Nucleic Acids and the Genetic Material Problem Set 1

Problem 11: Products after protein synthesis



A synthetic mRNA of repeating sequence 5'-CACACACACACACACAC... is used for a cell-free protein synthesizing system like the one used by Nirenberg. If we assume that protein synthesis can begin without the need for an initiator codon, what product or products would you expect to occur after protein synthesis?

A. one protein, consisting of a single amino acid
B. three proteins, each consisting of a different, single amino acid
C. two proteins, each with an alternating sequence of two different amino acids
D. one protein, with an alternating sequence of three different amino acids
E. one protein, with an alternating sequence of two different amino acids
Given that initiation can proceed with out the AUG methionine codon, translation can start anywhere but must proceed in units of three from the starting point. Thus, possible codons are: CAC,ACA,CAC,ACA, regardless of the starting point. Two codons would give a protein composed of two alternating amino acids.


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Sunday, September 29, 1996
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