Essentials of Genetics 9th Edition by Michael Palladino William Klug, Michael Cummings, Charlotte Spencer

Exercise 15

Shown here is a theoretical viral mRNA sequence
5?-AUGCAUACCUAUGAGACCCUUGGA-3?
(a) Assuming that it could arise from overlapping genes, how many different polypeptide sequences can be produced? Using the chart in Figure, what are the sequences?
(b) A base substitution mutation that altered the sequence in part (a) eliminated the synthesis of all but one polypeptide. The altered sequence is shown below. Use Figure to determine why it was altered.5?-AUGCAUACCUAUGUGACCCUUGGA-3?
FIGURE The coding dictionary. AUG encodes methionine, which initiates most polypeptide chains. All other amino acids except tryptophan, which is encoded only by UGG, are encoded by two to six triplets. The triplets UAA , UAG, and UGA are termination signals and do not encode any amino acids.