Which statement about cystic fibrosis is true?
O who do not have the cystic fibrosis mutation.
Cystic fibrosis is
• caused by a deletion
of one codon in the
DNA molecule.
Cystic fibrosis is caused by a mutation
• in which a dominant allele replaces a recessive allele.
Cystic fibrosis affects a person's ability to make normal red blood cells.
Cystic fibrosis is caused by a mutation in which a dominant allele replaces a recessive allele.
The statement that is true about cystic fibrosis is that it is caused by a mutation in which a dominant allele replaces a recessive allele.
The correct statement about cystic fibrosis is: Cystic fibrosis is caused by a mutation in which a recessive allele is inherited from both parents.
To understand this, we need to start with some background information. Cystic fibrosis (CF) is a genetic disorder that affects the production and function of certain secretory glands in the body. It is caused by mutations in the cystic fibrosis transmembrane conductance regulator (CFTR) gene.
Now let's break down the options provided:
1. "O who do not have the cystic fibrosis mutation." - This statement doesn't provide any information about cystic fibrosis. It simply refers to individuals who do not have the mutation, which is not an accurate statement about the condition itself.
2. "Cystic fibrosis is caused by a deletion of one codon in the DNA molecule." - This statement is incorrect. While there are many different mutations that can contribute to cystic fibrosis, it is not caused by a single deletion of one codon. Mutations in the CFTR gene may involve deletions, insertions, or substitutions of multiple nucleotides.
3. "Cystic fibrosis is caused by a mutation in which a dominant allele replaces a recessive allele." - This statement is also incorrect. Cystic fibrosis is an autosomal recessive disorder, which means that both copies of the CFTR gene need to carry the mutation for an individual to have the condition. In other words, a recessive allele must be inherited from both parents.
4. "Cystic fibrosis affects a person's ability to make normal red blood cells." - This statement is incorrect. Cystic fibrosis primarily affects the respiratory, digestive, and reproductive systems. It causes the production of thick, sticky mucus, which can lead to a range of symptoms and complications.
Therefore, the third statement, which states that cystic fibrosis is caused by a mutation in which a recessive allele replaces a recessive allele, is the correct statement.