BLAST searches and related applications are essential for analyzing gene and protein sequences. Define BLAST, describe basic features of this bioinformatics tool, and give an example of information provided by a BLAST search.

BLAST, or Basic Local Alignment Search Tool, is a widely used bioinformatics tool that helps in finding similarities between nucleotide or protein sequences in a large database. It is an efficient and rapid method to compare a query sequence with a database of sequences and identify potential homologous sequences.

Some basic features of BLAST include: 1. It is a heuristic algorithm, which means it does not guarantee to find the optimal alignment between the query and database sequences, but it is designed to give accurate results quickly. 2. BLAST can be used to compare nucleotide sequences (DNA or RNA) and protein sequences. 3. BLAST provides various search programs, such as BLASTN for searching nucleotide databases, BLASTP for searching protein databases, and BLASTX for translating a nucleotide query into protein and searching protein databases. 4. It allows users to adjust parameters, like the scoring matrix and gap penalties, allowing for customization according to their research needs. 5. The output of a BLAST search includes a list of alignments ranked by a statistical measure called Expectation value (E-value), which estimates the number of alignments occurring by chance.

Suppose a researcher has identified a novel gene sequence from a plant and wants to know if this gene is conserved in other organisms. The researcher can perform a BLAST search using the newly identified gene sequence as a query against a database of nucleotide sequences. The BLAST results will display a list of similar sequences found in the database ranked by E-value (lower E-values indicate higher similarity). This information will help the researcher determine if the novel gene has homologous sequences in other organisms, and further analyze the function, evolution, and potential applications of the gene.