Practice question

Green fluorescent protein fused to a protein of interest allows non-invasive tracking inside living cells, but requires a system that rejects background and enables time-lapse. Confocal microscopy uses laser excitation with pinhole filtering to capture sharp optical sections through living cytoplasm, minimizing photodamage compared to widefield while providing high signal-to-noise. Time-lapse acquisition of GFP dynamics reveals trafficking between endoplasmic reticulum, Golgi and plasma membrane, cytoskeletal assembly and nuclear import. Alternative modalities like bright field lack molecular specificity, while electron microscopy demands fixation that abolishes movement entirely.