Four rotatable bonds, one slider each. Drag any of them and watch that specific segment of the tail swing — everything upstream of it stays put, since a dihedral only rotates the atoms downstream of its axis bond.
g+ (≈60°), t (≈180°), or g- (≈-60°) — and how far off it you are. Defaults start at all-trans, a real, commonly observed extended lysine rotamer. One simplification worth knowing: these four sliders move independently here, but in real proteins the chi angles aren't fully independent of each other — some combinations pack better than others, so rotamer libraries report which combinations are common, not just which single-bond positions are common in isolation.