Final answer:
First look at the list of matching hits in a BLASTN report, select a top hit, then click on 'Graphics' to view the sequence's genomic location and explore surrounding sequences. The E-value and alignment score help in determining the best match quality.
Step-by-step explanation:
When analyzing a BLASTN report, which is a part of the Basic Local Sequence Alignment Tool (BLAST), it is advisable to first look at the list of matching hits typically found below the graphic with the horizontal bars. These hits provide a short description for each match found in your query sequence compared to the database. One should select a hit near the top of the list, as they are usually the most relevant, and then view the graphical representation by clicking on “Graphics”. This page reveals where the sequence is located within the entire human genome. The page includes a slider, resembling a green flag, which allows for exploration of surrounding sequences. Moreover, alignments are scored, and the one with the highest score is considered the best alignment; the lower the E-value, the less likely the match is due to random chance and hence the better the alignment is considered.