Nucleosomes form the fundamental repeating units of eukaryotic chromatin. They consist of a segment of DNA wound in sequence around eight histone proteins (blue) and of about 146 base pairs.The paler segment is another nucleosome. Source: PDB entry 3afa.
Ubiquitin protein molecule, 3D rendering. Ubiquitin is a molecular tag that indicates proteins marked for recycling. Cartoon representation combined with semi-transparent surfaces.
Commercial airplane flying above dramatic clouds during sunset.