Entry #11 - Systems Biology
Monday, November 20th, 2006Seeing the forest for the trees…
The past 120 years of cell and molecular biology has been spent describing and functionally categorizing the trees in the forest. Thanks to the genome projects we may be close to completing the taxonomy of the “trees” in a given “forest.” Now researchers are starting to think about how to see the forest as a whole over time. This attempt has been termed “systems biology.”
For example, we now know quite a bit about the cell cycle and all the elements that make up mitosis, cytokinesis, G1, S, and G2. But why does the first cell division after fertilization in the Purple Sea Urchin (Stronglyocentrotus purpuratus) take two hours when all the subsequent divisions take about an hour? Why do the divisions take one hour and not four hours or thirty minutes? When it happens turns out to be just as important as what happens in developmental biology! It is fine to study the rate of a biochemical reaction, but what are the rate-limiting steps in the overall metabolic network? How do they act in concert to optimally supply cell activities? Do they even optimally support cell activities? Systems analysis is an approach to answering these types of questions.
Nature Reviews has put together a “user guide” to systems biology and a podcast that gives a good feel (and perspective) for the topic. I especially like the essay by Wingreen and Botstein that outlines a graduate course they teach.