The codons for the various amino acids are given below. Answer the question.
In the given RNA the nitrogenous base at position 2 of the fourth codon is replaced by G. What will be the effect on protein synthesis?
AUG GUU AGU UAA
Answer & explanation
Correct answer: option 3
The correct answer is Option (3) → No effect on protein synthesis
Original RNA sequence: AUG GUU AGU UAA
- AUG: Start codon (methionine)
- GUU: Valine
- AGU: Serine
- UAA: Stop codon
The question mentions that the nitrogenous base at position 2 of the fourth codon (which is UAA) is replaced by G, turning it into UGA.
- UAA is a stop codon, signaling the end of protein synthesis.
- UGA is also a stop codon.
Effect of the Mutation:
Both UAA and UGA are stop codons, so replacing U with G in the second position of the fourth codon does not change the outcome. The stop signal is still present, meaning protein synthesis will terminate at this point as usual.
So, there is no effect on protein synthesis because the mutated codon still functions as a stop codon.