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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3answers
43 views

Any good website/book to understand protein folding and enzymes?

I'm looking for a good, understandable and simple explanation about protein folding, mechanisms and function, and their relationship with enzymes. I understand that the protein is a polypeptidic ...
2
votes
0answers
20 views

Membrane potential in gram negative bacteria

Does the membrane potential usually quoted for gram negative bacteria (e.g. E. coli) refer to the potential across both membranes? - If yes, then does the potential fall more over the inner or outer ...
2
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3answers
59 views

Can bioluminescence be used for cancer or tumor detection? [on hold]

What diagnostic applications, if any, are there in using bioluminescence to detect cancer or tumors (in vivo)?
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votes
2answers
2k views

Is it known how the first viruses formed?

The oldest known virus is known to have infected prehistoric insects 300 million years ago. A virus is basically a parasitic strand if DNA or RNA encapsulated in a protein coat. It enters cells by ...
-1
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0answers
30 views

What is the difference between caspase and DNase? [closed]

Could somebody tell me what the difference between caspase and DNase is?
1
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1answer
56 views

Amino acid compatibility

The (human) genetic code encodes 20 amino acids. They form a protein using peptide bonds. Each amino acid has a carboxyl group (COOH) and an amino group (NH2) that can potentially form a peptide bond. ...
2
votes
1answer
14 views

Does mung bean nuclease cleave a phosphate group when it's chewing off 5' or 3' ssDNA ends?

I'm looking to create blunt ends from sticky ends with mung bean nuclease for subsequent ligation. Does anyone know full mechanism by which mung bean nuclease will do this? In particular after the ...
2
votes
1answer
20 views

Edman method to identify peptides with Phenylisothiocyanate (PTH)

We all know that in this method the PTH reacts with the first amino acid (aa) from the N-terminal to the peptide and separates from it giving PTH-aa so that we can know the amino acids sequence in the ...
3
votes
1answer
49 views

Proteins in Milk, Oat , Eggs and Soy

I have read that there are proteins in oat which are similar to those in soy, milk and eggs. I know nothing about biochemistry, and I'm struggling to decipher the info i find.. the closest Ive got to ...
1
vote
1answer
20 views

Hydrogen peroxide decomposition and catalase uses [closed]

All google searches have simply returned more info on catalase. I'm looking for a catalyst that isn't found inside living organisms which can break down H2O2. Looking for any resources to look at, or ...
9
votes
2answers
218 views

What is the explanation for the smaller number of tRNA than codons?

Translation, or decoding, of the four-nucleotide language of DNA and mRNA into the 20–amino acid language of proteins requires tRNAs and enzymes called aminoacyl-tRNA synthetases. To ...
4
votes
1answer
191 views

Why is E.coli used as a model?

Is there a reason for the choice of E.coli as a model for many bacterial systems? Other bacteria such as B.subtilis are also used, but why is E. coli preferred?
6
votes
3answers
44 views

Mechanism by which $lacI^{d}$ is a dominant mutation, impairing the function of normal copies of the Lac Repressor

Jacob-Monod model for the lac Operon was based on experiments using two strands of bacteria which constitutively expressed $\beta$-gal: $I^{c}$(mutation in the gene lacI , which encodes the repressor) ...
1
vote
0answers
18 views

Why do contrasts during CT scans make the body feel warm? [closed]

Why do the contrasts used during CT scans make the body feel hot/warm? I think they use iodine, so why would the bodies response to iodine be a warm sensation? In addition, I think they make one's ...
1
vote
0answers
22 views

Is it possible to isolate and analyse intermediates of protein folding?

I would like to know if there is an assay which could allow us to analyse a protein before it has assumed its 3D functional form. While studying structural biology, I only came to know the forces that ...
3
votes
1answer
35 views

Divalent cation binding to calmodulin

I have carried out a native PAGE with 4 reaction mixtures. To each I had added an equal volume of EDTA (1 µl/1mM) to sequester any divalent ions and an equal volume of calmodulin (5 µl/0.5 mg/ml). I ...
4
votes
1answer
40 views

Cellular Respiration/Fermentation Problem Leading to Lack of Energy

A young animal has never had much energy. He is brought to a veterinarian for help and is sent to the animal hospital for some tests. There they discover his mitochondria can use only fatty acids and ...
4
votes
1answer
21 views

What's the maximum pressure inside a bombardier beetle?

This question got me wondering about the pressure inside a bombardier beetle. Lots of articles mention pressure, but don't specify the amount of it: One study records the velocity of the spray to ...
4
votes
1answer
265 views

What is our skin made up of?

Again, it is a basic question. What is our skin made up of? is it made up of many cells arranged in a systematic way or is it just like any layer say of a book?? what is the difference? where is the ...
0
votes
0answers
31 views

What is the probe that absorbs at 450nm in the presence of NADH in this assay?

The colorimetric assays by Biovision and Sigma Aldrich seem to utilise a probe that binds to or reacts with NADH in order to cause absorbance at 450nm which can then be quantified by a ...
1
vote
1answer
53 views

Why sigmoid curves appear in quantitative analysis of many biological phenomena? [closed]

I know two examples: 1-The binding of hemoglobin to oxygen (binding of oxygen to one site of hemoglobin induces conformational changes which increase the affinity of the other sites for oxygen - the ...
3
votes
2answers
35 views

Biochemical coupling between two enzymatic reactions - Enzymes physically associated?

I am wondering what the exact definition of biochemical coupling between two enzymatic reactions is. I know that these two enzymatic reactions have to share the same intermediate(s) one is ...
4
votes
1answer
33 views

To which negatively charged components of the cell envelopes do the crystal violet complexes bind in gram staining?

The gram positive have negative components in the peptidoglycan layer in the form of teichoic acid phosphodiester bonds, and the gram negative have negative components in their outer membrane in the ...
5
votes
1answer
86 views

Why does high pH result in the denaturation of DNA?

In the Southern blot method, for example, a solution of NaOH is used to denature the DNA in the sample. I find this counterintuitive since I expected that $\text{Na}^+$ cations would neutralize the ...
0
votes
1answer
39 views

Examples of how the presence or absence 2'-hydroxyl groups influence physicochemical properties of DNA and RNA

I know, for instance, that RNA is much more succetible to alkaline hydrolysis than DNA and this difference is determined by the presence of 2'-hydroxyl group in ribose. I have also heard that "DNA is ...
0
votes
0answers
13 views

Does the use of a Thiazide diuretic affect the ability of a hair follicle to absorb substances?

Thiazide diuretics are on the World Anti Doping Agency's, as well as the International Olympic Committee, list of banned substances due to it ability to mask illegal substances in urine. The rapid ...
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vote
0answers
35 views

If you are God, how would you create an efficient priming reaction? [closed]

Imagine that you are “natural selection” (or God if you prefer) and you can reconstitute replication changing the concentrations or the properties (higher/lower activity; reactivity; etc.) of the ...
1
vote
3answers
86 views

Does the necessary Carbon Dioxide need to be in the atmosphere for mammals?

In the answers to this question, we've learnt that carbon dioxide is necessary for mammalian life, but is it necessary in the atmosphere/to breathe it in? Or does the act of respiration give a ...
4
votes
0answers
46 views

What is the difference between organelle membranes?

Cells and organelles are contained in lipid bilayers. I'm particularly interested in eukaryotic organelle bilayers and the biophysicochemical differences between them. Many papers assume a ...
1
vote
2answers
32 views

Determination of a chemical compound in a non-homogeneous sample

This is a more generalized question of my other question here. I want to know if it is possible to determine a chemical compound in a non-homogeneous sample. I am asking this because we are aiming ...
4
votes
2answers
42 views

what does Pro→Glu substitution mean?

Considering the paper: A single amino acid in E-cadherin responsible for host specificity towards the human pathogen Listeria monocytogenes in the abstract portion, what does Pro→Glu mean? Does it ...
6
votes
4answers
61 views

Enzymatic error rate

I am aware that each enzyme generate a certain amount of misproducts. This is well documented, for example, for the DNA polymerase. I am interested in enzyme involved in biochemical processes, so for ...
6
votes
1answer
61 views

Which will produce more oxygen? Less number of (larger) trees or more number of (smaller) plants?

In a given area A, we have two choices - (i) we can plant maximum number of trees (which are larger in size) possible in A, say m OR (ii) we can plant maximum number of plants (which are smaller in ...
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0answers
32 views

Which method would more accurately help to identify the unknown concentration of a protein sample between the A280 and the Bradford methods?

I quantified my protein using the standard Bradford method and the A280 methods and obtained values that were far off from the theoretical value of the protein of interest, and therefore was wondering ...
14
votes
1answer
943 views

What is the most condensed form of (stored) energy used in biology?

When considering how organisms store energy for later use, I was wondering what substance known in Biology is best for compacting the most energy in the smallest space(volume-wise). With my (limited) ...
1
vote
0answers
36 views

Zinc and brewer's yeast

I'm hoping for some information relating to yeast nutrition (specifically Saccharomyces cerevisea) in beer fermentation. Zinc is well-known to be necessary for yeast cultures to perform successful ...
1
vote
0answers
54 views

How does estrogen influence collagen synthesis?

Through what mechanisms does estrogen interact with collagen synthesis? Especially in the context of elevated estrogen levels and genesis of purpura simplex .
4
votes
2answers
70 views

What is a triglyceride?

I'm confused on what a triglyceride is, from what my text book it says its a type of gylercide, then from a website it said Glycerides can be subdivided into two categories. The first group, the ...
0
votes
0answers
30 views

Is there a biological environment that we can we assume glutamate exists as glutamic acid?

In the body we almost always assume that glutamate exists as glutamate rather than glutamic acid. It is so commonly glutamate yet glutamic acid and glutamate share the abbreviations of Glu and E. From ...
2
votes
2answers
43 views

How to preserve leaves between sampling (collection) and analysis?

Suppose I spend a day in a forest, collecting different kinds of leaves, which I would like to analyze under a compound microscope. Now, obviously, measures should be taken to preserve the leaves some ...
5
votes
1answer
52 views

Is using Hidden Markov Models to find homologues sensible in abstract, short sequences?

HMM alignment tools like hhpred excel at finding subtle homologues of folded proteins that simpler scoring techniques (such those used in BLAST algorithms) would miss. I am only looking at a small ...
2
votes
1answer
33 views

Why is the resting potential of a neuron so close to the equilibrium potential of K⁺?

I know this has something to do with the K+ leak channel. I just don't understand how. I know that 3 Na+ are pumped out for every 2 K+ pumped in. This makes the cell interior net negative. I know ...
1
vote
1answer
34 views

Are there U-rich transcriptional pause sites?

I've heard a statement in a talk that U-rich sequences cause transcriptional pausing. The intuitive explanation for this was that the UTP concentration is lower in the cell than the ATP concentration. ...
0
votes
0answers
23 views

Explanation of sequence motif diagram given in wikipedia [duplicate]

can someone please explain me this graph?? I did not get what information content is in this graph means. Does the size of the letter indicate that higher chance of that letter to be present in that ...
3
votes
0answers
24 views

How does beta branching stop alpha helices from forming?

I am told that beta branching interferes with alpha helix formation. Problem is that I don't see how beta branching has anything to do with alpha-helix formation. Beta-branches are on the outside of ...
0
votes
0answers
20 views

Cannot conjugate Biotin-labeled DNA to Streptavidin-labeled solid surface

I have been trying to immobilize DNA by the bioconjugation of biotin and streptavidin, but I cannot get this work. I added EDC and streptavidin to COOH ...
1
vote
0answers
15 views

Which biosynthetic pathways take place in the plastid and were are they located?

I know that the isoprenoid, jasmonate, glucosinolate, fatty acids, chlorophyll, starch, and aromatic amino acid syntheses are located in the plastid. But I don't know if they are located in the ...
1
vote
1answer
26 views

Dehydration from caffeine, alcohol and other

Tea, Coffee, Beer, Coke etc… I wonder if the benefit from amount of fluid we get from them is bigger or smaller then the handicap of dehydration. In other words it is worth to drink them if we want ...
2
votes
1answer
52 views

Dehydration by a tea, coffee, beer etc

For the long time I am trying to find out if the following is truth: They say that some beverages dehydrates. I heard that about tea (sometimes green, sometimes black, sometimes both), coffee, beer ...
1
vote
2answers
42 views

Conversion of glucose to glycogen

Why is excess glucose, as a glycogen, stored in only a limited amount as compared to the lipid in our body? Why is mature glycogen arranged (polymerized) in 12 tiers polymer?