Bioc

Hi, need a little help here. If you are assaying the pressence of a protein during several stages of development of an animal, and you see that, let's say, P1 and P8 have two bands (let's say P0 is the embryonic stage and no protein iband is seen; and the latter stages are P1 to P9) and the rest (P2 to P7 and P9) one band. What is the most probable explanation to this? And how can you verify it? This is what I think: 1)the antibody is recognizing more than one epitope (not very specific) or 2) there is a protein with a very similar epitope (not really think is probable, also relates to 1) in some stages or 3) the protein is an oligomer and it is cleaved in some stages (early and adult). I think 1) is the most probable and I would verify it isolating the lighter protein and re-doing the western blot. If it's positive, then the antibody is not very specific. Any help would be apreciated, hope you can understand me.

Because I recrystallized acetanilide in a water:ethanol mixture (30:1), then filtered it and washed it with 95% ethanol, trying to remove residual water. Thing is, I lost like 70% of solid, so I was (am) kind of in denial, but I think is the only explanation. (btw, It was a test).

Hi, is acetanilide soluble in cold ethanol (~20ºC) ? I found it's about 18g/100ml, but is not a reliable source. I'm asking because maybe I did somenthing stupid...

hum, as far as I know this kind of transformation is to obtain a linear graph, so dy/dx should be the slope. No idea what would happen to the error, tough.

I think wikipedia puts it that way because you are calculating the pH. If you use Kb and [OH-] then you are calculating the pOH. Anyway, pH +pOH = 14, so it must be a convention thing.

Hi, since I infer you precipitated silver with an halide, here is a link where you can get some info: http://employees.oneonta.edu/kotzjc/LAB/SilverGroup.pdf The question is not that hard, don't give up!

Hi, I was wondering why the nitration of acetanilide requires the use of sulfuric acid AND acetic acid. I understand that the acid medium is used to solubilize the acetanilide, so why is concentrated sulfuric acid alone not enough? On a side note, the sulfonitric solution is prepared in another tube and later added to the acetanilide mix. As far as I know, the use of glacial acetic acid is to keep a low percentage of water, and thus, prevent hydrolysis, but this can be achieved using only the concentrated sulfuric acid. So, why is (glacial) acetic acid needed?

Mmmm, a single phase heavy on ethanol makes more sense to me. I saw in a webpage that if you pour cold ethanol slowly, then two phases can form, but that wouldn't explain why would the DNA and the Na+ ions diffuse to the alcohol layer and form the precipitate. I am talking about the simplest form of the experiment btw, the one you can do in your house . None of the websites I have seen mention the use of something to break the wall, so detergent must be enough to atleast cause leakage of the cell material. This is one of the websites I checked: http://learn.genetics.utah.edu/content/labs/extraction/howto/

Hi, I saw this type of experiment on the net, and I don't get a few points. I'm talking about the experiment where you lyse a sample (peas, meat, etc) with a blender, then add detergent and salty water, and finally add alcohol to the mix to precipitate the DNA. What I don't quite get about this experiment is how can alcohol (ethanol) and water form two phases, since ethanol is soluble in water. I think maybe is because the water molecules are solvating the salt and the detergent. Also, in the case of plant cells, I'm not really sure how can detergent break the cell walls. Last, how can salt help precipitate DNA? I know that DNA is negatively charged, it occurs to me that it has a higher affinity to Na+ ions than Cl-.

Can we see it? (with names and other sensible data removed) And trying to answer your question... As far as I know what they test is if the alelles (traits) of specific loci (specific sites of the DNA) are shared among the possible relatives, but people not related can have the same alelle by chance, so this must be backed up with statiscal significance, therefore maybe the matchs you saw are not statistically significant. I don't know why they required the race of some and not yours.

A while ago I saw, in the TV, a woman that was blind, and had some glasses with a cam plugged directly to the brain so, at least in the optics field, some research have been done

In a few words, coupling phosphate bond to substrate molecules makes the substrate more reactive, because as your friend said, phophate bond are high energy bonds (their breakage is exergonic), also the phosphate group is a good leaving group.

Thank you

Well, the water does taste different after you let it "breathe", at least in my opinion.

Thanks for the reply, the context was something like why it is important to use a loading control when you are using a western blot in an experiment using differential protein expression. I assumed it was about using protein expressed with different concentrations or something like that, so looks like I wasn't so wrong.