Question

cystic fibrosis is a rare, inherited disease caused by a genetic mutation. this disease causes mucus - producing cells to make abnormally thick and sticky mucus which can clog airways, glands, and portions of the digestive tract. cystic fibrosis is caused by a mutation in the cftr gene as shown below.
original dna: ggt ctt act cca
mutated dna: ggt act cca
what type mutation leads to cystic fibrosis?
a insertion
b substitution
c deletion
d inversion

Explanation:

• Insertion: Adds nucleotides. Not here.
• Substitution: Replaces nucleotides. Not the case.
• Deletion: Removes nucleotides. Original has 4 triplets, mutated has 3. One (CTT) is deleted.
• Inversion: Reverses nucleotide order. Not applicable.

Answer:

C. Deletion