This course connects physics and cell biology to expose how nature utilizes nanoscale machinery and physical processes at the single-molecule level to carry out essential functions in each of our cells. We will: analyze molecular measurements; investigate diffusive and active mechanisms; and apply these concepts to nanoscale processes that move material across membranes, control cell signaling, and regulate DNA. Lastly, we will use the design principles learned in this course to engineer new types of ultrasensitive diagnostic tools. This course does not require a broad knowledge of biology. Instead, we will build this knowledge as the course progresses.