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How to Use NCBI Blast

The BLAST search tool can be used to identify matches in gene sequences by comparing the sequence you enter with all recorded sequences in relevant databases. Follow these steps to submit a search and receive results quickly and easily.


  • Step 1: Open search page Open the Basic Local Alignment Search Tool page from the National Center for Biotechnology Information website by clicking on BLAST in the Popular Resources menu.
  • Step 2: Choose program Choose a BLAST program to run from the Basic BLAST menu; read the short descriptions of each program to figure out which one you should run.
  • Step 3: Select database On the program page, select the BLAST database you want to use from the Database pull-down menu under Choose Search Set.
  • Step 4: Enter sequence Copy and paste the Accession number, GI number, or FASTA formatted sequence into the large text box under Enter Query Sequence.
  • TIP: Choose search type Many Accession and FASTA sequences can be located using NCBI’s Entrez Gene site at "": GI numbers can be found using the Sequence Revision History tool at "":
  • Step 5: Submit Click on the BLAST button to submit your search; the page will refresh when the results are ready.
  • FACT: The first isolation of DNA was performed by Swiss biologist Friedrich Miescher in 1869.

You Will Need

  • Internet access

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