HOW DO GENE MUTATIONS AFFECT PROTEINS?
Gene mutations often have serious effects on proteins. In this activity, you will
demonstrate how such mutations affect Protein Synthesis.
Use the following DNA strand to complete the activity.
AATGCCAGTGGTTCGCAC
1. Write the sequence of the complementary mRNA strand formed during transcription.
2. Using the amino acid chart (see notes), determine the order of amino acids in the
resulting protein.
Change 1
3. Now, change the fourth nucleotide in the DNA strand from G to C and write out the
new DNA strand.
4. Write the sequence of the complementary mRNA strand formed from the mutated
DNA during Transcription.
5. Using the amino acid chart (see notes), determine the new order of amino acids in
the resulting protein.
Change 2
6. Now, add a G to the original DNA strand (top) after the third base and write out the
new DNA strand.
7. Write the sequence of the complementary mRNA strand formed from the mutated
during Transcription.
8. Using the amino acid chart (see notes), determine the new order of amino acids in
the resulting protein fragment.
Analysis
9. A point mutation substitutes on DNA base for another, for example an A is switched
to a G. Which change in DNA was a point mutation? In what way did the point mutation
change the protein?
10. A frameshift mutation occurs when a DNA base is either added or removed. This
“shifts” the reading frame. Which change in DNA was a frameshift mutation? In what
way did the frameshift mutation change the protein?
11. Which mutation would you predict to be the most harmful to an organism? Explain
your answer.