Question

Which statement about cystic fibrosis is true?(1 point)
Responses

Cystic fibrosis affects a person’s ability to make normal red blood cells.
Cystic fibrosis affects a person’s ability to make normal red blood cells.

Cystic fibrosis is caused by a deletion of one codon in the DNA molecule.
Cystic fibrosis is caused by a deletion of one codon in the DNA molecule.

Carriers have an advantage over people who do not have the cystic fibrosis mutation.
Carriers have an advantage over people who do not have the cystic fibrosis mutation.

Cystic fibrosis is caused by a mutation in which a dominant allele replaces a recessive allele.

Answer 1

Among the statements provided, the following is true:

**Carriers have an advantage over people who do not have the cystic fibrosis mutation.**

This statement refers to the idea that carriers of the cystic fibrosis allele may have some advantages regarding resistance to certain diseases, such as typhoid fever or possibly other infections, although it's important to note the specific advantages can vary based on environmental and other factors.

The other statements are inaccurate for the following reasons:

1. Cystic fibrosis primarily affects the respiratory and digestive systems due to mutations in the CFTR gene, not red blood cell production.

2. Cystic fibrosis is caused by a mutation in a single codon in the DNA sequence (specifically a deletion of three nucleotides leading to the loss of a phenylalanine amino acid at position 508), but it should be noted that this is not simply a deletion of one codon as stated.

3. Cystic fibrosis is inherited in an autosomal recessive manner, meaning both copies of the CFTR gene must be mutated for the disease to manifest; it does not involve a dominant allele replacing a recessive one.