Cystic Fibrosis Is Caused by a Mutation in the CFTR

Multiple Choice

Cystic fibrosis is caused by a mutation in the CFTR gene. The normal CFTR gene comprises approximately 190,000 nucleotides and produces an mRNA of 6128 nucleotides in length. What is a possible explanation for the difference in the sizes of the gene and the mRNA?

A) The promoter of the CFTR gene is likely silenced by miRNAs prior to mRNA production.
B) The CFTR gene likely has many introns that are excised prior to translation of the CFTR protein.
C) The 5ʹ cap and the poly(A) tail get removed prior to translation of the CFTR protein.
D) Methylation of the 5ʹ cap silences portions of the gene, preventing those regions from being transcribed into mRNA.
E) The mutation that causes cystic fibrosis creates a new terminator sequence, resulting in a shorter mRNA.