Question

Which one of the following tools is used to compare all the possible six-open reading frames of a given nucleotide query sequence with all the available six-open reading frames of the nucleotide sequence database?

• A. BLASTN
• B. BLASTX
• C. TBLASTN
• D. TBLASTX

Hint:

Use TBLASTX when both the query and the database are nucleotide sequences, but you want protein-level comparison across all six reading frames.

Answer 1

The Correct Option is D

To compare six reading frames of a nucleotide query with six reading frames of a nucleotide database, both sequences must be translated.
BLASTN: Nucleotide vs nucleotide → no translation.
BLASTX: Nucleotide query (translated) vs protein database.
TBLASTN: Protein query vs translated nucleotide database.
TBLASTX: Translates the nucleotide query into 6 frames AND translates the nucleotide database into 6 frames → 36-frame comparison.
Thus, TBLASTX is the only tool performing 6×6 frame comparison.