Greetings! My name is James Pelletier, and I am a 6th year graduate student in the Center for Bits and Atoms and the Department of Physics at MIT. I am interested in how nonliving molecules work together to make living systems capable of metabolism, growth, replication, homeostasis, and adaptation. In particular, we are interested in top-down and bottom-up approaches to synthetic cells. We hope to combine the most complex nonliving molecules, such as cytoplasm and chromosomes, to make the least complex living systems.

From the top-down we are investigating a bacterium with a minimal genome, in collaboration with John Glass of the J. Craig Venter Institute and Elizabeth Strychalski of the National Institute of Standards and Technology. For context, humans contain about 20000 genes, the bacterium Escherichia coli contains about 4000 genes, and the minimal cell contains just 473 genes. To our surprise, 149 of them do not have a known function, even though all are essential and the cell would die without any one of them. Therefore, we now know which genes a minimal cell contains, but we do not understand how the genes work. By imaging the growth and replication of single cells in microfluidic devices, we are now investigating how the minimal cell lives.

From the bottom-up we are reconstituting cellular phenomena in eukaryotic cytoplasmic extract from frog eggs, with Timothy Mitchison and Nikta Fakhri. For example, we are investigating geometrical and mechanical aspects of intracellular scaffolds such as microtubules, actin, and endoplasmic reticulum. I enjoy thinking about these cytoskeletal scaffolds as “LEGO soup,” composed of many different molecules that are constantly using energy to self-organize, assembling and disassembling to make different structures that can do different jobs at different times.