The normal sequence of aparticular protein is given here, along with several mut

Question

The normal sequence of aparticular protein is given here, along with several mutantversions of it. For each mutant, explain what mutation occurred inthe coding sequence of the gene. Assume only a single mutationalevent explains each altered amino acid sequence.

(…) = multipleunspecified amino acids

Normal:Met-Gly-Glu-Thr-Lys-Val-Val-(…)-Pro

Mutant1:             Met-Gly

Mutant2:             Met-Gly-Glu-Asp

Mutant 3:            Met-Gly-Arg-Leu-Lys

Mutant4:             Met-Arg-Glu-Thr-Lys-Val-Val-(…)-Pro

Explanation / Answer

In mutant 1, the protein sequence is Met-Gly, and then the proteinstops. This means that the third amino acid must have been changedfrom a Glu codon to a stop codon. You can look at a codon table andsee how this change can occur on a DNA level. In mutant 2, the first 3 amino acids are the same, then the 4th oneis changed, and the proteins stops. Compare the 4th amino acid fromthe mutant, Asp, to the 4th amino acid in the normal protein, Thr.Once again, look at a codon table and see how this change may haveoccurred. For the next two mutants, look to see how the amino acid sequencehas changed compared to the normal protein. You can then look at acodon table to see what nucleotides have to change in order to gofrom one amino acid to another. Note that in mutant 3 the proteinis truncated, meaning that a stop codon has been introduced. Good luck!

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