Computational biology involves the use of. | Agrigyan

• Primary vs. Secondary Biological Databases:
• Primary (Archival) Databases: Store original, experimentally determined, direct sequence and structural submissions submitted directly by researchers.
• Examples: EMBL (European Molecular Biology Laboratory), GenBank (NCBI), DDBJ (DNA Data Bank of Japan), and PDB.
• Secondary (Derived) Databases: Store curated, processed, or value-added information derived from primary records:
• KEGG: Pathway and systems database.
• RefSeq: Curated, non-redundant reference sequence database.
• CATH: Protein domain classification database based on structural coordinates.
• Conclusion: The primary database is EMBL (Option 2).

Correct option: (2) EMBL

• PAM vs. BLOSUM Substitution Matrices:
• Statement (I): The PAM substitution matrices were derived using local multiple alignments. $\implies$ Incorrect.
• PAM (Point Accepted Mutation) matrices (Dayhoff et al., 1978) were derived from global alignments of closely related protein sequences with >85% identity.
• Statement (II): The BLOSUM matrices were derived using substitution frequencies derived from sets of closely related protein sequences. $\implies$ Incorrect.
• BLOSUM (Blocks Substitution Matrix) matrices (Henikoff & Henikoff, 1992) were derived from local multiple alignments of conserved ungapped blocks (BLOCKS database) representing moderately to distantly related proteins (e.g., BLOSUM62 clusters sequences sharing 62% identity or greater).
• Conclusion: Both Statement (I) and Statement (II) are incorrect (Option 2).

Correct option: (2) Both Statement (|) and Statement (II) are incorrect

• Phylogenetic Tree Terminology:
• Branches or Edges: The connecting lines in a phylogenetic tree representing evolutionary lineages over time. (True)
• Internal Branch: A branch connecting two internal nodes (representing an ancestral lineage prior to subsequent divergence events). (True)
• Root: The basal node representing the unique common ancestor of all operational taxonomic units (taxa) present in the tree. (True)
• Conclusion: All (A), (B) and (C) are true (Option 4).

Correct option: (4) All (A), (B) and (C) are true.

• Number of Possible Unrooted Trees:
• For $n$ operational taxonomic units (taxa), the number of distinct unrooted bifurcating phylogenetic trees ($N_u$) is given by the double factorial formula:

$$N_u = (2n - 5)!! = 1 \times 3 \times 5 \times \dots \times (2n - 5)$$

• For $n = 5$ taxa:

$$N_u = (2 \times 5 - 5)!! = 5!! = 1 \times 3 \times 5 = 15$$

• (By comparison, the number of rooted trees for $n = 5$ is $(2n - 3)!! = 7!! = 105$).
• Conclusion: The number of unrooted trees for 5 OTUs is 15 (Option 2).

Correct option: (2) 15