BLAST (Basic Local Alignment Search Tool)

INTRODUCTION

     BLAST, Basic Local Alignment Search Tool is an algorithm for comparing primary biological sequence information from, such as the nucleotides of DNA sequences of the same or different organisms. A BLAST search enables user to compare a query sequence with the information that keep in database of sequences. The software will emphasizes regions of local alignment to detect relationships among sequences which share only isolated regions of similarity.

     There are several Blast programs with different functions such as:

blastp - Compare an amino acid query sequence against a protein sequence database.
blastn - Compare a nucleotide query sequence against a protein sequence database.
blastx - Compare an nucleotide query sequence translated in all reading frames against a protein sequence database.
tblastn - Compare a protein query sequence against a nucleotide sequence database dynamically translated in all reading frames.
tblastx - Compares the six-frame translations of a nucleotide query sequence against the six-frame translations of a nucleotide sequence database.



How to perform a search in BLAST?

Here's the guide to perform a BLAST search.

Step 1. Enter the NCBI website.

Step 2. Click into the program need to be perform.

Step 3. Key in the data need to be search.

Step 4. The software will take some time to generate the resuts.

Step 5. The results is shown as above.

     Conclusion, the BLAST programs improved the overall speed of searches while retaining good sensitivity (important as databases continue to grow) by breaking the query and database sequences into fragments ("words"), and initially seeking matches between fragments. As result, it can identified a unknown species sample or find homologous species within a shorten time which is beneficial to all researchers.