Question

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If an error in transcription causes the last cytosine in an mRNA sequence that was supposed to read UUG AUC CAA UGC to be replaced with a guanine, which of the following do you predict would happen?

A. Nothing will happen since the last codon will still correspond to threonine.
B. Only three amino acids will be produced instead of four.
C. The last amino acid in the chain will be tryptophan instead of cysteine.
D. The first amino acid in the chain will be glycine instead of arginine.

Answer 1

The correct answer is C. The last amino acid in the chain will be tryptophan instead of cysteine.

During protein synthesis, the genetic information from DNA is transcribed in mRNA. Codons in an mRNA are encoded during translation to form polypeptide chain. During transcription, codons on mRNA sequence was supposed to read as UUG AUC CAA UGC, but an error has occurred in reading of last codon which is UGC on mRNA. Error is that in UGC, the last nitrogenous base C (cytosine is replaced by G (guanine). As a result of this error the codon UGC will become UGG on mRNA. Thus, UGG will translates into an amino acid tryptophan instead cysteine (UGC).

Answer 2

Answer by YourHope:

If an error in transcription causes the last cytosine in an mRNA sequence that was supposed to read UUG AUC CAA UGC to be replaced with a guanine, which of the following do you predict would happen?

C. The last amino acid in the chain will be tryptophan instead of cysteine!

:)