Questions tagged [chemical-biology]

Questions about the application of chemistry to interrogate and modify biological systems and processes.

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18 views

How did examination of bristlecone pines change theories about the Bronze Age? [closed]

The recent Jan 20, 2020 issue of The New Yorker features Alex Ross' publication The Past and the Future of the Earth’s Oldest Trees. The author states (or, around 4min30 of the audio link below the ...
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247 views

How can an Organic chemist know the chemical formula of a natural product she isolated from an organism? [closed]

As a non scientist I several times wondered how can an Organic chemist successfully isolate a single molecule which a natural product of an organism; Whether a plant-part/mushroom-part/algae-part or a ...
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Oxidative phosphorylation analogue

Does the salt bridge in galvanic cells resemble the ATP pump in the inner mitochondrial membrane? And if yes than did someone use this pH difference in harvesting this energy?
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Why is it important to remove the used up electrons in oxidative phosphorylation?

I get that oxygen is the terminal electron acceptor in oxidative phosphorylation. But why is it essential to accept these electrons and remove them as $\ce{H2O}?$ Oxygen is essential for cellular ...
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36 views

Is there a software that can predict the shape of a custom protein, given its amino acid sequence?

I know that the internet is full of enzyme and protein simulators which can show active site and 3D structure (like bioblender), but the problem with these programs is that they use predefined ...
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A question about thiamine [closed]

How does the the nitrogen of thiazole in thiamine acquire a positive charge without being stabilized by another negative charge or by being a salt of an anion?
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A question about nicotinamide adenine dinucleotide

In the structure of NAD+, why does the nitrogen of pyridine bind covalently to the the first carbon of glucose while the anion stabilizing the nicotine amide ion is the phosphate group? In other words,...
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22 views

Pyridinium ion in inositol nicotinate

I have read about inositol nicotinate which is used as a medication for deficiency in vitamin B-3. I think that if acetic acid was applied to this medication it would form pyridinium ion and acetate ...
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375 views

How does one tell (or conclude) if a substance is carcinogenic?

It's common to read statements like: Tetrachloroethene ($\ce{CCl2=CCl2}$) was earlier used as a solvent for dry cleaning, but since it contaminated ground water and is a suspected carcinogen, ...
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Stable physiological buffer to make NAD+ solution

I was wondering what would be the most stable physiological buffer for nicotinamide adenine dinucleotide (NAD+), for potential storage as frozen aliquots - 6 months stability or around there would be ...
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1answer
71 views

Antiseptic role of a kerosene

I remember my grandmother putting lots of kerosene on my wound when I was kid and got a huge cut on my finger, as there was no health facility around. Want to confirm if chemists do agree on ...
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1answer
38 views

what wavelength should I use to measure the transmittance of iodine colouring? [closed]

I am doing an experiment on how pH buffers may affect amylase's break down of starch into glucose in a starch solution. I am using iodine reagent to identify how much starch is left after amylase is ...
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Why does radiocarbon dating only work in nonliving creatures? [duplicate]

I understand how carbon dating works, though I do not understand why it doesn't happen while a creature is living. Because while we are alive we still have carbon 14 in us, so shouldn't it work?
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Epoxy-silane-coated glass applications or the preparation or quality control for the silanized glass

The task is to make myself (3-Glycidyloxypropyl)trimethoxysilane (GMPTS for short) covered microscope slides to immobilize antibodies. Each time I cover the freshly prepared slide with Ab, I get ...
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40 views

transpiration of trees and the cooling of the air

The change from the liquid state of water to the water vapor requires a large latent heat to loosen the hydrogen bonds. The process of transpiration in the plant involves exactly this change of state. ...
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22 views

Fat polymerization vs hydrolysis and temperature change

I have an experiment on fats that I have to do in a few hours and I am very lost between fat/oil (lipid) polymerization due to high temperatures and hydrolysis. It appears that both result in the ...
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31 views

How to compute the number of ATP molecules that can be produced from breaking down an unsaturated free fatty acid?

From studying $\beta$-oxidation of free fatty acids, I've learned how to compute for the ATP equivalence of even-chain and odd-chain free fatty acids. What really bothers me now is how to compute for ...
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1answer
775 views

DNA pairs (adenine-thymine, guanine-cytosine) [closed]

Well I was wondering why adenine pairs with thymine and cytosine pairs with guanine. From those pictures: Thymine has the lowest acidity and adenine has the biggest acidity. So it is logical that ...
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1answer
65 views

Is sugar in mead different from “regular sugar”?

My understanding of the process of making mead is that you combine honey, yeast and water in an anaerobic environment. The yeast-bacteria ferments the sugar in the honey and produces ethanol (among ...
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1answer
246 views

what is the structure of bamboo kun?

There are claims that the bamboo fiber has inherent antibacterial properties due to "bamboo kun". However I could not find anywhere what is the chemical composition of this "bamboo kun" and also no ...
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47 views

Increasing concentration of acetylcholine via SPE

I am trying to increase the final yield of acetylcholine (ACh) in my biofluid samples. I need to get the yield high enough for high confidence annotation of ACh (currently all I can really say is that ...
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80 views

What does the formula (CH2O)106(NH3)16H3PO4 represent?

The molecular formula $\ce{(CH2O)106(NH3)16H3PO4}$ appears in the wikipedia entry for "anoxic bodies of water". A quick search suggests that it represents the product of photosynthesis, or the ...
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Modification of Janus nanoparticles [closed]

I would like to synthesis gold/polyacrylic acid (PAA) Janus nanoparticles in solution. Any ideas how I can functionalize gold with a photosensitizer and PAA with an antibody so that there would be no ...
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2answers
124 views

Why do chiral biological molecules only exist as one enantiomer? Does it have any advantage?

Why is it that chiral biological molecules are enantiomerically pure? The other enantiomer would have the same reactivity, and the only difference is their angle of rotation of plane polarized light. ...
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1answer
115 views

What are glues/adhesives for cardboard boxes/crates made of?

Open cardboard boxes/crates, often for foodstuffs, are often glued to hold their shape. What is the glue/adhesive made of? I ask to know if it is biodegradable, such that it is suitable for ...
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15 views

Does N-linked glycoslation inhibition increase or decrease par-2 recepto aar activity

Hello guys I need some clarification, i know that melanosome transfer to keratinocytes is regulated in part by par-2, and this receptor is activated by trypsin, sligrl and to a lesser degree tryptase. ...
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1answer
58 views

Can air conditioning cause urine smell?

On rainy days there is a strong urin smell on trains in Tokyo. I suspect this smell comes from ammonia. On Wikipedia I read: Ammonia and ammonium salts are also found in small quantities in ...
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50 views

How to determine toxicity of a substance? [closed]

I often read description of various compounds or elements as being poisonous. Now I know that through experience we have discovered the toxicity of various substances like lead, chlorine or phosgene ...
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27 views

Why do foraminifera use less magnesium in their shells when the water is cold?

When scientists study ancient seabed cores, they say they can judge the temperature of the water in the past by analyzing the magnesium to calcium ratio in foraminifera shells (both in the form of ...
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1answer
625 views

How are glycosidic linkages formed?

Consider glycosidic linkages in disaccharides. I know a condensation reaction occurs, with the loss of water. But which OH is lost? The O in the linkage belongs to which monosaccharide? Example: ...
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Purifying cysteine containing peptides

I would like to purify my peptide having cysteine residue by using HPLC. It is known that thiol containing peptides undergo oxidation and form disulfide linkages. In order to prevent it I used proper ...
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1answer
181 views

Why is molybdenum that important in inorganic synthesis as well as biosynthesis of ammonia?

We know that Mo (Molybdenum ) is used as a catalyst for Haber's process, during synthesis of Ammonia from Nitrogen. Again, in biological systems, Nitrogen fixation (ALSO forming Ammonia from Nitrogen)...
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What provides the energy allowing membrane proteins to facilitate diffusion across the membrane?

We know that facilitated diffusion requires no energy. But the transport proteins, when bind to a molecule from ECF (extra-cellular face) , the proteins rotate and deliver the molecule into ICF (...
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464 views

How can I prepare a PBS (Phosphate Buffer Solution)? pH=7.4 [closed]

Phosphate-buffered saline (abbreviated PBS) is a buffer solution commonly used in biological research. It is a water-based salt solution containing disodium hydrogen phosphate, sodium chloride and, in ...
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54 views

How to recreate bioluminescence in fireflies in a lab?

I have several mg/mL of D-luciferin, luciferase (firefly), ATP solution (25 mmol) and MgSO4 (for the mg2+ ions). The experiment has to be done in cuvettes of 2,5 mL (if I get any results, it will be ...
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448 views

How does existence of alpha and beta form of glucose prove that it exists as a cyclic structure

My book says that Glucose is found to exist in two different crystalline forms which are named as $\alpha$ and $\beta$. Next it says that This behaviour could not be explained by the open ...
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64 views

Oil + UV radiation = cholecalciferol?

According to a web site about health (Antranik): The oil that naturally comes from our skin is a type of cholesterol. Whenever we stand under direct sunlight, the ultraviolet rays react with ...
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3k views

Is there any difference between isotonic and isosmotic solution?

Is there any difference between isotonic and isosmotic solution? Can we say isotonic solution do not show osmosis because they have same osmotic pressure?
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1answer
61 views

What would happen if we had a different kind of metal in our bloodstream? [closed]

It is a common fact that we have iron in our blood. But what if we had something different in its place? Like instead of iron what if it was copper, or silver, or what if we had gold in our blood ...
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49 views

Opening the imidazoline ring in tolazoline

Hello. I was studying about the alkaline ring opening or purines. While doing research, i came across this compound. This got me thinking if we can use the same procedure to open the imidazoline ring ...
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67 views

A liquid that forms a surface membrane that prevents evaporation but allows oxygen to pass through

I'm a biologist. I have a water solution with living cells in a tiny well (10 um). I need to keep the solution from evaporating for several days in a warm incubator. I'm looking for a liquid to place ...
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54 views

How many natural products are there in existence? [closed]

Hi I'm doing a project on natural products and I'm wondering if somewhere there is at least an estimated number of how many exist? If this exists somewhere can you please provide a reference. ...
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When the present state of knowledge concerning central noradrenergic transmission was established?

Some time ago I began to search for descriptions of the mechanisms responsible for the regulation of noradrenergic transmission in the central nervous system of man and to my great surprise the most ...
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288 views

Solving two electron integral numerically

Is there any software package in python or C to evaluate two electron integral repulsion integral in quantum chemistry of atoms. I am trying to solve the helium atom by constructing many body basis....
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1answer
67 views

C-4 oxidation of octanoic acid to 4-oxooctanoic acid

I am leading a project in which I am attempting to synthesize 4-oxooctanoic acid in a (mostly) biological pathway. Currently, I have reached a dead-end. I have a way to create octanoic acid through ...
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1answer
40 views

Enzyme Kinetics two enzymes in complex with one substrate

Given an enzyme reaction where two enzymes are required to form the complex, for example $\ce{2E +S-> E3S->2E +P}$, how would I calculate complex concentration assuming steady state ...
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1answer
193 views

Why does the structure of haemoglobin change when the ferrous ion changes to ferric ion?

It is said that $\ce{Fe^2+}$ can bind oxygen while $\ce{Fe^3+}$ cannot. Why is that so? $\ce{Fe^3+}$ has an extra electron, it could bind more easily to the oxygen. And how and why does the structure ...
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Question about the composition of a 1902 non-polarisable electrode diagram by Jagadis Bose

In his work, "Response in The Living and Non-living" (1902); page 6, Jagadis Bose describes a method for detecting nerve response. He explains that he uses iso-electric contacts with no current in the ...
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2k views

Is Biotin water-soluble or fat soluble?

Vitamin $\ce{B_7}$ or Biotin is a member of the vitamin B complex. Members of the vitamin B complex are usually known to be water soluble. However, this webpage mentions that biotin is water soluble. ...
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102 views

Modification to improve antibacterial activity

I have difficulties with part b). For C, it's clear to make a bulky dimethoxybenzene group in order to block the C=O group from reacting with b-lactamase. However, in A, how does the structure of ...