #1309
      Decker
      Participant

      why cant most polar molecules and ions enter cells? But also alot of food particles are polar, so how do they get in the cell?

      (sorry if this is the wrong forum)

      Thanks Everyone.

    • #25686
      mith
      Participant

      The membrane of the cell is made of phospholipid bilayer.
      There are proteins which go thru the membrane.

    • #25687
      James
      Participant

      Channel and carrier proteins get around the problem.

    • #25688
      Decker
      Participant
      quote mithrilhack:

      The membrane of the cell is made of phospholipid bilayer.
      There are proteins which go thru the membrane.

      could you please explain this further, are you saying that the polar molecules and ions cant enter because the membrane keeps them out? i belive that is what you are saying, if so how do the food particles get through.

    • #25689
      mith
      Participant

      Think of it this way:

      The membrane is a chain-linked fence. Only really small molecules can pass thru while big molecules can’t. To remedy this, the fence has special passages(gates) that allow bigger stuff in(see James’s post).

    • #25698
      biostudent84
      Participant

      Many ions are smaller than water molecules. And water can definetly get through the membrane.

      Ions cannot diffuse through the membrane because overall, the membrane is nonpolar. Ions are repelled away from the membrane.

    • #25786
      chemistry_freako
      Participant

      Yeap – the outer layer is hydrophilic (water- loving) due to the phosphate groups, but the inner layer is where the hydrophobic (water- hating) ‘lipid tails’ are =D

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