quality:corruption
Virus structure

Each SARS-CoV-2 virion is 60–140 nanometres (2.4 × 10 –5.5 × 10 in) in diameter; its mass within the global human populace has been estimated as being between 0.1 and 10 kilograms. Like other coronaviruses, SARS-CoV-2 has four structural proteins, known as the S (spike), E (envelope), M (membrane), and N (nucleocapsid) proteins; the N protein holds the RNA genome, and the S, E, and M proteins together create the viral envelope. Coronavirus S proteins are glycoproteins and also type I membrane proteins (membranes containing a single transmembrane domain oriented on the extracellular side). They are divided into two functional parts (S1 and S2). In SARS-CoV-2, the spike protein, which has been imaged at the atomic level using cryogenic electron microscopy, is the protein responsible for allowing the virus to attach to and fuse with the membrane of a host cell; specifically, its S1 subunit catalyzes attachment, the S2 subunit fusion.