Wikipedia:Reference desk/Archives/Science/2020 December 5
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December 5
editDNA polymerase
editI see that all life have DNA polymerase; while also some of the virions do. My question, is whether they have the same enzyme as the life , and do the virions' enzyme have a common descent with those of the living cells. --Exx8 (talk) 00:33, 5 December 2020 (UTC)
- The DNA polymerases are a family of enzymes that varies across species. Enzymes are proteins, and virions do not contain proteins, but they do contain genes, and in some cases these genes contain the code for a DNA polymerase. DNA viruses such as that for hepatitis B may fall in this class; they need DNA polymerase to be replicated, so packing the instructions for infected cells to synthesize it sounds like good policy. The origins of viruses is unclear in general, as is much of the origin of (cellular) life, including which preceded which – or was it co-evolution? But in this specific case it is extremely likely that the viruses that contain code for a DNA polymerase captured the genes from a cell. --Lambiam 08:59, 5 December 2020 (UTC)
- Virions do of course contain proteins, at least the capsid proteins and some proteins needed for the fusion with the cell membrane. I'm not sure whether some virions do contain some ready to use polymerases, but if the first transcription and replication is made by the cell own polymerases, many viruses posses genes for viral polymerases, which are more efficient in processing the viral genome than the native polymerases of the cell. Viral polymerases are often more complex and perform more functions than cell polymerases but there are some low but significant similarities to cell polymerases. Here some generalities about viral polymerases: [[1]].
- Most (if not all) viral proteins must have been originally captured from some living cells and all are subject to mutation and selection, here [[2]] something about the phylogenetic relationships between viral and cell polymerases, here [[3]] some comparisons between DNA-dependent RNA polymerases of the different organisms. 2003:F5:6F09:B100:7185:8061:156A:2E5 (talk) 15:05, 5 December 2020 (UTC) Marco PB
- By "contain" I meant within the protective outer shell. But as it turns out, some viruses express their entire genome as one massive polyprotein, and use a protease to cleave this into functional units. So the assertion in the Virus article that a virion "consists of nucleic acid surrounded by a protective coat of protein called a capsid" is not correct in that unqualified form. --Lambiam 16:11, 6 December 2020 (UTC)
- WP:SOFIXIT.
—107.15.157.44 (talk) 18:10, 6 December 2020 (UTC)
- On further examination, I see that I misunderstood the meaning of "express their entire genome" in the section Protease#Viruses. The viruses that were mentioned as examples there, such as polio, are RNA viruses. The host cell first translates the RNA of the virus into a single protein that is then cut up into functional chunks. I am not sure what is the most appropriate term to use here as the agent of the verb "express", so I have rewritten that sentence to avoid the need for specifying an agent. I have also replaced the viruses mentioned by examples from the cited source. --Lambiam 10:21, 7 December 2020 (UTC)
- Most of the above is not accurate. Many virus particles (virions) contain enzymes. Reoviruses contain an RNA polymerase and retroviruses (HIV for example) contain a DNA polymerase (two in fact). These enzymes are quite distinct from those found in cells and have evolved independently. The Virus article is correct on all counts. 208.127.199.196 (talk) 18:16, 7 December 2020 (UTC)
- The articles states that viruses use enzymes. Where does it say that they contain enzymes? It does state that a virion "consists of nucleic acid surrounded by a protective coat of protein called a capsid". In normal use, that is understood to imply it does not contain other stuff that is essential for replication. --Lambiam 10:55, 8 December 2020 (UTC)
- As I wrote Virus perhaps I should comment. You seem to think that a generalised description of a virus particle should apply to all viruses. It doesn't of course. Not all virus particles contain enzymes, but quite a few do. Some structural proteins are also enzymes. The influenza virus neuraminidase is a good example. HIV contains at least three enzymes, the protease, the integrase and two copies of the reverse transcriptase, (which is A DNA polymerase). Picornaviruses don't contain any enzymes as far as I recall. Measles virus has a an RNA dependant RNA polymerase on board. You said above that virions do not contain proteins. They all do. Nucleoproteins. You were also completely wrong about the origins of viral genes. There is no evidence of their being captured. If you think the Virus article is misleading in this regard, why haven't you mentioned this on the article's Talk Page? This is not the place to be sounding off about an article's perceived deficiencies. Graham Beards (talk) 19:27, 8 December 2020 (UTC)
- I did not mean to sound off, but merely to defend myself. Specifically, I did not claim anywhere the Virus article is wrong, but was nevertheless castigated for (I guess) implying this by not accepting the information imparted by the Virus article that many virus particles contain enzymes. I did indeed not get this from reading the text, but if the information is there, it is so implicit that the suggestion that I (implicitly?) proclaimed it wrong is IMO not justified. --Lambiam 14:25, 9 December 2020 (UTC)
- As I wrote Virus perhaps I should comment. You seem to think that a generalised description of a virus particle should apply to all viruses. It doesn't of course. Not all virus particles contain enzymes, but quite a few do. Some structural proteins are also enzymes. The influenza virus neuraminidase is a good example. HIV contains at least three enzymes, the protease, the integrase and two copies of the reverse transcriptase, (which is A DNA polymerase). Picornaviruses don't contain any enzymes as far as I recall. Measles virus has a an RNA dependant RNA polymerase on board. You said above that virions do not contain proteins. They all do. Nucleoproteins. You were also completely wrong about the origins of viral genes. There is no evidence of their being captured. If you think the Virus article is misleading in this regard, why haven't you mentioned this on the article's Talk Page? This is not the place to be sounding off about an article's perceived deficiencies. Graham Beards (talk) 19:27, 8 December 2020 (UTC)
- The articles states that viruses use enzymes. Where does it say that they contain enzymes? It does state that a virion "consists of nucleic acid surrounded by a protective coat of protein called a capsid". In normal use, that is understood to imply it does not contain other stuff that is essential for replication. --Lambiam 10:55, 8 December 2020 (UTC)
- Most of the above is not accurate. Many virus particles (virions) contain enzymes. Reoviruses contain an RNA polymerase and retroviruses (HIV for example) contain a DNA polymerase (two in fact). These enzymes are quite distinct from those found in cells and have evolved independently. The Virus article is correct on all counts. 208.127.199.196 (talk) 18:16, 7 December 2020 (UTC)
- On further examination, I see that I misunderstood the meaning of "express their entire genome" in the section Protease#Viruses. The viruses that were mentioned as examples there, such as polio, are RNA viruses. The host cell first translates the RNA of the virus into a single protein that is then cut up into functional chunks. I am not sure what is the most appropriate term to use here as the agent of the verb "express", so I have rewritten that sentence to avoid the need for specifying an agent. I have also replaced the viruses mentioned by examples from the cited source. --Lambiam 10:21, 7 December 2020 (UTC)
- WP:SOFIXIT.
- By "contain" I meant within the protective outer shell. But as it turns out, some viruses express their entire genome as one massive polyprotein, and use a protease to cleave this into functional units. So the assertion in the Virus article that a virion "consists of nucleic acid surrounded by a protective coat of protein called a capsid" is not correct in that unqualified form. --Lambiam 16:11, 6 December 2020 (UTC)
Water
editThe general recommendation for staying hydrated drinking water is between one and seven litres https://en.wikipedia.org/wiki/Water#For_drinking — Preceding unsigned comment added by 110.151.43.218 (talk) 14:24, 5 December 2020 (UTC)
- OK? Do you have a question? --OuroborosCobra (talk) 15:11, 5 December 2020 (UTC)
- No, it doesn't say you have to drink this quantity of water, but that the body needs it. Only some part of it you must actually drink as water, the balance comes from food and beverages other than straight water. And of course it makes a difference if you are sitting in your igloo reading a good book or if you are breaking stones at noon in the middle of Sahara. But beside that yes, what is your question? 2003:F5:6F09:B100:7185:8061:156A:2E5 (talk) 15:18, 5 December 2020 (UTC)m Marco PB
- "The U.S. National Academies of Sciences, Engineering, and Medicine determined that an adequate daily fluid intake is: About 15.5 cups (3.7 liters) of fluids a day for men. About 11.5 cups (2.7 liters) of fluids a day for women. These recommendations cover fluids from water, other beverages and food. About 20% of daily fluid intake usually comes from food and the rest from drinks". [4] Alansplodge (talk) 00:46, 6 December 2020 (UTC)
- Please sign your posts. And the OP, what is your question? Do you find 7 litres too much? What about desert operations, 4 gallons per man per day, only drinking water? [[5]]: "Example 2. A 40-man platoon doing a variety of work over an entire day. The platoon requires 4 gallons of water per man per day for drinking" 2003:F5:6F09:B100:7185:8061:156A:2E5 (talk) 20:10, 5 December 2020 (UTC) Marco PB
- "The U.S. National Academies of Sciences, Engineering, and Medicine determined that an adequate daily fluid intake is: About 15.5 cups (3.7 liters) of fluids a day for men. About 11.5 cups (2.7 liters) of fluids a day for women. These recommendations cover fluids from water, other beverages and food. About 20% of daily fluid intake usually comes from food and the rest from drinks". [4] Alansplodge (talk) 00:46, 6 December 2020 (UTC)
- No, it doesn't say you have to drink this quantity of water, but that the body needs it. Only some part of it you must actually drink as water, the balance comes from food and beverages other than straight water. And of course it makes a difference if you are sitting in your igloo reading a good book or if you are breaking stones at noon in the middle of Sahara. But beside that yes, what is your question? 2003:F5:6F09:B100:7185:8061:156A:2E5 (talk) 15:18, 5 December 2020 (UTC)m Marco PB
My question is what does the question mean when it is recommended to drink between one and seven litres. — Preceding unsigned comment added by 110.151.43.218 (talk) 00:27, 6 December 2020 (UTC)
- "The precise amount depends on the level of activity, temperature, humidity, and other factors." ←Baseball Bugs What's up, Doc? carrots→ 00:42, 6 December 2020 (UTC)
- Agree absolutely with Bugs. In terms of quantity there is no 'correct amount', it depends on several other conditions. Richard Avery (talk) 10:05, 6 December 2020 (UTC)
- It means "In one day, don't drink less than one litre; don't drink more than seven." Less than one and you'll become dehydrated under almost all circumstances; drink more than seven and you'll very likely (though not certainly) suffer ill effects. Just how much you need or will want to drink between those two limits depends on many interacting factors including the weather, your solid food intake (which also contains water), how much exercise you're doing, your individual size and metabolism, your state of health, etc., etc.
- As a rough rule of thumb, if your urine is colourless you're drinking enough if not too much; if it's strongly coloured you need to drink more; if its colour is anything other than yellow go see a doctor as soon as possible.
- Drink if you feel thirsty: if your thirst causes you to drink anything approaching the 7-litre upper limit, go see a doctor because this can be a symptom of at least one serious illness. It would be a good idea to see one anyway to ask them what you've been asking here, because they're better qualified to answer than anyone here and they can assess many of the factors personal to you that no-one here can. {The poster formerly known as 87.81.230.195} 2.122.56.237 (talk) 01:34, 6 December 2020 (UTC)
- Are you sure you have interpreted the upper limit correctly? I would parse "To function properly, the body requires between one and seven litres of water per day to avoid dehydration" as meaning that you may need to drink as much as seven litres to prevent dehydration, not that that is the maximum safe limit beyond which you risk water intoxication. The water intoxication article mentions someone who died after drinking 7.6L for a competition, but that is in a short time period, and without urinating (and presumably in addition to whatever they had already drunk that day). Water#For_drinking states that the kidneys can excrete up to 1 litre per hour, which suggests you could drink a lot more than seven litres in one day, as long as you paced yourself, and urinated as needed. Iapetus (talk) 14:17, 7 December 2020 (UTC)
- If there is someone recommending to "drink between one and seven litres", you should ask them what they mean by that. Our article contains no such recommendation. --Lambiam 15:45, 6 December 2020 (UTC)
- It literally states, in a link I won't provide a second time because you can click it above, "To function properly, the body requires between one and seven liters (0.22 and 1.54 imp gal; 0.26 and 1.85 U.S. gal) of water per day to avoid dehydration; the precise amount depends on the level of activity, temperature, humidity, and other factors." Regardless of whether or not that statement is correct, it is written there, so your statement that the text is not in the article is incorrect. --Jayron32 18:36, 7 December 2020 (UTC)
- The amount is written in the statement in the article, but this statement is an observation, not a recommendation, and certainly not a recommendation to drink that amount. --Lambiam 09:01, 8 December 2020 (UTC)
- It is certainly within reason that a person would interpret such a statement as being a recommendation, and without further clarification on how to get the water in your body, drinking is a reasonable expectation for most people. Not everyone is as smart and well read as you. --Jayron32 13:18, 8 December 2020 (UTC)
- It was clear (even to me) that the OP interpreted the statement in the article as a recommendation (making the question, based on a false premise, moot), and continued to do so in spite of the responses given. In view of this apparent continued misunderstanding, however understandable, I thought it would be helpful to state clearly that the article does not contain any such recommendation. --Lambiam 12:42, 9 December 2020 (UTC)
- It is interesting that the OP interpreted the article quoted (Water#For_drinking) as a recommendation. It doesn't read like that to me and of course many experienced editors/readers will be familiar with WP:NOTADVICE which explicitly says the encyclopaedia shouldn't be used as such. Mike Turnbull (talk) 13:32, 8 December 2020 (UTC)
- That's why when interacting with other people, it is important to understand that our own perspective is not the only possible perspective, and to anticipate likely ways in which a person may be understanding the world. While I may not read the statement as such, it doesn't mean it is unreasonable for another person to read it that way. Indeed, it is quite reasonable to interpret a statement, under a header that says "for drinking", that says "the body requires X liters of water" would parse that to read that a person should be drinking X liters of water. That's a possible, and reasonable, understanding of that context. Whether or not the writer of that text intended that meaning, or whether or not you or I read it that way, does not mean a person should be considered unreasonable for reading it different. My perspective is not the only correct perspective. --Jayron32 15:42, 8 December 2020 (UTC)
- Striving for correctness may lead one to an error of false precision in concluding that the body will suffer if it receives (X - 0.1) or (X + 0.1) liters of water. There is no such danger or ambiguity in the case in point where the writer specified the body requires between X and Y liters of water. 84.209.119.241 (talk) 22:11, 9 December 2020 (UTC)
- That's why when interacting with other people, it is important to understand that our own perspective is not the only possible perspective, and to anticipate likely ways in which a person may be understanding the world. While I may not read the statement as such, it doesn't mean it is unreasonable for another person to read it that way. Indeed, it is quite reasonable to interpret a statement, under a header that says "for drinking", that says "the body requires X liters of water" would parse that to read that a person should be drinking X liters of water. That's a possible, and reasonable, understanding of that context. Whether or not the writer of that text intended that meaning, or whether or not you or I read it that way, does not mean a person should be considered unreasonable for reading it different. My perspective is not the only correct perspective. --Jayron32 15:42, 8 December 2020 (UTC)
- It is certainly within reason that a person would interpret such a statement as being a recommendation, and without further clarification on how to get the water in your body, drinking is a reasonable expectation for most people. Not everyone is as smart and well read as you. --Jayron32 13:18, 8 December 2020 (UTC)
- The amount is written in the statement in the article, but this statement is an observation, not a recommendation, and certainly not a recommendation to drink that amount. --Lambiam 09:01, 8 December 2020 (UTC)
- It literally states, in a link I won't provide a second time because you can click it above, "To function properly, the body requires between one and seven liters (0.22 and 1.54 imp gal; 0.26 and 1.85 U.S. gal) of water per day to avoid dehydration; the precise amount depends on the level of activity, temperature, humidity, and other factors." Regardless of whether or not that statement is correct, it is written there, so your statement that the text is not in the article is incorrect. --Jayron32 18:36, 7 December 2020 (UTC)