Question

During transcription the DNA base sequence is transcribed into a complementary mRNA sequence. A codon table like the one shown below lists the amino acids coded for by particular triads of mRNA bases. A segment of DNA has undergone a mutation in ukieh one nucleotide has been changed. The original sequence was ACG and the new sequence is ACA. Use the codon table whether or not this mutation will cause a change in the phenotype of the organism.
a. It is impossible to determine if a change in phenotype will occur using only the DNA sequence.

b. No, even though the DNA sequence changed, the sequence still codes for the same amino acid, so no change in phenotype will occur.

c. Yes, the phenotype of the organism would change because any change in the DNA sequence will cause a change in phenotype.

d. Yes, the phenotype of the organism would change because a new amino acid will be coded for.

Answer 1

Answer: Option B) No, even though the DNA sequence changed, the sequence still codes for the same amino acid, so no change in phenotype will occur.

Explanation:

Since the triplet codon ACG codes for the amino acid threonine, so also ACA codes for threonine, the single base change of Guanine (in ACG) to Adenine (ACA) is insignificant due to the degeneracy of the genetic code.

Thus, the sequence still codes for the same amino acid, so no change in phenotype will occur