Question

7-68 You have discovered an alien life-form that surprisingly uses DNA as its genetic material, makes RNA from DNA, and reads the information from RNA to make protein using ribosomes and tRNAs, which read triplet codons. Because it is your job to decipher the genetic code for this alien, you synthesize some artificial RNA molecules and examine the protein products produced from these RNA molecules in a cell-free translation system using purified alien tRNAs and ribosomes. You obtain the results shown in Table.

From this information, which of the following peptides can be produced from poly UAUC?
(a) Ile-Phe-Val-Tyr
(b) Tyr-Ser-Phe-Ala
(c) Ile-Lys-His-Tyr
(d) Cys-Pro-Lys-Ala

Answer 1

Without full knowledge of the alien genetic code, we cannot conclusively determine the peptide that could be produced from poly UAUC, but based on universal genetic code assumptions, UAU would code for Tyr and C is incomplete information.

Step-by-step explanation:

To determine which peptide can be produced from the artificial RNA sequence poly UAUC, we must first know the genetic code that the alien life form uses. Based on the available information, we know that UUU codes for phenylalanine, AAA for lysine, and CCC for proline. Since the artificial RNA provided is a repeating unit of UAUC, we can break it into codons UAU and C which would specify particular amino acids if we knew the genetic code for those particular codons.

Without full knowledge of the alien genetic code, we cannot conclusively determine which peptide could be produced from poly UAUC. Ideally, we would need a table or experimental data revealing what amino acid each codon corresponds to in the alien's genetic code. Since the genetic code is almost universal, if we hypothesize that it is the same as on Earth, then UAU would code for tyrosine (Tyr) and C would not form a complete codon on its own, making it impossible to determine without additional context.