Topics to be covered will include: Building blocks of the living cell; thermodynamics of living systems: interactions and kinetic energy, equilibrium and non-equilibrium processes, entropy, temperature, free energy and chemical potential ; diffusion and friction in liquids, Brownian motion; membrane potential, ion pumps and nerve cells; light and molecules: photon absorption and fluorescence; light microscope, fluorescence as a window into cells, optogenetics and fluorescent reporters; two-photon excitation and fluorescence resonance energy transfer; the eye, image formation, and color vision; structural color in animals.