Cystic fibrosis is a recessively inherited disorder that results from a mutation in the gene encoding CFTR chlorine ion channels located on the surface of many epithelial cells. As shown in the figure, the mutation prevents the normal movement of chloride ions from the cytosol of the cell to the extracellular fluid. As a consequence of the mutation, the mucus layer that is normally present on the surface of cells becomes exceptionally dehydrated and viscous. An answer to which of the following questions would provide the most information about the association between the CFTR mutation and the viscous mucus?
A) Is the mucus also secreted from the cells through the CFTR proteins?
B) How does the disrupted chloride movement affect the movement of sodium ions and water by the cell?
C) How does the mutation alter the structure of CFTR proteins?
D) What is the change in nucleotide sequence that results in the CFTR mutation?
Ans: B) How does the disrupted chloride movement affect the movement of sodium ions and water by the cell?
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