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

learn more… | top users | synonyms

5
votes
0answers
108 views

SDS Laemmli Gel that did not solidify [closed]

In my lab class this week my partner and I were making a SDS-PAGE Laemmli Gel. We made the resolving gel solution which was made of 30% Acrylamide, DI water, 1.5 M Tris-HCL pH8.8, and 20% SDS. We ...
2
votes
1answer
737 views

Green Film Build up in Glass Water Bottle

So I have this Large Water Jug that I fill only water with. And this is the 2nd time there has been a layer of green film that builds up at the bottom of the bottle. I don't have any way of getting ...
1
vote
1answer
3k views

How is ATP involved in muscle contraction?

The sliding filament mechanism as explained by my text does not elaborate on how ATP is involved in the cross bridge binding and contraction process. How does muscle contraction utilize ATP? In my ...
1
vote
3answers
83 views

DIY storing family DNAs' samples for future uses (eg medical)

I have a question I could not get an understandable reply from Google and I am no expert in the matter, so my plead to you is if you could give me practical and relatively easy to follow advice. With ...
1
vote
1answer
125 views

Given an EC50 value, how do I reproduce the sigmoidal curve from which this was calculated?

All-trans retinoic acid (atRA) is a potent ligand for a nuclear receptor called retinoic acid receptor alpha (RARa). The concentration of atRA at which RARa is half maximal is 19nM. The dose-response ...
1
vote
1answer
50 views

ratio between heat transfer coefficient and thermal conductivity [closed]

Consider the Robin boundary condition for the diffusion/heat equation $\mathrm{u_t=a(t)u_{xx}+f(x,t)}$: $$\mathrm{-k(t)u_x(0,t)=h(t)u(0,t)}$$ or $$\mathrm{u_x(0,t)+\frac{h(t)}{k(t)}u(0,t)=0}$$ ...
6
votes
1answer
45 views

What Goes on in Photosystems at the Molecular/Atomic Level?

In light-harvesting complexes, how is the energy of a photon transferred from one pigment molecule to another? And in reaction-center complexes, how does the primary electron acceptor capture an ...
2
votes
1answer
277 views

How to define drug-resistant or -sensitive cell line when knowing the IC50 values?

I have got the IC50 data for a drug on different cell lines. How to define if the cell line is sensitive or resistant towards this drug? Could anyone tell me how to define this?
0
votes
1answer
31 views

Beta oxidation of saturated fats

In my text book there is an example of a 18 carbon long fat and it says that it can run 8 laps of oxidation. I don't understand why it doesn't run 9? 2 are removed each cycle? Thanks.
0
votes
0answers
53 views

Why doesn't the body optimize how many fatty acids it burns?

Ketone bodies are produced due to an excess of fatty acids being burned (accumulation of acetyl-CoA) so my question is: Why doesn't the body simply regulate how many fats it burns so it doesn't have ...
2
votes
1answer
60 views

How are ketone bodies used?

While searching for literature on ketone bodies, I can only seem to find how they are synthesized, but not how they are broken down. I'm looking for the series of events with enzyme names and ...
10
votes
3answers
970 views

What is the purpose of gluconeogenesis?

The gluconeogenesis pathway seems quite pointless to me. I don't understand why an organism would want to spend energy to create a molecule that can then be metabolized again for less energy? The ...
4
votes
1answer
65 views

NADH shuttles - Why cytosol?

Why is the malate-aspartate and the glycerol-3-phosphate shuttles located in the cytosol and intermembrane space? The krebs cycle happens in the matrix so why wouldn't they push electrons from the ...
4
votes
0answers
43 views

Cholesterol's role in lipid uptake [closed]

I'm studying the digestion of fats and I understand that our dietary fats mostly consist of triglycerides. We absorb the fats and eventually they end up in a muscle/adipose cell for storage (as ...
5
votes
1answer
1k views

Where do amino acids get attached to tRNA and where is it synthesized?

Some very basic parts of transcription/translation seem to be left out in various literature. I can't find the answer to this anywhere: How exactly is tRNA synthesized? I realize that mRNA is ...
4
votes
1answer
556 views

Water soluble molecules

I believe I may have misunderstood water solubility this entire time. I assumed that water soluble meant that it would literally dissolve in water. It would break down into atoms. A sugar molecule ...
5
votes
1answer
204 views

Why does a “cascade” of events happen during signal transduction?

I've been watching some videos on signal transduction and it says that because there are enzymes being activated by the signal, then there is a "cascade" which happens afterwards...I don't understand ...
2
votes
2answers
93 views

What are the typical values of probabilities for nonspecific binding to an antibody?

I'm physicist by training, so please excuse me if I don't use the proper terminology. I think there is a way to make a sensor that detects if a single antibody has caught something from the flow. So ...
1
vote
1answer
292 views

Pasteurization and Bioavailability of Antioxidants in Beet Juice

What are the effects of pasteurization on the antioxidants found in beet juice ? Does the process render most of the beneficial nutrients (betaine) useless and make them unable for the body to process ...
1
vote
1answer
26 views

Ways to cause membrane damage to microalgae and yeast?

I am researching a way to monitor the membrane damage of cells. To do that I fist have to have reference points, namely, cells with damaged membranes. I am working with Dunalliela, Hematococcus (both ...
3
votes
2answers
88 views

RNA polymerase question

In this question we are examining a bacterial RNA polymerase that elongates at 20 codons per second. Question 1: How long will this RNA polymerase take to transcribe the Lac Z gene at 3510 base pairs? ...
5
votes
4answers
468 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 ...
4
votes
2answers
181 views

Are Gram negative bacteria classified as such because of their negative membrane potential?

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 ...
3
votes
3answers
145 views

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

What diagnostic applications, if any, are there in using bioluminescence to detect cancer or tumors (in vivo)?
18
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 ...
4
votes
3answers
302 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
75 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
109 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
110 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
218 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 ...
13
votes
2answers
3k 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 ...
5
votes
1answer
253 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?
7
votes
3answers
175 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
36 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 ...
5
votes
1answer
65 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
145 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
1k 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
30 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 ...
5
votes
1answer
2k 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
107 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
318 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
115 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 ...
5
votes
1answer
395 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 ...
1
vote
1answer
58 views

Which organisms have their cell wall made of polysaccharides and amino acids?

I came across a question which somewhat goes like In which of the following kingdom, most of the members have a cell wall made of polysaccharide and amino acids ? - Monera or Fungi. To me it ...
5
votes
1answer
6k 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 ...
1
vote
1answer
218 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 ...
1
vote
0answers
23 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 ...
1
vote
0answers
44 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
201 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 ...
8
votes
1answer
509 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 ...