Ion channels sit in a cell's outer membrane and let electrically charged atoms (ions, as they are known in chemical jargon) in and out of the cell.

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CFTR, as its name suggests, sits in the outer membrane of a cell.

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The best-studied method is for a cell to increase the number of molecular pumps in its outer membrane.

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There is particular concern about Gram-negative bacteria (like E.coli and K. pneumonia), due to their outer membrane which can prevent some antibiotics from penetrating the cell.

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