Describe how a specific gene mutation leads to cystic fibrosis.

A deletion of 3 base pairs occurs on the CFTR gene on chromosome 7, leading to a deletion of the codon coding for phenylalanine at position 508. The loss of phenylalanine disrupts the ATP binding site of the CFTR protein, which prevents binding of ATP and opening of the Cl^- channel, disrupting the diffusion of Cl^- out of the cell.