This animation shows how transcription factors find their binding sites in real time. It is based on data from an imaging method that can track single molecules in a living cell.

Single-molecule imaging is a method that uses super-resolution microscopes to visualize molecules as small as 2–25 nm. The animation was developed using single-molecule data that tracked how two transcription factors, SOX2 and OCT4, find their target binding sites on DNA. As shown, the transcription factors “sample” the DNA sequence (represented in the animation as rapid rotations around the DNA molecule) in a trial-and-error manner, until they finally bind to the right sites.

Note that this animation has no narration. Depending on students’ background, it may be helpful to pause the animation at various points to discuss different structures.