The function of chemistry within the scope of biology; the study of the compounds that occur, and the reactions involving them, in living organisms.
2
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2answers
81 views
Why do neurones use chemical signalling at synaptic junctions?
Problem. When a neurone fires, it sends an electrical signal that jumps down the axon via the nodes of Ranvier very rapidly. At a synaptic junction, chemical brownian diffusion signalling with ...
15
votes
4answers
703 views
Why are there exactly four nucleobases in DNA?
Does someone know why DNA is composed of four nucleobases? In particular, is there an explanation for the number? Why four and not two, or eight?
1
vote
2answers
70 views
PEG-silane treatment: why incubate for 18 hours at 60 degrees Celsius?
I am conducting a biochemistry-related experiment and I have been unable to understand a step which is commonly performed.
My aim in this step is to apply a PEG (Polyethylene glycol) silane layer.
...
1
vote
0answers
20 views
Relationship between biomass and net primary productivity
I want to do validation on simulated net primary productivity. But I don't have measured NPP data, Eddy covariance flux measurement data. I have only field measurement biomass data. So can I directly ...
5
votes
1answer
107 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 ...
0
votes
0answers
20 views
How do cells slowly degrade 5,5'-dibromo-4,4'-dichloro-indigo?
5,5'-dibromo-4,4'-dichloro-indigo is the product of X-gal cleavage, often used as a reporter with B-galactosidase. I've made the (unreferenced) observation that it seems as though the blue product ...
2
votes
3answers
47 views
Histidine aromaticity
I understand that the imidazole ring in histidine is aromatic. I also realize that it retains it's aromaticity when protonated.
I am wondering why it is not mentioned at all in basic text books such ...
1
vote
1answer
40 views
What is the use of futile reaction cycling such as Fruc-P to Fruc-BP?
One rate-limiting step of glycolysis is the conversion of Fructose-Phosphate (Fruc-P) to Fructose-Bisphosphate (Fruc-BP), catalysed by Phosphofructokinase (PFK). The reaction involves hydrolysing one ...
1
vote
1answer
79 views
Chemical structure prediction
I'd like to do chemical structure prediction using a known molecule formulas. I'm familiar with de novo protein structure prediction, but are there any programs which will go from formula to structure ...
1
vote
1answer
34 views
How do animals/plants change for each season?
The question pretty much sums it up. How do animals/plants change for each: Spring, Summer, Autumn, and Winter?
A detailed explanation on distinct behaviour and appearance changes would be nice.
2
votes
3answers
46 views
What biochemical molecule viewer allows for changes in amino acids and resulting tertiary structure?
I am familiar with the Jmol, Rasmol and PyMoL softwares, and was recently introduced to BioBlender. However, I am completely unaware if any of these programs (or others) are capable of loading a .pdb ...
9
votes
2answers
1k views
Why is PEG important for efficient yeast transformation?
One way to do an yeast transformation is by using lithium acetate, a single-stranded carrier DNA, and PEG (1). I was wondering why is the polyethylene glycol important for the efficient ...
2
votes
3answers
74 views
Michaelis-Menten Kinetics: Does measuring apparent Km and Vmax take into account competing reactions?
I am learning about why it is important to measure Km and Vmax for each experimental setup because measuring the "apparent" Km and Vmax includes enzyme inhibitions of which one might not be aware.
...
3
votes
1answer
37 views
What molecular processes are involved in pseudopodial extension?
I am curious as to the processes and mechanisms involved in the extension of pseudopodia in amoeba. How does the cell know and control the direction and extent of pseudopodia formation at a molecular ...
1
vote
0answers
34 views
How do omega-3 fatty acids reduce cholesterol at the molecular level?
I have heard that omega-3 fatty acids found in fish are a good way to prevent/reduce cholesterol problems.
My question is how do omega-3 fatty acids do that: what are they doing on a chemical level ...
1
vote
0answers
19 views
What is the translation termination efficiency in mammalian cells?
When I express proteins in bacteria I put at least two stop codons at the end of the gene to increase the termination efficiency. Is this the case in eukaryotic cells too? If I put a single stop codon ...
1
vote
1answer
73 views
How exactly does marijuana damage brain cells?
I've heard that THC can cause permanent damage to brain cells. I've also heard this reffered to anti drug propaganda. Another theory i've read is that temporary effects reduce intelligence but long ...
4
votes
2answers
72 views
Differences Between Protein Motifs and Protein Domains?
I am in a 300-level molecular biology class and am unclear about this concept and how to delineate motifs versus domains of proteins. Any suggestions would be much obliged.
2
votes
0answers
22 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 ...
5
votes
1answer
103 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 ...
8
votes
2answers
150 views
Solution based measurement of Solvent-Accessible Surface Area of macromolecules
The Solvent-Accessible Surface Area (SASA) is a valuable metric for looking at protein folding and protein-protein interactions. However, this measurement is typically done by calculating the SASA ...
7
votes
2answers
116 views
During famine, does the human body do anything to prioritize which organs receive nutrients?
When food is scarce, the body slows its metabolism. Are there any other systems or processes that encourage prioritization of organs?
7
votes
1answer
92 views
How Antioxidants affects Human Metabolism?
I'd like to know how antioxidants affects the human metabolism and which ones are essential for metabolism processes.
0
votes
1answer
22 views
Definition of Dye- Reduction Test?
Can some one give a simple explanation or definition on what a dye-reduction test is.
3
votes
0answers
37 views
What causes adenosine build up in the brain when awake?
Adenosine is an important hormone in sleep regulation. It is postulated that when a person is awake, there is a build up of adenosine in the brain, which inhibits the neurons in the brain, and ...
4
votes
1answer
68 views
What causes humans to be sleepy?
Is there a hormone or group of hormones that regulates when we feel sleepy late at night, or in the morning? Or is sleepiness caused by some other non-hormonal mechanism? (e.g. pure psychological, ...
33
votes
3answers
7k views
Why is uracil used in RNA rather than thymine?
What is the advantage gained by the substitution of thymine with uracil? I have read previously that it is due to thymine being "better protected" and therefore more suited to the storage role of ...
7
votes
1answer
8k views
NADH vs. NADPH: Where is each one used and why that instead of the other?
I know NADH is used in cellular respiration and NADPH is used in photosynthesis. What difference does the phosphate group make that the same one isn't or can't be used for both? Is there a greater ...
17
votes
4answers
2k views
Death because of distilled water consumption
One of my friends said that I would die if I drank distilled water (we were using it in a chemistry experiment) I gave it a go and surprisingly did not die.
I did a bit of Googling and found this
...
0
votes
0answers
56 views
What are usable Sum formulas for Proteins?
I'm looking for something like this: $C_{13}H_{25}O_7N_3S$
. Obviously it's not about knowing the exact shape or composition of a specific protein, but knowing the relative contents of major chemical ...
0
votes
0answers
47 views
What metabolite intermediate will accumulate in a mammalian cell-free extracts capable of glycolysis if lactate dehydrogenase is inhibited? [closed]
I know the reaction proceeds as follows:
Pyruvate accepts the electrons from NADH to form lactate. What would be the intermediate in this reaction? Would it be NADH or NAD+?
2
votes
2answers
83 views
What exothermic reaction distinguishes warm blooded animals?
I would appreciate an answer specifically in the form of an exothermic chemical reaction. Namely, the one primarily responsible for generating heat in warm blooded animals that does not take place in ...
0
votes
0answers
20 views
What are sulphur contents of diverse biological materials (mostly plants and excrements)?
This is a follow up to my unanswered question: How much sulphur can I assume in protein, in starch, in fat, in feces, in eggs, in meats? Or in specific plants? What ranges? Are there any tables about ...
2
votes
2answers
43 views
What chemicals can be detected from one's sweat?
This question came to mind after reading this article. The article speaks of inducing sweating to determine by a roundabout fashion the amount of salt therein. I'm no medic but I find myself wondering ...
1
vote
1answer
44 views
Formation of ammonia from air and moisture
On extended bicycle trips I sometimes slept under a plastic sheet, which helped with mosquitoes on hot nights. But there was a noticeable build-up of ammonia which made this almost impossible for more ...
0
votes
1answer
42 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 ...
1
vote
2answers
54 views
Does the Urea Cycle exist in invertebrates?
Do invertebrates (like Drosophila and C.elegans) have a urea cycle?
1
vote
0answers
15 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 ...
3
votes
2answers
84 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 ...
6
votes
1answer
76 views
When giving blood, what is the specific Iron measurement they take?
I went to give blood the other day, and they take an "iron" measurement prior to actually drawing the blood. My level was 16.4 -- but what specific type of iron were they measuring?
I've heard of ...
5
votes
1answer
186 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 ...
2
votes
1answer
103 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 ...
4
votes
2answers
199 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 ...
10
votes
2answers
269 views
Could hydrogen replace oxygen in cellular respiration?
I was wondering what oxygen actually does in the body. I have seen a few answers to other questions that involve the electron chain and I am really not sure what that is. So I was wondering what ...
1
vote
1answer
58 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?
3
votes
2answers
217 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 ...
1
vote
0answers
27 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 ...
6
votes
2answers
160 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 ...
3
votes
2answers
36 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 ...
4
votes
1answer
122 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 ...
