The study of chemistry within the scope of biology: the compounds that occur and the reactions involving them in living organisms.

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7 views

Is galvinoxyl antioxidant assay possible using NMR spectroscopy?

I would like to perform an antioxidant assay using the galvinoxyl protocol. The protocol states that we need EPR spectroscopy, but only NMR spectroscopy is available at my institution. Is there an ...
13
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1answer
377 views

Solubility of DNA in water

This would seem to be an easy to answer question, but I was unable to find an answer (in g/L) for generic double-stranded DNA or plasmid neither on Google nor on BioNumbers. I would expect the ...
2
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1answer
267 views

What is the biochemical reason for mental fatigue?

Is it known exactly why the brain needs sleep? What's dropping low / going high when we experience mental fatigue? I can see why low glucose could result in mental fatigue, are other reasons known?
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1answer
2k views

Why does hair turn grey or white, and why does it happen later for some?

The question is pretty simple: what is happening molecularly when hair turns grey or white? I would imagine that it is due to the lack of a particular compound. I'm also interested in why some ...
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0answers
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How to conduct a new protocol for antibody sequencing? [closed]

I will start a new protocol for antibody sequencing. Does anyone has already did it? What's the right procedure to do it? I don't know what dilution to do with my experiment.
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0answers
23 views

What happens when we eat excess fat?

The fats in our body are stored in fat cells. When we over eat fats does the size of our fat cells increase, are more fat cells generated, or do we "throw out" excess fat?
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1answer
179 views

Does the cell internal temperature changes in response to a change in external temperature?

Background Some species are homeotherm (internal temperature is not affected by a change in external temperature) and some are poikilotherm (internal temperature changes in response to external ...
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2answers
56 views

How to read this diagram?

I have diagram of oxidative decarboxylation of pyruvate pathway. The pathway is between glycolisis and Krebs cycle. How to read this diagram? This excerpt from Harper's Illustrated Biochemistry, ...
4
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2answers
51 views

Energy released during the production of ATP?

When glucose is used during aerobic and anaerobic exercise, how much energy is expended or required? During aerobic exercise: $C_6H_{12}O_6 + 6 O_2 \to ATP + H_2O + 6 CO_2$ + energy During ...
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1answer
42 views

Does pH affect Michaelis constant?

I have been trying to confirm the Km of a substrate (which is 34 +/- 4 mM). This value was obtained in 50 mM MOPS, pH 6.3. I conducted my kinetics assay in a buffer of pH 7 and obtained a Km value in ...
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0answers
11 views

Biomolecule , DNA-RNA difference [duplicate]

Why is that a RNA has uracil in place of thymine? RNA could have thymine bases but it has uracil ? What is the reason for the presence of uracil there ?
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0answers
22 views

How can we determine the polarity of fat molecules?

I'm trying to solve a question in a biochemistry quiz, which is asking for classifying a set of lipidic derivatives, by increasing polarity. Unfortunately, we didn't cover the classification of ...
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0answers
51 views

Ways to fight black mold

Is it possible to introduce a microorganism to a colony of black mold that will kill off the black mold entirely and permanently? Is there a common microorganism that likes to eat them and is harmless ...
1
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1answer
22 views

How is Glycophorin A and straphylococcal related to Escherichia coli and what does readily purified mean in this context?

I am reviewing the paper "Glycophorin A Dimerization Is Driven by Specific Interactions between Transmembrane Alpha-Helices." There is a statement in the abstract which I don't understand: "The ...
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2answers
64 views

Binding of Multivalent Antibody to mutiple epitopes?

A multivalent antibody molecule such as Immunoglobulin M Immunoglobulin A etc bind to more than one antigens or epitopes but I am confused about that wheather these multivalent antibodies bind to ...
4
votes
3answers
124 views

Phospholipid Bilayer structural reversal

What would happen if the phospholipids in the phospholipid bi-layer were reversed, the fatty acid tails now facing outwards and the phosphate heads facing inwards? I'm assuming this will not affect ...
3
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1answer
39 views

How do single-celled predators chase other cells?

From my understanding, single celled organisms have been seen avoiding, and chasing, potential food or other organisms. How do they accomplish this? They do not have eyes or ears or a nervous system. ...
2
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1answer
118 views

Why are nitrogenous bases of DNA hydrophobic if they can hydrogen bond?

Why are nitrogenous bases of DNA hydrophobic if they can hydrogen bond? Is it that they are only relatively hydrophobic? This forum explains it but does not give an example of the structure.
2
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1answer
83 views

What biological processes can affect the temperature of the shadow a tree casts?

Assuming two trees have similar shape and leaf coverage, could differences in the biological processes among them lead to differences in the temperature of the shadow they cast? What biological ...
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4answers
5k views

Why we have no enzyme to digest cellulose?

As we know, cellulose is the most abundant polysaccharide in nature. Why don't we have any enzyme to digest cellulose?
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1answer
109 views

Background correction when reading ELISA with TMB substrate

I'm doing some ELISA development, and I'd like some justification/best practices for background correction. I'm using a horseradish-peroxidase (HRP) detection system along with a TMB substrate and an ...
6
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2answers
537 views

Are there any multicellular forms of life which exist without consuming other forms of life in some manner?

The title is the question. If additional specificity is needed I will add clarification here. Are there any multicellular forms of life which exist without requiring the consumption (destruction) of ...
6
votes
3answers
213 views

Is NADPH salt still usable after an hour at room temperature?

I accidentally left a delivery of NADPH Tetrasodium Salt (Santa Cruz Biotechnology) at room temperature for a little over half an hour. In addition, when I opened up the package, I briefly held the ...
2
votes
2answers
123 views

How does a smoker's finger or mustache get yellowish by nicotine?

Tobacco use is the leading cause of preventable death around the world.$\ce{^1}$ The stain is considered as a "tell-tale" sign for identifying smokers. Multiple materials stated that it's due to ...
3
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0answers
35 views

What Chemical Trigger Causes Ectomycorrhiza To Change From Asexual To Sexual?

I am searching for the catalyst behind the change of asexual to sexual ectomycorrhiza when symbiosis with a tree root is formed. As ectomycorrhiza attaches itself to a root, they form a relationship ...
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1answer
24 views

Finding a reaction from a KEGG map

I have come across a map and a part of it looks like this: Now I have not been able to locate the reaction that converts alpha D-Glucose to Glucono-1,5-lactone but was successfully able to locate ...
7
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1answer
138 views

Why is leucine amino acid used the most in proteins and tryptophan the least?

The amino acid leucine, is used in proteins more than others. Leucine with 9.1 percent (its average in more than 1.150 different proteins) is used most and tryptophan with 1.4 percent is used less ...
2
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1answer
27 views

dAT joining: please define

I came across a reference to dAT joining in my reading of Genentech by Sally Hughes. The technique is described in passing as a technique for joining DNA fragments used around the late sixties to ...
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0answers
14 views

Why does a limb sting when it “falls asleep”? [duplicate]

Closely related to this question, but unanswered other than @Matthew-piziak providing a description and link that says: What is Paresthesia? Paresthesia refers to a burning or prickling sensation ...
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0answers
16 views

Reversible biological module in KEGG

Considering the kegg module M00570 The pathway looks like this: ...
7
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3answers
264 views

Why don't phospholipid bilayers dissolve?

I just started learning about the structure and composition of cell's membrane and there is something that I fail to understand. The membrane is composed of a phospholipid bilayer. The phospholipid ...
2
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0answers
33 views

Textbook for quantitative biochemistry with thermodynamics, as an alternative to Voet, Voet & Pratt (Fundamentals of Biochemistry)?

I'm looking for a great textbook on biochemistry that covers core topics: relevant aspects of thermodynamics, reaction kinetics, metabolism (e.g. krebs cycle, respiration, etc.). Ideally it would also ...
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2answers
46 views

Does ATP hydrolysis reaction have a high or low activation energy?

I was recently studying about ATP and how it functions as an energy carrier to all biological processes; however, I came across a confusing and paradoxical statement from two sources: (at 7:36) and ...
0
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1answer
28 views

What does “each pathway define an independent genotype” mean?

In a section of this paper. However, if the question of independency is posed in the form: “Does each pathway shown define an independent genotype?,” then each of these three pathways is ...
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2answers
7k views

Does mixing alcoholic drinks really make you more drunk?

There is plenty of anecdotal evidence ("beer after wine and you'll feel fine, wine after beer will make you feel queer") that mixing alcoholic drink types leads to a stronger effect, but I can't find ...
4
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1answer
50 views

How does botulinum toxin enter the blood stream from the digestive tract?

To my understanding, large polypeptides such as botulinum toxin cannot pass the intestinal lining intact. How, then, can it enter the bloodstream and cause botulism poisoning?
2
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1answer
34 views

Why is there a compound highlighted in red in a KEGG Module search?

Considering the following module: http://www.kegg.jp/kegg-bin/show_module?M00115+C00003 why is the compound C00003 marked in red?
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1answer
25 views

Presence of reaction module in bacteria but not in Eukaryotas (human)

From the statistics page, I found that the Module-M00008 is present only in bacteria and not Eukaryotes. Why so? I noticed that all the compounds necessary or the reaction are present in human body ...
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0answers
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Can I explain the kinetics of a ligand looking at the ligand-protein co-structure?

Can I explain the kinetics of a ligand binding to a target protein (association and dissociation rates) by looking at the protein-ligand co-structure? Editing my question after a few comments: I ...
3
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2answers
58 views

Energy transformations in chemiosmosis and ATP synthase

In terms of energy, how does chemiosmosis drive ATP synthase? How does electrical energy turn into mechanical energy and then into chemical energy? Would the movement of $H^+$ be considered passive ...
3
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2answers
53 views

Why do negative ions flow into a cell in an inhibitory synapse, even though a neuron has a negative resting potential?

In my spare time I have been reading an introductory Psychology textbook and this question came to my mind after reading about action potentials. I have no previous knowledge in chemistry so if I do ...
1
vote
1answer
35 views

Can Nanodiscs be used to study membrane energetics?

Nanodiscs have changed they way we can study the structures, insertion, and functions of transmembrane proteins. Below is an image of a nanodisc bilayer. The key difference, as far as I can tell, ...
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0answers
17 views

Differences in structural target for LPS detection by LAL and MD-2/TLR4

I remember there being a significant difference in the pathogen-associated molecular patterns (PAMPs) used for detection of lipopolysaccharide (LPS) by mammalian cells and the Limulus amoebocyte ...
3
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2answers
124 views

Is there a short-term, very strong anesthetic, which can be blocked/delayed by other substances?

Question migrated from World Building SE. (For fictional use only, of course :) ) I am looking for an anasthetic which fulfills the following criteria: very strong effect, induces a comatose state ...
4
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4answers
227 views

Why can't you just take a vitamin? Why you need a healthy diet on top of that?

From what I understand, your body needs certain amounts of vitamins and minerals to maintain health. Why can't we just take enough pills to obtain these vitamins and minerals?
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2answers
66 views

Need some good resources to learn about Protein function and structure

I'm taking a course on biochemistry at edx. Since I'm a computer science student, I'm having some trouble in understanding many biochemical concepts. While the first module was just fine, I found the ...
7
votes
1answer
54 views

Why do humans require vitamin B12 supplementation while herbivores do not?

This question came about from reading the comments of this (very unclear) question, which the author did not properly clarify. Vegans are often recommended to take vitamin B12 supplements, as the ...
4
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2answers
185 views

How do you store membrane proteins?

We're producing some membrane proteins and they aren't amenable to freeze thaws even when we add glycerol. The proteins are solubilized in detergent above the cmc so they should be in micelle form in ...
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2answers
112 views

How does decreasing surface tension of lipids help to emulsify them?

According to my chemistry book, water has higher surface tension than lipids. But in my biology book it is written that "the gall forms an emulsion of water and lipids by lowering the lipid's surface ...