Having simple methods of illustration is essential to scientific thinking. To complement the abstract sketches regularly used in cell biology, we propose DynBioSketch, an easy-to-use digital modeling and animation tool, enabling biologists to resort to less simplified representations when necessary without having to call professional artists. DynBioSketch is an interactive sketching system dedicated to the design and communication of biological phenomena at the cellular scale that can be illustrated in a few minutes of animation. Our model integrates 3D modeling, pattern-based design of 3D shape distributions, and sketch-based animation. These elements can be combined to create complex scenarios such as the infection phenomenon on which we focus, allowing a narrative design adapted to communication between researchers or educational applications in biology. Our results, along with a user study conducted with biology researchers, highlight the potential of DynBioSketch in enabling the direct design of dynamic visual summaries that convey relevant information, as shown in our infection case study. By bridging the gap between abstract representations used by experts and more illustrative depictions, DynBioSketch opens a new avenue for communicating biological concepts.