Question

Explain in detail what happens to the protein when there is a deletion in the DNA for a gene that codes for a chloride channel protein in Cystic Fibrosis. Answers must include the processes of transcription and translation as well as disease characteristics. 12pt Paragraph :

Answer 1

The most common genetic abnormality causing cystic fibrosis involves the deletion of just three DNA bases from the CFTR gene. Cystic fibrosis is a recessive genetic disease which means that both copies of a person's CFTR gene must contain the mutation for cystic fibrosis to occur. The CFTR gene provides instructions for making a protein called the cystic fibrosis transmembrane conductance regulator. This protein channel normally transports chloride ions in and out of these cells which helps control the movement of water in tissues, ensuring that the mucus in the airways and various body systems remains thin and free-flowing. This protein acts as a channel across the membrane of cells that are specialised to produce mucus, sweat, saliva, tears and digestive enzymes.

The most common mutation, called delta F508, is a deletion of one amino acid at position 508 in the CFTR protein. The resulting abnormal channel breaks down shortly after it is made, so it never reaches the cell membrane to transport chloride ions. This means mucus-producing cells secrete mucus that is abnormally thick and sticky resulting in the symptoms of cystic fibrosis.