Abstract: 
Knot theory is the study of how knotted copies of a circle can be embedded in three-dimensional space. In this talk, I will discuss some applications of knot theory to biology. In the past, biologists studied enzymes called topoisomerases, which can cut a DNA strand, allowing another DNA strand to pass through before resealing the break. This action can be modeled as a crossing change on a knot diagram. Therefore, to study topoisomerase action, it is of interest to explore the mathematical question of what types of knots one can obtain by performing crossing changes on a particular knot diagram. After discussing some known results, I will talk about how we can use a different local move similar to the crossing change move to determine which knots are the most biologically possible to occur in proteins.