Cells have been described as networks of interacting proteins (see e.g. Vogelstein, Bert, David Lane and Arnold J. Levine. 2000. "Surfing the p53 network". Nature 408, 307 - 310 (November 16, 2000)). But the cell as a living thing -- that metabolizes, reproduces, reacts and evolves is more than the sum of its molecular parts. The network in this case is much more that its parts.

Sharon Begley's Science Journal column on April 2, 2004, Researchers Exploring 'What Is Life?' Seek To Create a Living Cell (may need a subscription or to register) describes various efforts by scientists to construct a cell that reflects the qualities of "life".

"One of the deepest mysteries in biology is how molecules that are no more alive than the tip of a pencil can form a reproducing, metabolizing, evolving organism. If you plop a droplet of any of the molecules that make up living cells (fats, amino acids, water, DNA, other organic molecules) onto a glass slide, it just sits there. No one would mistake it for a living thing. Yet when the right ingredients assemble in the right proportions, the result comes alive, as it did on Earth some 3.8 billion years ago.

"The transformation is so profound that most scientists until the 19th century believed in the theory called vitalism. This holds that living things possess a mysterious "vital spark" that endows them with life, and that life cannot be explained by mere chemistry and physics. But today, harnessing no more than thermodynamics, electromagnetism and chemistry, scientists are taking steps toward creating a living cell."

Researchers have constructed self-replicating vesicles that function like the cell membrane, others have gotten amino acid molecules to chain together into synthetic RNA molecules. Others have discovered that clay, of all things, "can speed up the conversion of little clusters of molecules into vesicles, making the formation of a cell membrane even easier. Inside the vesicle, the clay particles grab hold of short bits of RNA and assemble them into a long strand. Voila: a little sphere containing genetic material able to grow and copy itself." ("But now, O Lord, thou art our father; we are the clay, and thou our potter; and we all are the work of thy hand.", Isaiah 64:8)

"The missing ingredient in this cell wannabe is metabolism, but Steen Rasmussen of Los Alamos National Lab thinks he can provide it. He and Liaohai Chen of Argonne National Lab have designed a microscopic container with metabolic molecules and genes whose electrical properties drive metabolic reactions. The scientists have demonstrated experimentally that this micrometabolism can produce exactly the molecules the container is made of (so the system would be able to grow)."

Begley concludes: "If researchers manage to create living cells from scratch, their mastery of the machinery of life could blur the line between alive and not-alive. Combining the traits of artificial cells with nanotechnology, Dr. Rasmussen and colleagues wrote in a recent issue of Science [Transitions from Nonliving to Living Matter, Science 2004 303: 963-965], could produce machines that 'would literally form the basis of a living technology possessing powerful capabilities and raising important social and ethical' questions."

The network transcends even the interactions of its parts to exhibit amazing new qualities.