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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110 views

Plants without bacteria? is it theoretically possible?

I know from school, that all live on the Earth need bacteria as low-level "machines" that break down/extract/convert/produce chemical elements and combinations, other high-level organisms needed. But ...
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2answers
162 views

Does the Urea Cycle exist in invertebrates?

Do invertebrates (like Drosophila and C.elegans) have a urea cycle?
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0answers
30 views

Can the sulphur content of biological material be reliably calculated from fat, fibre and protein contents (Weender Analysis)?

An often-used analysis of feedstocks for lifestocks is the Weender analysis, which basically divides the volatile solid content into fats, fibre and protein, as well as N-free matter. I found no ...
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2answers
394 views

Why does Glutamine have the symbol Q?

Spent a half hour googling this and the best I could find was this: Now for some rhymes: Arginine = R. R we having fun yet? Asparagine = N The kNights of Ne say "Ne". Glutamine is a cute ...
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1answer
61 views

Can we use Acetyl Phosphate instead of Acetyl CoA in TCA?

I am thinking Citric Acid cycle and activation of the end parts of Acetyl and alfa-ketoglutarate. Let's consider only now Acetyl to make things simpler. I have tried to explain the thing by symmetry ...
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2answers
1k views

Very high 260/230 absorbance ratio of an RNA sample

After my most recent RNA extraction, the RNA samples had very high 260/230 absorbance ratios, (ranging from 5 to 25). I've never gotten numbers like this and I know the ratio is supposed to be ~2 in ...
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1answer
3k views

Melting point of a fatty acid?

What factors determine the melting point of a fatty acid? Chain length The number of methylene group The ionized state of the fatty acid Its degree of saponification Its ability to alter the ...
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2answers
2k views

Does ethanol destroy RNase?

I've gotten conflicting advice on this: some people believe one can remove RNase contamination simply by spraying the bench, pipettes, gloves, etc. with ethanol. Others think ethanol does not destroy ...
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1answer
113 views

How to wash the column during protein purification with GST tag?

I have been working with GST tagged proteins for the last 4 years and after loading the cell lysate into the column I was washing it with 20-30 column volumes of PBS and sometimes my proteins were ...
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2answers
1k views

Simple diffusion of lipid-soluble molecules through phospholipid bilayer — does anything get “stuck” in transit?

It's a pretty elementary concept, and when I first learned of it I don't think I had the foundations to even think of such a question, but I found myself the other day thinking about the amphipathic ...
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2answers
697 views

Why is absorbance at 280 nm for protein solution going up when I measure repeatedly?

I have been measuring my protein solutions' concentrations by diluting them in water 20 fold with a final volume of 100 uL and then measuring the absorbances of these solutions in 96 well plates with ...
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1answer
145 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
606 views

Why is second pKa value of phosphoric acid different across different sources?

Am I missing something very fundamental here for phosphoric acid's second pKa value? I check the Wikipedia page and these are the values: (1) 2.148, (2) 7.198, (3) 12.377 Then I check Sigma-Aldrich ...
3
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2answers
187 views

What software is there available for Quantitative structure–activity relationship (QSAR) pharmacological studies?

QSAR modelling in pharmacology basically hangs on using mathematical modelling to approximate the effects different molecules will have on various pharmacological targets. I would like to know what ...
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0answers
75 views

Why does trans fat decrease hdl's?

I understand that cis fats increases hdl's, and unsaturated fat increases ldl's, but trans fat increases hdl's and it decreases ldl's. Why does trans fat do this?
11
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1answer
459 views

Why do we feel tired if we sleep excessively?

When we eat, finally we feel full. I know which mechanism causes the sensation of being full. But when we sleep excessively we often still want more sleep. Why does this happen? Is there a mechanism ...
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0answers
29 views

Glutamine analysis

I use to run a method to analyse all the aminoacids in a food sample. For that I have to hydrololyse the sample and in the last stage of the method I read the amino acids with a ion exchange ...
4
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1answer
118 views

How is respiration an unbalanced equation

The equation for respiration is C6H12O6+6O2→6CO2+6H2O+36ATP. The chemical formula for ATP is C10H16N5O13P3. How is this possible, since it violates the law of conservation of mass because it is ...
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1answer
124 views

Can jellyfish improve Black Sea environment?

According to this study, cited by many popular science magazines, jellyfish and other, smaller animals can contribute to the vertical ocean stir as much as currents do. Black Sea chemistry and ...
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1answer
241 views

How do multiple replication forks function without 'colliding', and what is the benefit of this method?

I'm currently reading a little about DNA replication, and have come accross the following statement; Replication starts from a fixed point and is bi-directional ... In Eukaryotes, there are ...
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0answers
49 views

Solid phase use in HIV rapid tests

I have another question in regards to my HIV test research. The rapid tests like Orasures Oraquick contains a strip of synthetic peptides that are used to represent proteins found in the envelope ...
3
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0answers
22 views

Does Doxylamine have any Influence on the Monoaminergic System?

Does doxylamine have any affects on the monoaminergic system? Specifically I am interested in adrenergic or serotonergic activity but additional information on its dopaminergic activity won't hurt ...
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1answer
58 views

Which Enzymes are Responsible for the Biodegradation of Noladin Ether?

Which enzymes degrade the CB1-specific endogenous cannabinoid 2-arachidonyl glyceryl ether? (Noladin ether)
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1answer
36 views

Which Enzymes are Responsible for the Biodegradation of Beta-endorphin?

Which enzymes are responsible for the biodegradation of the endogenous opioid peptide, beta-endorphin?
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1answer
83 views

Good place to ask health based questions? [closed]

I like the development of biology.stackexchange.com, but it is still in an early stage and far from perfection. While we develop it further, could you guys help me finding places to ask questions ...
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2answers
795 views

Bacterial cell lysis - what solution to use?

I am trying to determine how quickly detergents act on bacterial cells (cell lysis). I would like to compare some detergents at difference concentrations for bacteriolytic activity. I don’t care about ...
6
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1answer
117 views

Why does getting certain chemicals in cuts hurt?

More specifically, shampoo. What are the mechanics of detecting a noxious chemical stimulus in terms of which receptors recognise what, how do they do it, and how is this information relayed to the ...
3
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1answer
117 views

Can compounds be predicted from Polyketide synthases gene clusters?

I've seen a few talks on the subject. From a gene cluster, there is some decent ability to determine which domains contribute to certain functional groups in the final metabolites. It sounds like this ...
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1answer
103 views

When running a gel, what could cause a standard to run “faster” than usual?

We are running a gel on the products of a restriction digest to determine the size of an insert. We know the vector backbone size should be ~2.9kb; however, the standard appears to be running too ...
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3answers
1k views

Where does the 'C' in exhaled CO2 mostly come from?

When a human being exhales $CO_2$, what is, by the numbers, the main source of carbon atoms exiting the body in this way? I mean what class of cells, or which tissues are the biggest on a pie chart of ...
11
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1answer
1k views

How much energy does human body fat contain?

I have been reading the Wikipedia article about food energy, but as I'm not a biologist, I don't really understand it properly, so I came here to ask you guys. My question is: If a human body needs X ...
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1answer
115 views

Is eating salt dangerous for the brain?

I read somewhere that eating a lot of salt will raise blood pressure, which will in turn damage brain tissue. This is because water molecules gather around salt ions, thus making it harder for the ...
4
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1answer
136 views

How does ethanol interact with insulin?

I know that ethanol increases insulin secretion--could someone explain why? All I have found till now is experimental data analyses. I am interested in mechanism of alcohol consumption.
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0answers
50 views

Do humans have chemosensors for nutrients or chemicals?

I'm reading about chemoreceptors on Wikipedia, and see that the typical ones are mentioned: taste, smell, co2. I would like to learn more about the other kinds of chemoreceptors that humans may ...
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2answers
299 views

Why do living organisms replicate itself or procreate

Why do living organisms spontaneously replicate itself or "procreate" (my understanding is that it does). From a uni-cellular and micro-organism point of view. Is there some sort of stimulant in the ...
2
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0answers
141 views

Virucides - Herbal and otherwise, for HHV6 type virus or any inner-cell virus

Does anyone know where I can find a reliable list of virucides (not anti-virus) that can be used by humans? This virucide must be able to affect viruses that are already inside the cells. St John's ...
6
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1answer
250 views

Determining if a specific proline is cis or trans in the protein?

While peptide bonds usually adopt the trans conformation, peptide bonds to proline can exist in either cis or trans conformation. The isomerization between cis and trans is slow, and has been shown to ...
6
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1answer
2k views

HDL- and LDL-cholesterol

Why exactly are HDL-cholesterols good for us and LDL-cholesterols not. I know LDL-cholesterols cause Atherosclerosis and that HDL-cholesterols removes the excess of LDL-cholesterols, but from a ...
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1answer
353 views

How to Design an siRNA Experiment?

I'm going to undertake an siRNA experiment soon, but I have only read about them. I want to address the role an enzyme plays in processing a protein. From what I understand, I will need to pick two ...
2
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1answer
57 views

Diet of free-range herbivores

Giving minimal credence to estimates in popular media of the average biomass of insects/arachnids, etc. in an acre of land, it seems that a "free-range" cow (I don't mean to pick on cows) might be ...
4
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1answer
221 views

What is the molecular basis of hangovers?

Well, most of us have experienced the wonderful feeling of the dreaded hangover. How does it work exactly? I imagine it has something to do with dehydration but what are the underlying mechanisms? ...
6
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1answer
305 views

$S_{0.5}$ vs $K_m$ values in enzyme kinetics

What is the difference between $S_{0.5}$ values and $K_m$ values in enzyme kinetics?
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1answer
115 views

What are the biochemical interactions between human body and Polyethylene?

Our waterways and oceans are showing increased levels of plastic contamination. These plastics are breaking down into smaller pieces. When one goes to the beach and plays in the surf they often ...
5
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1answer
341 views

Using ion-exchange chromatography to purify DNA from a cell extract - Is DNA more negatively charged then RNA?

When applying this method we have a glass or plastic column of resin which is positively charged. Then we pour cell extract into the column in order to capture the negatively charged particles which ...
4
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1answer
103 views

Are there any websites offering graphs for the light absorption of different enzymes?

I have found graphs for the light absorption of water, haemoglobin, lipids, melanin, etc., but I am having a hard time finding graphs about enzymes. Are there any websites or other reference sources ...
4
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1answer
875 views

Conversion rate of topical Retinol to Retinoic Acid (Tretinoin)?

I'm wondering if someone out there has more information than me. Retinoids have well known metabolic pathways in vivo, and it's usually something like: ...
7
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2answers
78 views

Should we be looking for extra-terrestrial life on comets?

I have just read What elements are a possible basis for life? and I find myself wondering whether instead of seeking advanced life-forms at remote locales a La SETI, and perhaps fundamentally ...
7
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1answer
675 views

Does drinking coffee have negative effects?

From what I collected, coffee is a magical potion that lets you feel energetic, and essentially not-sleepy. But are there any tradeoffs? I mean, if it was so beneficial, wouldn't the human body ...
4
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2answers
3k views

DNA as an acid? [duplicate]

Possible Duplicate: Does DNA react in all of the ways most other acids do? Even if DNA is made up of nucleotide bases, it is said to be an acid. Why is this?
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1answer
267 views

Ammonium sulphate precipitation assay pH dependence

In general does the pH effect the precipitation, e.g. would a pH of 6 cause less precipitation than pH 7.5. Or are they unrelated?