Question

Which of the following mRNA sequences could code for the polypeptide met-arg-ser-leu-glu?

5' ATGGAGGTTCGATGCGTA 3'
5' AUGAGUAGCUUCGAGUGG 3'
5' AUGCGUAGCUUGGAGUGA 3'
5' AUGCUAAAUGUGCGAUGA 3'

Answer 1

5'-AUGCGUAGCUUGGAGUGA-3'

Step-by-step explanation:

(a) Break the string into triplets.

5'-AUG-CGU-AGC-UUG-GAG-UGA-3'

The string contains six codons.

The initiation codon is AUG (Met)

That eliminates Options 1 and 4.

(b) Identify the stop codon

There are six codons, so the sixth is the stop codon, which must be UAA, UGA, or UAG .

That eliminates Option 2, which ends with UGG.

The correct answer must be Option 3.

(c) Check

Translate the codon string.

5'-AUG-CGU-AGC-UUG-GAG-UGA-3

met arg ser leu glu stop

That's the correct sequence.