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Alle Dinge sind Gift, und nichts ist ohne Gift, allein die Dosis macht dass ein Ding kein Gift ist (The dose makes the poison) - Paracelsus Poisons (I'm going to use this as an umbrella term for "toxins" and "venom" as well. Bear in mind though, they are not the same thing) have been known since antiquity. Back in the good old days, you figured out if ...


30

Methanol isn't particularly toxic in and of itself, although it's no walk in the park. If methanol flowed through the body without being broken down, it would cause roughly the same kind of harm as ethanol, i.e. intoxication. The real culprit is one of its metabolic products, methanoic acid, also known as formic acid. To understand how formic acid, ...


22

Excursion into simple coordination chemistry: Bonding, backbonding and simple orbital schemes Please refer to Breaking Bioinformatic’s answer for the MO scheme of carbon monoxide, it is very helpful. You might also look at the orbital pictures in this answer by Martin. Carbon monoxide can bind to metal centres via a σ coordinative bond where the HOMO ...


18

Chemist Neil Bartlett in 1962 discovered that Xenon although a noble gas, is able to form compounds with other substances even though it is chemically "inert". Neil Bartlett at the time in 1961, produced an unidentified red solid and discovered that the red solid was a reaction between, gaseous flouride, platinum hexafluoride (PtF6) and oxygen that was ...


18

The enzyme alcohol dehydroganase converts the methanol to formaldehyde in the body. Formaldehyde is then converted to formic acid. Formaldehyde can cause blindness before being converted to formic acid, while formic acid causes acidosis as Williham Totland points out. See Biochemical Aspects of Methanol Poisoning for more information.


16

The answer has to do with pi-backbonding. In essence, the CO molecule has a negative formal charge on the carbon (it's neutral because of the oxygen having a positive formal charge). However, C is quite electropositive, and would like to relieve the stress caused by the negative formal charge. To relieve the stress caused by the negative charge, the CO ...


16

As you already correctly deduced, the discovery of poisons was in former times quite accidental, but once its potency was discovered, the (mis)use of it was predictable. It must also be said that our ancestors were very careless with poisonous substances. The old houses used wallpapers and paint which were spiked with arsenic, lead and antimony. Copper ...


14

If Xeon does not react with any other chemical, how does this happen, from a chemical point of view? If molecules of phospholipids do not react with each other, how do they form biomembranes? If Xenon doesn't react, how can it form host-guest complexes with cryptophanes? It's not necessary to form covalent or ionic bonds to hold the pieces together. Weak ...


13

Carbon dioxide from the atmosphere (or from decaying matter in the ocean) reacts with water to form carbonic acid: $$ \ce{ CO2 + H2O -> H_2CO_3 }$$ and this reacts with calcium ions to form calcium carbonate: $$ \ce{H2CO3 + Ca^{2+} -> CaCO3 + 2H+ }$$ The solubility of calcium carbonate is about $13~\mathrm{mg \over L}$, so if the concentration of ...


13

There are plenty of good sources online explaining the principle behind radiocarbon dating. For instance, the wikipedia explains: During its life, a plant or animal is in equilibrium with its surroundings by exchanging carbon either with the atmosphere, or through its diet. It will therefore have the same proportion of $\ce{^14C}$ as the atmosphere, or in ...


12

Each hemoglobin molecule has 4 subunits (4 hemes each having one iron atom). Each time a molecule (such as oxygen or CO) binds to one subunit, it changes the binding properties of the other subunits. This is referred to as positive "cooperative binding" in the case of hemoglobin, because binding one molecule makes the other sites bind more easily. ...


12

Just because an organism might need a nutrient, whether arsenic or cobalt (which homo sapiens needs for making RBC's) does not mean that the organism is not carbon-based. What had been announced was that an organism used arsenic to replace phosphorus, not carbon, which has since been amended. There is also the question whether the GFAJ-1 microbe is a ...


12

Technically, there is no difference between naturally ripened fruit and artificially ripened fruit... they're both ripened fruit. I suppose you were looking for some sort of simple chemical test to distinguish between them; but like I said, there's no point in it since in both cases you end up with ripe fruit. Fruits normally emit ethene (ethylene) which is ...


12

Yes, it is detailed here and in numerous other places. It refers to a class of reactions, and does not mean "join." From the above-cited page on named reactions: "Click Chemistry" is a term that was introduced by K. B. Sharpless in 2001 to describe reactions that are high yielding, wide in scope, create only byproducts that can be removed without ...


11

I would say that acids are better. Why? Bases and acids dissolve flesh pretty easily (I'm thinking of $\ce{NaOH}$ and $\ce{HCl}$ here, weaker acids/bases -- not so much). Most of our body is made up of proteins, which are overall pretty much neutral (generally). Both acids and bases can dissolve protein. On the other hand, there is one major component of ...


10

I just wanted to point out that everything is toxic in the right proportion. THe problem is with the dose. I think you could drink a bit of methanol without getting particulary harmed. Do not do it, obviously. The LD50 is very low at 5g/kg. Edit: Nothing to do with methanol, but it is a good infographic Source: http://www.compoundchem.com/2014/07/27/...


10

I appreciate above answer by BreakingBioinformatics. However I have been looking for the oxidation reactions involving Fe in this case. Found some useful material here. It is based on the textbook, Chemistry: Principles, Patterns, and Applications, 2007, Bruce Averill, Patricia Eldredge. Note : Following picture only shows the binding of Myoglobin. Here'...


10

Sometimes poisons are discovered by chance. At least that is what happened to me. We were researching on products made with malonodinitrile and enones. Since I was interested in the mechanism, I used milder conditions in the reaction so I could isolate the Michael and Knoevenagel intermediates and in one case a much more complicated product (see here). The ...


9

The reactivity of NHS activated esters has mostly been desribed quite anecdotically. They are susceptible to hydrolysis in water, the kinetics of which is dependent on the nature of the NHS activated group (ester vs carnonate vs carbamate) as well as on the pH of the reaction buffer1, which is one way to show that primary amines are not the only nucleophile ...


9

The reason behind the bitterness of most fruits is due to presence of Tannin in them. Tannin is a naturally occurring polyphenol found in plants, seeds, bark, wood, leaves and fruit skins. Tannin tastes bitter,dry and astringent and you can feel it specifically on the middle of your tongue and the front part of your mouth. Besides the peels of fruit, we ...


9

Acrylamide is a Michael acceptor. All Michael acceptors are potentially carcinogenic because DNA can act as a Michael donor. This Michael reaction can damage the DNA, which can ultimately develop into cancer. Of course how well a certain Michael acceptor reacts with DNA depends on its chemical structure (i.e. the carbon chain and other function groups as ...


9

Plaques are continually being removed from arteries by natural mechanisms within the body. Statin use, when combined with aggressive dietary changes, can slow down the rate of plaque deposition to the point that the rate of plaque removal is actually higher than the rate of plaque deposition, and, as a consequence, plaque thinning can be observed. Reducing ...


9

It stands for inorganic phosphate (Pi). When ATP is broken down into ADP, energy is released along with a phosphate. You can visualise this if you look at the structure of ATP. ADP is then also able to be broken down into AMP and more Pi


9

In Principles of Nucleic Acid Structure, W. Saenger argues that hydrogen-bonded bases contain at least two hydrogen bonds (forming a "cyclic" pattern). Often, there is a tautomeric form possible that also makes two hydrogen bonds, with two covalent bonds turning into hydrogen bonds, two hydrogen bonds turning into covalent bonds, and double bonds moving ...


8

Chop the body into smaller pieces, using a sturdy butcher axe. Use a pressurized stainless steel autoclave (preferable with stirrer) or comparable professional kitchen equipment, suspend the pieces in concentrated $\ce{NaOH}$ and apply heat! Cool down, release pressure and check. Saponification of body fats releases fatty acids that might form protective ...


8

The basic idea is sound, and is used to some degree; however, there are significant difficulties inherent in "tailoring" a chemical to selectively target certain organisms and not others. There are three things that a chemical can do that make it toxic to cellular life: Rip some vital chemical to shreds. Chlorine and other light halogens (fluorine, iodine)...


8

Yes, such substitutions are indeed possible and can possibly happen. This being the case, is it possible to substitute one important element from an object or system, for instance the calcium in our bones, with another element from its respective column, such as strontium. There are some strontium based supplements on the market (strontium citrate, ...


8

Click chemistry is a term coined by K.B. Sharpless in 2001. The original paper "Click Chemistry: Diverse Chemical Function from a Few Good Reactions."[1] describes a set of very well working reactions with certain characteristics that, in general, can be used to join molecules together. Such characteristics are for example: wide in scope high rates and ...


8

The metabolism of living creatures keeps the dynamic equilibrium of their $\ce{^{14}C/^{12}C}$ ratio with the enviromental $\ce{^{14}C/^{12}C}$ ratio via photosynthesis, breath, food and excrements. It is not just about one time building, but also about continuous recycling of the body content. Such an equilibrium means continuous resetting of the $t=0$ ...


7

Aspartame is one of the most well studied food additives there is. It seems to be controversial in the same way that evolution is—scientific research is overwhelmingly on the side of the substance being safe to consume, even at very high levels, but a Google search on it brings up things like "Aspartame is, by Far, the Most Dangerous Substance on the Market ...


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