Wikipedia:Reference desk/Archives/Science/2023 July 5

= July 5 =

COVID
What would the physical properties be of a macroscopic quantity of COVID? I know some viruses can crystallize, but what is it like if they weren't? Thornfield Hall (talk) 00:50, 5 July 2023 (UTC)


 * Coronavirus. SARS-CoV-2.png virus causing COVID is SARS-CoV-2. Its virions, like those of all coronaviruses, are globular but have a large number of protrusions, called "spikes" (although these are not pointy like the spikes of a hedgehog). As far as I know, the virions of viruses that crystallize have more tidy shapes with no unruly protrusions, like the neat rods of the tobacco mosaic virus and the almost-spheres of the poliovirus and tomato bushy stunt virus. I expect that in a highly concentrated suspension of coronavirions their spikes would tend to get entangled and keep them from forming any regular arrangement. A mild application of force might locally shear the spikes off. So, if I'm allowed to speculate, I guess it would be a squishy but not fluid substance. --Lambiam 08:52, 5 July 2023 (UTC)
 * Do you think it would have a certain smell or taste? Or what color? Thornfield Hall (talk) 09:30, 5 July 2023 (UTC)
 * A substantial part of the mass is formed by RNA, which is an acid, so one might guess a somewhat tart sensation. However, the RNA is neatly contained in a lipid envelope, so it won't titillate your taste buds. Only the spike proteins are in a position to bind to taste receptors. I doubt that the taste can be predicted theoretically, given our current knowledge; the only way to find out may be experimentally. I can't think of a reason to expect any identifiable taste; most likely the spike proteins will in fact not bind to any receptor. So my best guess is that it would be bland. Our understanding of the sense of smell is even less. Until the proteins start to decompose (rot), I do not expect a smell. Our knowledge of colours is much more advanced, and a simulation using a supercomputer of light waves bouncing off virions might predict some outcome, but this is beyond my ken. --Lambiam 20:13, 5 July 2023 (UTC)
 * Proteins are often beige, so that would be a good first guess. Abductive  (reasoning) 06:51, 6 July 2023 (UTC)
 * Thanks! Thornfield Hall (talk) 06:58, 6 July 2023 (UTC)
 * https://what-if.xkcd.com/80/ --79.22.6.128 (talk) 09:09, 6 July 2023 (UTC)
 * Ah, pus colored. Abductive  (reasoning) 09:32, 6 July 2023 (UTC)
 * Whey cheeses like ricotta are a more appetizing model, although the protein contribution to its solid mass (about 30%) is less than that of fat (more like 40%). Oxidation will turn the proteins more yellow. --Lambiam 10:46, 6 July 2023 (UTC)