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

Question

Responses

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

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

Answer 1

The statement that is true about cystic fibrosis is:

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

This statement refers to the "heterozygote advantage," where carriers (those with one copy of the cystic fibrosis allele and one normal allele) may have some increased resistance to certain diseases, such as tuberculosis.

The other statements are incorrect:

• Cystic fibrosis is caused by a mutation in the CFTR gene, which is a recessive disorder, not a dominant-recessive replacement.
• The mutation that typically leads to cystic fibrosis is a deletion of three nucleotides (not one codon), resulting in the loss of the amino acid phenylalanine in the CFTR protein.
• Cystic fibrosis primarily affects the respiratory and digestive systems, not the ability to make normal red blood cells.