Carrier and Channel Proteins

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    • #8270
      vertciel
      Participant

      Hello everyone,

      First post here, and this looks like a great place to be!

      I take Grade 11 Biology. My textbook says that carrier proteins can bring only non-charged substances through the cell membrane, while channel proteins can bring charged substances through the membrane. Unfortunately, it does not explain these two characteristics.

      So my question is: why can’t carrier proteins bring charged substances across the cell membrane?

      Thanks.

    • #76212
      daniel.kurz
      Participant

      Best easy explanation that I can give without getting too detailed is that in channel proteins they have polarity that allows them to be embedded in the cell membrane. This polarity allows molecules that are also polar to slip in. In the case of carrier proteins they bond to nonpolar molecules and have to use active transport of some kind to pull the molecule through the membrane. Look this up online and you should find some stuff.

    • #76222
      mith
      Participant

      Except carrier proteins can also do it without atp…

    • #76253
      MrMistery
      Participant

      carrier protein mechanism:
      1.bind to the substance on one side of the membrane
      2. diffuse to the other side of the membrane
      3. release the substance to the other side

      The speed of this depends on a number of factors: the dissociation constant of the protein, the size of the protein+ligand, the fluidity of the membrane etc

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