Mutations Worksheet
Remember, each strand of DNA must be transcribed into its mRNA transcript. You may use T rather than U for ease, but remember that in the cell, mRNA uses uracil to bond with adenine. Use the genetic code to determine your answers.
Since the code is degenerate, it tolerates some mutations. For the following, identify the start codon, and then number the codons with number one being the first after the start codon. With each question you will be given some background. Identify each example under each question as either normal, or give the codon number with a mutation, and the amino acid this mutation codes for.
1. A base-pair substitution is the replacement of a nucleotide pair with another. This can either cause a change in the protein, or it may not due to the degeneracy of the code. The following is the sequence of amino acids in a protein. Which of the following strands of DNA would code for this protein? If it can not, identify the mutation, and the consequent amino acid.
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Lys = Phe = Gly = Ala = Leu = Stop
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a. A T A T T A C T T C A A A C C G C G T A A C A T T
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b. A T A T T A C T T T A A A C C A C G T A A C A T T
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c. A T A T T A C T T C A A A T C G C G T A A C A T T
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d. A T A T T A C A T C A A A C C G C G T A A C A T T
2. You are a genetic counselor, and just received the results back from the DNA testing you sent out for. Two weeks ago you obtained blood samples from five members of a family that wanted to know if they had sickle-cell anemia. They all exhibit some form of anemia, but they want to know if it is sickle-cell to determine if they will pass it on to their future children. From the blood samples they isolated the gene that codes for the production of hemoglobin. Normal hemoglobin differs from sickle-cell hemoglobin in that valine is inserted into the protein where glutamic acid should be. This difference cause the cells to change shape, resembling crescent moons or sickles, and render them incapable of carrying oxygen. Which of the following samples have a mutation that causes the sickle-cell anemia disorder?
normal hemoglobin: Val = His = Leu = Thr = Pro = Glu = Glu = Lys ....
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a. T A C C A T G T G A A T T G G G G T C T C C T T T T T
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b. T A C C A A G T A G A A T G A G G C C T T C T C T T C
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c. T A C C A A G T A G A A T G A G G C C A A C T C T T C
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d. T A C C A A G T A G A A T G A G G C C A T C T T T T C
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e. T A C C A C G T G A A T T G G G G T C T C C T T T T T
