Bio-medical Ontologies Maintenance and Change Management

Substructure Analysis of Metabolic Pathways 239
Fig. 1. TCA cycle biological network of Homo Sapiens [26]
methodologies, integrating heterogeneous data and understanding interactions
with other data and various conditions. A system cannot be comprehended
as a part but as a whole system.
Fundamentally an organism is a system itself as well as a property of
a bio-ecosystem. The organism has a systematically well-organized structure
consisting of multi-level compositions such as tissue, organ and organ system,
all of which are based on a cell as a functional and structural basic unit.
Each constituent is cooperating with others interactively as well as organized
systematically. Even the basic unit, the cell, is also a system itself. A cell
has a variety of biomolecules that are working with interactive relationships
among them.
A huge amount of biological data has been generated by long-term research.
Each result cannot allow us to understand a whole biological system,
because any molecule or constituent in the organism never works alone. They
always interact with others in the system. For this reason an organism should
be explored as a system.
A biological system can be described as a large biological network, which
consists of numerous small networks. Each network has various biomolecules
and their relationships. Generally a cellular system is represented by three
kinds of biological networks: metabolic pathways, protein-protein interactions
and gene regulatory networks [16]. Our research is currently focused on the
metabolic pathways.