7.342  Systems Biology: Stochastic Processes and Biological Robustness (Adv Undergrad Seminar)

Molecular biology has been extremely successful in deciphering the details of specific cellular biochemical interactions, such as those that control inter- and intracellular signaling and gene expression.  However, a full understanding of cellular function will require an understanding of how all of these interactions work together in a network to perform particular tasks. Such an understanding is the goal of the new field of systems biology.  In this seminar, we will discuss some of the main themes that have arisen in this field, including the concepts of robustness, stochastic cell-to-cell variability and the evolution of molecular interactions within complex networks.  Robustness is a property of many natural biological networks whereby the behavior of the network is insensitive to variations in the numbers of inputs and the strengths of interactions.  One classic example is bacterial chemotaxis, in which the bacterial food sensing mechanism is insensitive to perturbations in the levels of key proteins.  This insensitivity to variations is particularly important given recent work demonstrating that gene expression has a strongly random component, leading to large variations from cell to cell even in genetically identical populations.  In certain networks, this "gene expression noise" can lead to intrinsically random divergence in developmental fates.  We will also discuss networks in a more global context, considering the structure and evolutionary dynamics of networks in whole organisms. Finally, we will study how researchers in the field of synthetic biology are using such new knowledge about biological networks to create artificial gene networks capable of performing new functions.  Examples range from simple genetic switches and oscillators to the transplantation of entire networks capable of producing drugs, biofuels, and synthetic materials.