1. Consider the following DNA sequence found on a different portion the coding strand of Henry's CYP2C9 gene: TTACCGAGA
a. What would be the sequence of the template strand on this portion of the gene?
b. How many triplet codes does this DNA sequence contain?
c. What would be the sequence of the mRNA after this sequence is transcribed?
d. How many amino acids does this portion of Henry''s coding stand actually code for?
2. In the first mutation of the CYP2C9 gene described in Henry''s story, the 1075th nucleotide had changed from an adenine (A) to a cytosine (C). This mutation converts an ATT triplet code in the coding strand of the DNA molecule to CTT. Beginning with this triplet code on the DNA, describe the effect that this change would have on the following:
a. The nucleotide sequence on the template strand of the gene.
b. The mRNA codon that results after this triplet code is transcribed.
c. The anticodon on the tRNA molecule that is complementary to the mRNA codon described above.
d. The amino acid that would be carried by the tRNA molecule described above.
3. In Henry's other CYP2C9 gene, the 430th nucleotide had changed from a cytosine (C) to a thymine (T). This mutation converts a CGT triplet code in the coding strand of the DNA molecule to TGT. Beginning with this triplet code on the DNA, describe the effect that this change would have on the following:
a. The nucleotide sequence on the template strand of the gene.
b. The mRNA codon that results after this triplet code is transcribed.
c. The anticodon on the tRNA molecule that is complementary to the mRNA codon described above.
d. The amino acid that would be carried by the tRNA molecule described above.
4. From what you understand about enzymes, explain why a change in an amino acid would cause Harry''s enzyme to lose its function.
5. In both of Henry''s mutations, it is the first nucleotide in the DNA triplet code that has been changed.
a. Using the genetic code chart below, create a list of single nucleotide changes in the two affected triplet codes described for Henry''s genes that could occur WITHOUT resulting in a change in the amino acid in the enzyme.
NOTE: The code chart below contains mRNA codons and the amino acids associated with those codons. Your list should contain DNA triplet codes.
b. How many triplet code changes did you find that could occur WITHOUT resulting in an amino acid change in the enzyme?
c. Which position (first, second, or third) did the changes occur within the DNA triplet codes you listed above?
d. What would you conclude from the pattern that emerged?