Mariel Vazquez University of California, Davis (UC Davis) Mathematics Cellular processes such as replication, recombination, and packing change the topology of DNA. Controlling these changes is key to ensuring stability inside the cell. The cell uses enzymes to simplify DNA topology. Techniques from knot theory and low-dimensional topology, aided by computational tools, now make it possible for us to study the specific action of such enzymes in these processes. I will illustrate the use of these methods with examples drawn from my ongoing study of unlinking of newly replicated bacterial chromosomes.