Science desk
< September 16	<< Aug \| September \| Oct >>	September 18 >

Welcome to the Wikipedia Science Reference Desk Archives
The page you are currently viewing is an archive page. While you can leave answers for any questions shown below, please ask new questions on one of the current reference desk pages.

September 17

Oil and fat yields

Out of avocado oil, beeffat, butter, canola/rapeseed oil, castor oil, chickenfat, cocoa butter, coconut oil, corn oil, cottonseed oil, flaxseed oil, grapeseed oil, lard, olive oil, oliveseed oil, palm oil, palm kernal oil, peanut oil, pumpkin seed oil, rice bran oil, safflower oil, sesame oil, soybean oil, sunflower oil and tallow which need the most and least grams of source organism per gram? (mass right before harvest or slaughter) If you consider the livestock ate like 10 times it's weight in it's life and milk is only ~3% butter is the lowest yielding one an animal fat? (of course a low yielding plant is probably not "economically inefficient", just able to make oil and other valuable products at the same time (i.e. wine and cotton cloth)) Sagittarian Milky Way (talk) 15:18, 17 September 2018 (UTC)[reply]

Does it make sense to measure yield of products with greatly differing molecular weights in terms of grams of source material and grams of product? I'd think moles might be a better measure for the yield efficiency. See atom economy. --OuroborosCobra (talk) 21:42, 17 September 2018 (UTC)[reply]

Flu infection

I was reading our article on the flu and there's a passage that I'm having trouble understanding. It's the second paragraph from here, which says: "Influenza viruses bind through hemagglutinin onto sialic acid sugars on the surfaces of epithelial cells, typically in the nose, throat, and lungs of mammals, and intestines of birds (Stage 1 in infection figure). After the hemagglutinin is cleaved by a protease, the cell imports the virus by endocytosis." (there's are references, but it's offline - and likely beyond my understanding anyway!).

It's the last sentence. Okay, so hemagglutinin exists on the outer shell of the virus particle. This attaches to the sialic acid sugars on the surface of some cells. So far, so good. But where I'm stuck is how the cleaving of the hemagglutinin helps the virus gain entry. Does it act kind of like a key, "unlocking" sialic acid sugars (and therefore the surface of the cell)? If so, how does cleaving (i.e. breaking) the key help the virus? Proteolysis was linked in there, but it's not helping me picture the activity going on. Matt Deres (talk) 16:32, 17 September 2018 (UTC)[reply]

The source cited doesn't say that cleavage is necessary for endocytosis, it's just that the cleavage itself can only be carried out by specific extracellular proteins in mammalian flus and non-pathogenic avian flus. (In highly pathogenic avian flus, it happens inside the cell, and the enzymes involved are ubiquitous.) The actual deal with the cleavage, though, is that the HA protein has a short little loop on its side connecting the HA1 and HA2 subunits. When the loop is snipped, one of the loose ends becomes the fusion peptide described at Hemagglutinin (influenza)#Function of HA in Viral Entry, and the protein's structure also becomes capable of the pH-driven rearrangements necessary for membrane fusion (described at the same link). -165.234.252.11 (talk) 20:38, 17 September 2018 (UTC)[reply]

Ah! Thank you - excellent explanation! Matt Deres (talk) 01:52, 19 September 2018 (UTC)[reply]

Dog flappy leggy bit

Hey guys, I tried Googling to little avail, but I was wondering what that flappy bit connecting a dog's back leg to his body is called. Thanks in advance! Drewmutt (^ᴥ^) talk 18:06, 17 September 2018 (UTC)[reply]