Final answer:
To identify the DNA segment used as a template during transcription for a given polypeptide chain, the corresponding mRNA codons should be determined and then matched to the complementary DNA template sequence. This process involves referencing the genetic code to find the mRNA codons for each amino acid and then deducing the reverse complement DNA sequence that served as a template.
Step-by-step explanation:
In the context of transcription, RNA polymerase catalyzes the formation of an RNA strand complementary to the template DNA strand. To determine which segment of DNA was used in the synthesis of the given polypeptide chain arg-gly-phe-phe-val-asp-arg, one must identify the codons that correspond to these amino acids and then determine the complementary DNA sequence.
The sequence of RNA formed during transcription is complementary to the template strand, meaning that if a certain amino acid sequence is produced, we would need the corresponding codons for that amino acid sequence to be present in the mRNA. By deducing the mRNA codons, one can then infer the DNA template strand sequence which would be the reverse complement of the RNA sequence.
For example, the codon for arginine (Arg) could be CGU in mRNA which corresponds to a template DNA strand with the base sequence GCA. Following this principle for the entire amino acid sequence, one would be able to determine the respective template DNA strand.