The normal (wild-type) version of a particular protein includes a stretch of ami
ID: 93554 • Letter: T
Question
The normal (wild-type) version of a particular protein includes a stretch of amino acids as follows:
MET-TRP-VAL-ASP A mutant arose in this strain as a result of treatment with a mutagen known to change, delete or add single bases.
A new amino acid sequence of the mutant is now: MET-MET-GLY-STOP
Answer the following questions by referring to the attached genetic code.
a) Show the probable sequence(s) for mRNA which codes for this sequence of amino acids in the wild-type.
b) Show the new mRNA sequence in the mutant.
c) State specifically what mutational event the mutagen caused.
Explanation / Answer
Protein is formed from the mRNA through the process of translation.
1. Met - AUG,
Trp - UGG
Val - GUU, GUA, GUC, GUG
Asp - GAU, GAC
So the probable sequence of the mRNA would be
AUGUGGGUU(G,C,A)GAC(U)
B) The new mRNA sequence in the mutant would be
AUGAUGGGU(C,A,G)UAA/UAG/UGA
C) This is a nonsense mutation in which the mutation causes the protein to be shortened by replacing the bases in such manner that it results in shortening of the protein.