Which of the following is a literature database? | Agrigyan

• History and Foundations of PAM and BLOSUM Matrices:
• Statement in Option 4: PAM was discovered by S. Henikoff and J. Henikoff in 1992 and BLOSUM by Margaret Dayhoff in 1970s. $\implies$ NOT true (Inverted).
• PAM (Point Accepted Mutation) matrices were developed by Margaret Dayhoff and colleagues in 1978.
• BLOSUM (Blocks Substitution Matrix) matrices were developed by Steven Henikoff and Jorja Henikoff in 1992.
• Statements 1, 2, and 3 are correct:
• BLOSUM is derived from local multiple alignments of ungapped conserved blocks (BLOCKS).
• PAM is derived from global alignments of closely related proteins.
• Low BLOSUM numbers (e.g., BLOSUM45) and high PAM numbers (e.g., PAM250) detect distant homologues.
• Conclusion: Option 4 is not true.

Correct option: (4) PAM was discovered by S. Henikoff and J. Henikoff in 1992 and BLOSUM by Margaret Dayhoff in 1970s.

• Pairwise Sequence Alignment Methods:
• Pairwise sequence alignment algorithms include graphical dot matrix analysis, dynamic programming (Needleman-Wunsch, Smith-Waterman), and word/heuristic methods (FASTA, BLAST). (True)
• A dot matrix plot visualizes repetitions, direct and inverted repeats, and insertions/deletions as parallel or perpendicular diagonals off the main diagonal. (True)
• The Needleman-Wunsch algorithm is designed for global sequence alignments, whereas the Smith-Waterman algorithm is used for local sequence alignments. (False)
• Conclusion: Only (A) and (B) are true (Option 2).

Correct option: (2) Only (A) and (B) are true.

• Accession Number Formats in Biological Databases:
• Statement (I): The accession number of GenBank/EMBL/DDBJ nucleotide sequence records is usually one letter followed by five digits or two letters followed by six digits. $\implies$ True.
• Examples: U12345 (1 letter + 5 digits) or AF123456 (2 letters + 6 digits).
• Statement (II): The accession number of RefSeq nucleotide sequence records is three letters followed by five digits. $\implies$ False.
• NCBI RefSeq accessions consist of a distinct two-letter prefix followed by an underscore and six or more digits (e.g., NM_123456, NP_123456, NC_123456).
• Conclusion: Statement (I) is true but Statement (II) is false (Option 3).

Correct option: (3) Statement (I) is true but Statement (II) is false.