The codon chart relates amino acids to the mRNA codons that specify them.
mRNA Codon Chart
Image courtesy of NIH
A DNA triplet has the sequence 3′-ATC-5′. After a single base mutation, the DNA triplet produces an mRNA codon that specifies the amino acid tryptophan (Trp).
What mutation did the DNA triplet undergo?
A.
The nucleotide C was replaced with G.
B.
The nucleotide T was replaced with C.
C.
The nucleotide A was replaced with T.
D.
The nucleotide A was replaced with C.
D. The nucleotide A was replaced with C.
In the original DNA triplet 3′-ATC-5′, the mRNA codon would be 5′-UAG-3′ which does not code for tryptophan. However, if the DNA triplet undergoes a mutation where the nucleotide A is replaced with C, the mRNA codon would become 5′-UCG-3′ which does code for tryptophan.