In the mRNA sequence ACUAGaugCAGCUAUCAUGCACCACCAGAGA where t

In the mRNA sequence ACUAGaugCAGCUAUCAUGCACCACCAGAGA, where the lowercase aug is the translation start site, what is the resulting sequence of amino acids if it were translated? If the underlined A is changed to a U, will it change the encoded protein sequence? Explain your answer. What if the underlined C is changed to a U? Explain your answer. What if both changes are made? Explain your answer.

Solution

Answer:

12A). mRNA: aug-CAG-CUA-UCA-UGC-ACC-ACC-AGA-GA

AA: Met-Gln-Leu-Ser-Cys-Thr-Thr-Org

12B).

mRNA: aug-CAG-CUU-UCA-UGC-ACC-ACC-AGA-GA

AA: Met-Gln-Leu-Ser-Cys-Thr-Thr-Org

The change of A(purine) by U (pyrimidine) is called transversion. This mutation resulted the same amino acid, so the mutation is called silent mutation.

12B).

mRNA: aug-CAG-UUA-UCA-UGC-ACC-ACC-AGA-GA

AA: Met-Gln-Leu-Ser-Cys-Thr-Thr-Org

The change of C(pyrimidine) by U (pyrimidine) is called transition. This mutation resulted the same amino acid, so the mutation is called silent mutation.

12C).

mRNA: aug-CAG-UUU-UCA-UGC-ACC-ACC-AGA-GA

AA: Met-Gln-Leu-Ser-Cys-Thr-Thr-Org

By the mutations, transition & transversion, one amino acid is changed in the peptide sequence, hence the mutation is called missense mutation.