Mathematical Biology Seminar Ethan Levien, Dartmouth College, Tueday, February 11, 2025 2:00pm in LCB 215 Cell Growth, Homeostasis, and Antibiotic Response Abstract: In this talk, I will discuss two problems in single-cell dynamics. The first half will cover cell-size homeostasis and models of single-cell biomass growth. Exponentially proliferating cells must compensate for fluctuations in growth and cell-cycle progression to maintain stable size distributions at the population level. Prior work has examined whether these compensations occur through negative correlations between single-cell growth rates and cell size or through negative correlations between single-cell generation times and cell size. I will introduce novel ways to approach this question and present insights gained from high-resolution mass measurements of lymphocytic leukemia cells. Next, I will discuss new work on gene expression under antibiotic stress. Experiments reveal that abrupt antibiotic exposure leads to divergent cell fates and expression profiles in E. coli, which cannot be explained by conventional models of gene expression noise. Instead, these dynamics require a stochastic framework for resource allocation. In both projects, I will highlight open questions at the interface of biology and mathematics.