Question

4. In the following sequence, we see a stop codon (in bold) followed by a start codon (Underlined) Assuming the cell is normal and is capable of carrying out translation, would this particular RNA fragment be translated (explain why or why not) (6 pts)? 5'-AUCGAUAACUAUGCCCG..G ACGGAGCUAGCCCAAAAAAAAAAA-3 Concerning the RNA strand shown above, name three different proteins you might find attached to this RNA fragment and show where each might be attached (4 pts)

Answer 1

The AUG highlighted here will act as a new Start codon. This is because the sequence from 5' end upto the AUG is the 5'- untranslated region ( 5' UTR). This region is not translated but is required for further regulation of the translation process. The AUG highlighted is the start codon here. Secondly we must notice that the stop codon UAA although present is not in frame, meaning not following the triplet codon rule from the 5'end. The highlighted AUG is the first AUG from the 5' end so a probable start site.

3 proteins found attached to this mRNA would be

Ribosome on ribosome binding site ( found prior to the start codon), methionine t-RNA which will bind to codon AUG and start translation and 5' cap binding protein that protect the 5' cap from exonuclease activity in the cell.