You are studying a bacterial gene that produces an octapepti

You are studying a bacterial gene that produces an octapeptide. The sequence of the protein coding part of the RNA is:
5’-AUGUUUGGGCAGGGUAUAACCCGAUGA-3’
(a) Using the genetic code table, write down the amino acid sequence of the protein encoded by this RNA (2 marks):

(b) You isolate a mutant version of this gene and discover that it encodes a protein with the following sequence: Met-phe-gly-gln-val
What type of mutation has occurred in the gene: a single base insertion, single base deletion or single base substitution? Explain how you arrived at this conclusion. (2 marks)

(c) Write out the mutant RNA sequence and indicate the site of the mutation (2 marks)

Solution

RNA 5\'-AUGUUUGGGCAGGGUAUAACCCGAUGA-3’

Protein M F G Q G I T R stop codon

Mutant protein-

The converstion is Glycine to Valine change, which is a misscene mutation GGU to GUU change . The Guanine is converted to urasil which is a purine to pyramide change and called transversion mutation. It is single base substitution.

The mutant RNA is

5\'-AUGUUUGGGCAGGUUAUAACCCGAUGA-3’

The mutation site is underlined