Basic Local Alignment Search Tool (BLAST)

Question 1

main NCBI tool for comparing a protein or DNA sequence (query) to other database sequences (target) = reveals related sequences

finds regions of local similarity between sequences having both speed and sensitivity (heuristic local alignment)

Answer 1

Basic Local Alignment Search Tool (BLAST)

Question 2

What program to use to compare a protein query to a database of proteins.

Answer 2

BLASTP

Question 3

What program to use to compare both strands of a DNA query against a DNA database

Answer 3

BLASTN

Question 4

What program to use to translate a DNA sequence into 6 protein sequences using all 6 possible reading frames, and then compare each of these proteins to a protein database

Answer 4

BLASTX

Question 5

What program to use to translate every DNA sequence in a database into 6 potential proteins, and then compare the protein query against each of those translated proteins.

Answer 5

TBLASTN

Question 6

What program is the most computationally intensive BLAST algorithm. It translates DNA from both a query and a database into 6 potential proteins, then performs 36 protein-protein database searches.

Answer 6

TBLASTX

Question 7

BLAST: Search Statistics

the number of different alignments with scores equivalent to or better than S (similarity score) that are expected to occur by chance in a database search; affected by the scoring system, size of the database, and size of the query

Answer 7

E = expect value

Question 8

probability of a chance alignment occurring with the score in question or better; closer to zero the better

Answer 8

p-value