BLAST

Definition

BLAST, which stands for Basic Local Alignment Search Tool, is a bioinformatics program used to compare a nucleotide or protein sequence against a database of sequences to identify similarities and potential functions. This tool plays a crucial role in genomics and proteomics, enabling researchers to understand evolutionary relationships, predict protein functions, and identify genes associated with specific traits or diseases.

5 Must Know Facts For Your Next Test

1. BLAST can perform various types of searches including nucleotide-to-nucleotide, protein-to-protein, and protein-to-nucleotide alignments.
2. The algorithm behind BLAST identifies high-scoring segment pairs (HSPs) to quickly find local alignments, which makes it faster than traditional alignment methods.
3. BLAST results provide scores and E-values that help determine the significance of the matches found in the database.
4. It has several variations, such as BLASTn for nucleotide sequences and BLASTp for protein sequences, each tailored for specific types of comparisons.
5. BLAST is widely used in research for annotating genes, studying genetic variations, and exploring evolutionary biology.

Review Questions

• How does BLAST facilitate the understanding of evolutionary relationships among species?
  • BLAST helps researchers identify homologous sequences between different organisms by comparing gene or protein sequences. When similar sequences are found across species, it suggests a shared ancestry or evolutionary relationship. This information can be critical in tracing the evolution of specific traits and understanding how different species have adapted over time.
• Evaluate the importance of E-values in interpreting BLAST results and how they impact research conclusions.
  • E-values are vital in assessing the reliability of matches found in BLAST searches. A lower E-value indicates that the match is less likely to have occurred by chance, thus providing more confidence in the biological significance of the alignment. Researchers must carefully consider these values when drawing conclusions about gene functions or evolutionary relationships to ensure that their interpretations are based on statistically significant data.
• Assess the implications of using BLAST for annotating newly sequenced genomes in genomics and proteomics.
  • Using BLAST for annotating newly sequenced genomes has significant implications for understanding gene functions and discovering novel proteins. By comparing newly sequenced genes against established databases like GenBank, researchers can predict the roles of these genes based on known functions from similar sequences. This process not only accelerates genomic research but also aids in identifying potential targets for drug development and understanding genetic diseases at a molecular level.

Related terms

Sequence Alignment: The process of arranging sequences of DNA, RNA, or proteins to identify regions of similarity that may indicate functional, structural, or evolutionary relationships.

GenBank:

A public database of annotated nucleotide sequences and their protein translations, which is often used as a reference in BLAST searches.

E-value: A parameter used in BLAST results that indicates the number of hits one can “expect” to see by chance when searching a database of a particular size; lower E-values indicate more significant matches.