In recent years, biological databases have greatly developed, and became a part of the biologist’s
everyday toolbox (see, e.g., [4]). There are several reasons to search databases, for
instance:
1. When obtaining a new DNA sequence, one needs to know whether it has already been
deposited in the databanks fully or partially, or whether they contain any homologous
sequences(sequences which are descended from a common ancestor).
2. Some of the databases contain annotation which has already been added to a specific
sequence. Finding annotation for the searched sequence or its homologous sequences
can facilitate its research.
3. Find similar non-coding DNA stretches in the database:for instance repeat elements
or regulatory sequences.
4. Other uses for specific purpose, like locating false priming sites for a set of PCR
oligonucleotides.
5. Search for homologous proteins - proteins similar in their sequence and therefore also
in their presumed folding or structure or function.