Official websites use .gov
A
.gov website belongs to an official
government organization in the United States.
Secure .gov websites use HTTPS
A lock (
) or https:// means you've safely
connected to the .gov website. Share sensitive
information only on official, secure websites.
(a) Tubulin proteins (left, scale bar ∼5 nm) polymerize into microtubules (right, scale bar ∼25 nm). (b) Highly ordered arrays of tryptophan amino acids (left, in blue) absorb ultraviolet radiation collectively with strong transition dipole moments (right, in red, scale bar ∼25 nm). Reproduced with permission under a Creative Commons Attribution 3.0 License from ref (406). Copyright 2019 IOP Publishing Ltd.
