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Biological Databases – Types of Data and DatabasesNucleotide Sequence Databases (EMBL, GenBank, DDBJ)


Biological Databases – Types of Data and Databases
Nucleotide Sequence Databases (EMBL, GenBank, DDBJ)

1. Introduction

Biological databases are systematic, computerized collections of biological information that allow efficient storage, retrieval, updating, and analysis of large volumes of biological data. With the advent of genome sequencing, molecular biology, and bioinformatics, biological databases have become essential tools in biological research.
These databases support studies in genomics, proteomics, evolutionary biology, taxonomy, medicine, agriculture, and biotechnology.

2. Types of Data Stored in Biological Databases
Biological databases store diverse types of biological information, including:

1. Sequence Data
DNA sequences
RNA sequences
Protein sequences

2. Structural Data

Three-dimensional structures of proteins
Nucleic acid structures

3. Functional Data

Gene functions
Enzyme activity
Regulatory elements

4. Genomic Annotation Data

Gene location
Exons, introns
Promoters and regulatory regions

5. Expression Data

Transcriptome data
Gene expression profiles

3. Classification of Biological Databases
Based on content and level of data processing, biological databases are classified into:

A. Primary Databases

Contain raw experimental data
Direct submissions from researchers
Minimal annotation
Examples:
GenBank, EMBL, DDBJ, Protein Data Bank (PDB)

B. Secondary Databases

Data derived from primary databases
Highly curated and analyzed
Provide functional and structural annotations
Examples:
UniProt, PROSITE, Pfam, SCOP


C. Composite (Integrated) Databases


Combine information from multiple databases
Reduce redundancy
Provide non-overlapping datasets
Examples:
RefSeq, UniGene, Ensembl

4. Nucleotide Sequence Databases

Nucleotide sequence databases store DNA and RNA sequences obtained through sequencing experiments. They are essential for gene discovery, genome analysis, comparative genomics, and evolutionary studies.

The three major global nucleotide sequence databases are:
GenBank (USA)
EMBL-ENA (Europe)
DDBJ (Japan)

These databases function under the International Nucleotide Sequence Database Collaboration (INSDC).


5. International Nucleotide Sequence Database Collaboration (INSDC)


INSDC is a global consortium that ensures:
Free and open access to nucleotide sequence data
Daily exchange of data among databases
Uniform data formats and annotation standards.


Members of INSDC:
GenBank – NCBI (USA)
EMBL-ENA – EMBL-EBI (Europe)
DDBJ – National Institute of Genetics (Japan)

6. GenBank
Overview
GenBank is a comprehensive nucleotide sequence database maintained by the National Center for Biotechnology Information (NCBI), USA. It is one of the largest and most widely used biological databases.
Types of Data Stored

Genomic DNA
cDNA and mRNA sequences
ESTs (Expressed Sequence Tags)
Whole genome sequences
Organelle genomes


7. EMBL (European Molecular Biology Laboratory Database)

Overview
The EMBL nucleotide database is maintained by the European Bioinformatics Institute (EMBL-EBI) and is now part of the European Nucleotide Archive (ENA).



8. DDBJ (DNA Data Bank of Japan)

Overview
DDBJ is maintained by the National Institute of Genetics (NIG), Japan. It mainly accepts sequence submissions from Asian countries but is globally accessible.
Data Stored
DNA and RNA sequences
Whole genome sequences
Environmental and metagenomic data
Special Features
Uses data formats similar to GenBank and EMBL
Exchanges data daily with other INSDC members
Provides online submission tools
9. Comparison of GenBank, EMBL, and DDBJ




➡ All three contain identical data but differ in access portals and management.


10. Importance of Nucleotide Sequence Databases
Preserve genetic information
Support genome sequencing projects
Enable gene identification and annotation
Facilitate evolutionary and phylogenetic studies
Assist in medical, agricultural, and environmental research
11. Applications
Comparative genomics
Molecular taxonomy
Gene cloning and primer design
Mutation analysis
Crop improvement and breeding programmes
12. Conclusion
Biological databases play a central role in modern biological research. Among them, nucleotide sequence databases such as GenBank, EMBL, and DDBJ are primary repositories that store DNA and RNA sequences. Through the INSDC collaboration, these databases ensure global data sharing, accuracy, and accessibility, making them indispensable resources for genomics, bioinformatics, and biotechnology.




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