Question

You decide you are going to decipher codons of an unknown mRNA transcript. In a test tube you mix the unknown mRNA template, tRNA with all 20 amino acids, and a large concentration of ribosomal subunits. You end up producing 3 distinct polypeptides of poly- asp, poly-thr and poly-arg. What is the sequence of the unknown mRNA? Write the first 6 letters of the sequence, starting by the 5' end. DO NOT write the numbers, just the nucleotide letters. 

Answer:

Answer 1

Asp: GAU and GAC
Thr: ACU, ACG, ACC, and ACA
Arg: CGU, CGG, CGC, CGA, AGA, and AGG

The mRNA sequence = 5'-GACGAC----3'

Reading frame 1 = 5'-GAC-GAC----3' = Poly-Asp
Reading frame 2 = 5'-G-ACG-ACG----3' = Poly-Thr
Reading frame 1 = 5'-GA-CGA-CGA----3' = Poly-Arg