Biomedical Engineering Reference
In-Depth Information
4
THE ARCHITECTURE OF BIOLOGICAL
NETWORKS
Stefan Wuchty, Erszébet Ravasz, and Albert-László Barabási
Department of Physics, University of Notre Dame, Notre Dame, Indiana
An ambitious goal of contemporary biological research is the elucidation of the structure
and functions of networks that constitute cells and organisms. In biological systems, net-
works appear in many different disguises, ranging from protein interactions to metabolic
networks. The emergence of these networks is driven by self-organizing processes that
are governed by simple but generic laws. While unraveling the complex and interwoven
systems of different interacting units, it has become clear that the topology of networks of
different biological origin share the same characteristics on the large scale. In this chap-
ter, we survey the most prominent characteristics of biological networks, focusing on the
emergence of the scale-free architecture and the hierarchical arrangement of modules.
1.
INTRODUCTION
Understanding complex systems often requires a bottom-up approach,
breaking the system into small and elementary constituents and mapping out the
interactions between these components. In many cases, the myriad components
and interactions are best characterized as networks. For example, the society is a
network of people connected by various links, including friendships (36), col-
laborationships (29,59), sexual contacts (33), or scientific coauthorships (437,8).
Electronic communication relies on two very different networks: the physical
network wiring the routers together (Internet) (1,14) and the web of homepages
linked by URLs (World Wide Web) (2,9,32). Airline, cell-phone, power-grid, or
Address correspondence to: Albert-László Barabási, Department of Physics, 225 Nieuwland Science
Hall, University of Notre Dame, Notre Dame, IN 46556 USA; tel 574-631-5767, fax 574-631-5259
(alb@nd.edu).
165
