Question

The mutations found in the CF gene that result in cystic fibrosis are recessive because

- dominant alleles that cause a fatal disorder, such as cystic fibrosis, cannot be inherited.
- the CF mutations always result in no protein being produced
- CF mutations result in a protein that has normal function only if normal protein also exists in the cell
- the protein produced by the normal allele is sufficient for normal cellular function.

Answer 1

The CF gene mutations that cause cystic fibrosis are recessive because one normal allele can produce enough functional protein for normal cellular function, preventing the expression of the disease in carriers.

Step-by-step explanation:

The mutations found in the CF gene that result in cystic fibrosis are recessive because a single normal allele can produce enough functional protein to maintain normal cellular function. Carriers of cystic fibrosis have one copy of the normal CFTR gene and one mutated gene, but do not express the symptoms of cystic fibrosis since the protein produced by the normal allele is sufficient.

A person must inherit two copies of the recessive mutant CFTR gene to express the disease, which makes the disorder recessive to the normal phenotype. In order for a disease to be recessive, both copies of the gene must be mutated. If a person has one normal copy of the gene and one mutated copy, they will still produce enough of the functioning protein to avoid the signs and symptoms of cystic fibrosis.