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Maggie’s Illness

Protein Structure and Function in Cystic Fibrosis


Michaela Gazdik Stofer
Department of Biology
Utah Valley University


This directed case study examines the molecular basis of cystic fibrosis to emphasize the relationship between the genetic code stored in a DNA sequence and the encoded protein’s structure and function. Cystic fibrosis is caused by mutations in the cystic fibrosis transmembrane conductance regulator (CFTR) protein that functions to help maintain salt and water balance along the surface of the lung and gastrointestinal tract. This case introduces students to “Maggie,” who has just been diagnosed with cystic fibrosis. The students must identify the mutation causing Maggie’s disease by transcribing and translating a portion of the wildtype and mutated CFTR gene. Students then compare the three-dimensional structures of the resulting proteins to better understand the effect a single amino acid mutation can have on the overall shape of a protein. Students also review the concepts of tonicity and osmosis to examine how the defective CFTR protein leads to an increase in the viscosity of mucus in cystic fibrosis patients. This case was developed for use in an introductory college-level biology course but could also be adapted for use in an upper-level cell or molecular biology course.


  • Generate a protein sequence through transcription and translation of a given DNA gene sequence.
  • Explain the chemistry of amino acid side chains and their importance in protein folding.
  • Describe how a mutation in a protein sequence leads to changes in the overall tertiary structure of the protein.
  • Examine various levels of protein structure using Cn3D to view three-dimensional protein structures from NCBI’s Entrez Structure database.
  • Relate the loss of function of the CFTR protein to the physiological causes of cystic fibrosis.


Protein structure; transcription; translation; DNA mutation; cystic fibrosis; genetic disease; protein function; protein folding; protein; CFTR; Cn3D

Topical Areas


Educational Level

Undergraduate lower division, Undergraduate upper division



Type / Methods




Subject Headings

Biology (General)  |   Biotechnology  |   Cell Biology  |   Molecular Biology  |  

Date Posted


Teaching Notes

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Supplemental Materials

The following two files should be viewed with the Cn3D software to view a single domain of the CFTR and ∆F508 CFTR proteins.

  ∆F508 CFTR

Answer Key

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