Final answer:
Cystic fibrosis is caused by a defective ion channel called CFTR that transports chloride ions out of the cell. In people with CF, the mutated gene produces a defective CFTR protein, resulting in abnormal fluid secretions and characteristic symptoms.
Step-by-step explanation:
Cystic fibrosis (CF) is caused by a defective ion channel called the cystic fibrosis transmembrane conductance regulator (CFTR). In healthy individuals, the CFTR protein transports chloride ions (Cl-) out of the cell, helping to maintain fluid balance. However, in people with CF, the gene responsible for producing CFTR is mutated, resulting in a defective channel protein that is not properly incorporated into the cell membrane. This leads to abnormal fluid secretions and the characteristic symptoms of CF.