What is the BLAST family of search tools?
The “BLAST” acronym stands for Basic Local Alignment Search Tool. A given sequence in the database using matrices that specify scores to either “reward” a match or “penalize” a mismatch. Top scoring matches are ranked to distinguish between a similarity due to ancestral relationship or due to random chance. True matches are further examined thoroughly with other details accessible through Entrez and other tools available at NCBI. What are the differences between directed and random sequencing? Directed Sequencing of BAC Contigs- BAC vectors are capable of carrying inserts as large as 80-100 Kb. The vectors are used to make Genomic Libraries. The overlapping regions are used to assemble the various insets into continuous contigs. The individual contigs are then sequenced by breaking the DNA and cloning into smaller vectors. Since this is a stepwise directed method it is also called as Directed sequencing. Random Shotgun Sequencing- In this method the genome is randomly broken up into si
