ead instructions 4-6 before you begin and think about the relationships between
ID: 91039 • Letter: E
Question
ead instructions 4-6 before you begin and think about the relationships between
the various steps!
Cystic fibrosis is a life threatening genetic disease cause by mutation in a
gene called CFTR.CFTR encodes a transmembrane protein pictured below. It is
in the plasma membrane and is a transporter for chloride and thiocyanate
ions. People with cystic fibrosis have a mutation in this gene which renders
CFTR nonfunctional. This creates a thick mucus in the lungs and patients are
prone to bacterial infections. This leads to a life expectancy of roughly 40
years.
Below is part of the CFTR gene. Use it to answer the following questions.
5’-gagtagtagg tctttggcat taggagcttg agcccagacg gccctagc 3’
4. Suppose you find a frameshift mutation. Write what this would look like in the sequence and
how it changes the protein. Why would it affect function?
5. Suppose you find a missense mutation. Write what this would look like in the sequence and how
it changes the function of the protein.
6. Suppose that you don’t find a silent mutation above. Propose a hypothesis for how the silent
mutation is causing a the disease.
NH2 MSD1 00000000 T T BD1 MSD2 BD COOHExplanation / Answer
4. The frame shift mutation will lead to different protein composition due to change in the reading frame of the sequence. In the provided sequence if the first two nucleotides ga is deleted in the 5' end then the entire reading frame of the protein will be altered. The codons will be GTA GTA instead of GAG TAG TA. etc.
5. In missense mutation it is a single nucleotide change which results in a codon that codes for a different amino acid. It is a type of non synonymous substitution. Only one amino acid in the protein will be altered, it might or mightn't alter the function of the protein based on the region of location.
6. Silent mutation does not alter the phenotype of the protein, it might also occur in the non coding region.
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