Consider an mRNA strand that has a sequence of base pairs of GUU CUA ACU. Suppose a substitution mutation occurred in the DNA, resulting in the last base in the first codon of the mRNA to be replaced by Cytosine. Using the codon chart below, a) identify which amino acid will now be formed, and b) explain why this mutation would not result in a phenotypic change. Your answer should be in 2-4 sentences.
Grading Considerations:
Your answer must include:
Correct amino acid (abbreviation from chart) formed from new mRNA sequence
Explanation on why this mutation would not have any effect on the phenotype of the organism
Your answer should be 2-4 sentences in length. In an effort to combat plagiarism, answers longer than 5 sentences will not be considered. Answering concisely and to the point is evidence of your understanding of the topic.
(2 points)
a) The new mRNA sequence resulting from the mutation would be GUCUAACU. According to the codon chart, this codon (GUC) codes for the amino acid Valine (Val).
b) This mutation would not result in a phenotypic change because the codon GUC still codes for the same amino acid Valine (Val) as the original codon GUU. A substitution mutation in the third position of a codon often does not lead to a change in the amino acid sequence, as there is redundancy in the genetic code.