A human gene called theCFTR gene (for cystic fibrosis transmembrane regulator) encodes aprotein that functions in the transport of chloride ions across the cellmembrane. Most people have two copies of a functional CFTR geneand do not have cystic fibrosis. However, a mutant version of the CFTRgene is found in some people. If a person has two mutant copies ofthe gene, he or she develops the disease known as cystic fibrosis. Arethe following descriptions of this disease related to genetics at themolecular, cellular, organism, or population level?A. People with cystic fibrosis have lung problems due to a buildupof thick mucus in their lungs.B. The mutant CFTR gene encodes a defective chloride transporter.C. A defect in the chloride transporter causes a salt imbalance inlung cells.D. Scientists have wondered why the mutant CFTR gene is relativelycommon. In fact, it is the most common mutant gene that causesa severe disease in persons of Northern European descent. Onepossible explanation why cystic fibrosis is so common is thatpeople who have one copy of the functional CFTR gene and onecopy of the mutant gene may be more resistant to diarrheal diseases such as cholera. Therefore, even though individuals withtwo mutant copies are very sick, people with one mutant copyand one functional copy might have a survival advantage overpeople with two functional copies of the gene.
A human gene called the
CFTR gene (for cystic fibrosis transmembrane regulator) encodes a
protein that functions in the transport of chloride ions across the cell
membrane. Most people have two copies of a functional CFTR gene
and do not have cystic fibrosis. However, a mutant version of the CFTR
gene is found in some people. If a person has two mutant copies of
the gene, he or she develops the disease known as cystic fibrosis. Are
the following descriptions of this disease related to genetics at the
molecular, cellular, organism, or population level?
A. People with cystic fibrosis have lung problems due to a buildup
of thick mucus in their lungs.
B. The mutant CFTR gene encodes a defective chloride transporter.
C. A defect in the chloride transporter causes a salt imbalance in
lung cells.
D. Scientists have wondered why the mutant CFTR gene is relatively
common. In fact, it is the most common mutant gene that causes
a severe disease in persons of Northern European descent. One
possible explanation why cystic fibrosis is so common is that
people who have one copy of the functional CFTR gene and one
copy of the mutant gene may be more resistant to diarrheal diseases such as cholera. Therefore, even though individuals with
two mutant copies are very sick, people with one mutant copy
and one functional copy might have a survival advantage over
people with two functional copies of the gene.
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