Possible Explanation

Integrated Cellular Organization

Molecular Machines and Integrated Biological Systems • System Integration

Molecular machines operate as parts of larger cellular systems in which energy, information, transport, quality control, regulation, and repair depend upon one another.

The Explanation

A molecular machine rarely functions in isolation. ATP must be produced and supplied. Proteins must be encoded, translated, folded, transported, regulated, repaired, and eventually degraded. Cellular components communicate through networks of signals and interactions.

The result is organization at several levels. Individual proteins form complexes. Complexes participate in pathways. Pathways interact with other pathways. The cell must coordinate these activities while maintaining conditions compatible with life.

Supporting Evidence

Research on protein machines, molecular chaperones, proteasomes, transport motors, and network biology shows extensive functional integration. The ribosome depends upon genetic information and energy. Protein-folding systems act on products of translation. Degradation machinery removes damaged or unneeded proteins. Transport systems move components to locations where they are required.

Limitations

Integration does not automatically imply design. Natural selection can preserve interacting features when those interactions contribute to survival and reproduction. Existing systems can also be modified and incorporated into new relationships over time.

Questions That Remain

How did the dependencies among cellular subsystems arise, and how much of their historical development can be reconstructed from comparative and experimental evidence?

Intelligent Design Response

The design question becomes more significant when systems are considered together. Intelligent Design asks not merely where an individual component came from, but how information, machinery, energy, regulation, and quality control came to function as an integrated whole.

Research Sources

Alberts — The Cell as a Collection of Protein Machines

Bruce Alberts • Cell • 1998

Describes cellular machinery as an interconnected network rather than a collection of isolated molecular devices.

Alberts emphasizes interactions among large protein complexes, supporting the investigation of molecular machines within the larger organization of the cell.

System Integration

Hartwell et al. — From Molecular to Modular Cell Biology

Leland H. Hartwell; John J. Hopfield; Stanislas Leibler; Andrew W. Murray • Nature • 1999

Provides a framework for understanding cellular organization in terms of interacting functional modules.

Hartwell and colleagues move beyond individual molecules toward the organization of biological function into modules and interacting systems.

Functional Modules

Barabási and Oltvai — Network Biology and Cellular Organization

Albert-László Barabási; Zoltán N. Oltvai • Nature Reviews Genetics • 2004

Examines cellular organization through biological networks and interactions among cellular components.

Network biology provides an additional level of organization beyond individual molecular machines and helps explain how cellular functions are coordinated.

Network Organization