Genetic Mutations Exercise
Instructions: Below you are given an imaginary wildtype sense strand (coding strand) of DNA and the corresponding mature mRNA sequence with its corresponding protein sequence. Five mutant DNA sense strands are presented. For each mutant DNA strand (mutant 2-5), write the mRNA strand, the protein sequence, and an explanation of the type(s) of mutation represented, including the impact on protein synthesis.
Wildtype sense strand sequence: ATG-TCA-CCC-GCG-CAG-GAA-GGA
(Upper case letters denote coding sequence of the DNA)
Mature mRNA sequence: AUG-UCA-CCC-GCG-CAG-GAA-GGA
Protein sequence: methionine-serine-proline-alanine-glutamine-glutamic acid-glycine
Mutant 1: ATG-TGA-CCC-GCG-CAG-GAA-GGA
mRNA: AUG-UGA-CCC-GCG-CAG-GAA-GGA
Protein: methionine-stop
Mutation: The fifth base is changed from a C to a G. This is a point mutation (and a base substitution). The mutation causes a nonsense mutation because a codon for serine is replaced by a stop codon, resulting in a truncated protein.
Mutant 2: ATG-TCA-ACC-GCG-CAG-GAA-GGA
mRNA: AUG-UCA-ACC-GCG-CAG-GAA-GGA
Protein: Methionine-Serine-Threonine-Alanine-Glutamine-Glutamic acid-Glycine
Mutation:
Mutant 3: ATG-CAT-TCA-CCC-GCG-CAG-GAA-GGA
mRNA: AUG-CAT-UCA-CCC-GCG-CAG-GAA-GGA
Protein: Methionine-
Mutation: