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dttom

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Everything posted by dttom

  1. But if the dye binds protein proportionally, says, 1 dye to 1 protein; and says 20mg of BSA contains X mol of BSA; 20mg of my sample might contain Y mol of protein; so X mol dye bind to 20mg BSA, and Y mol of dye bind to my sample (20mg); though their weights are the same, but the color intensity (due to amount of bound dye) will be different. How could this be bypassed?
  2. a) that mean those which are not double recessive, and you got the allele frequency for d, you should be able to calculate that. b and c should be figured out once you got a). d) so you need to know the genotype of the parents.
  3. do you have markers, comparing your band with the marker should tell the length of DNA.
  4. It has been a routine practice to estimate a protein's amount by preparation of a standard calibration curve by BSA and with a spectrophotometer, followed by comparison with absorption of the sample protein. But I have been confused if this technique is to determine the concentration of protein (in molar) or the amount of protein (in milligram per litre). I have heard of both approaches. When I check how the component Coomassie blue in Bradford reagent work, it is found that this dye binds to protein molecules proportionally (not dependent on protien length), so I would then think using this technique to deduce protein concentration would be a suitable one, but I couldn't understand why people use the same technique with weight determination (or weight determination only effective when calibration protein got a similar molecular weight with sample protein?). Hope for any help. Thanks.
  5. There should be different proteomes in different cell types, and it is these proteins sensing environment through signal transduction and also which intrinsically determine the potential for regeneration.
  6. I think this could only be done with suitable enzyme, some plastics could be degraded by bacteria like polylactate, but what about metal? degrading metal, is it equivalent to oxidising it so that it dissolves as ions? think so.
  7. Sorry I could only barely grasp what you mean, could you see if I summarise it right? "If the PAGE plate is pretreated with thiosulfate, upon formalin addition, thiosulfate and formalin form an equilibrium, to a degree preventing excess reaction between formalin and silver nitrate; however, in regions of protein spot, the protein would screen the thiosulfate nearby (thiosulfate content would be lower in those spots), together with proteins as a more suitable nucleating site, silver (metallic) would be mainly deposited on protein spots."
  8. Yes, that is silver staining for protein on gels (PAGE). Silver is used to reduce background staining? Could you elaborate a little bit about this, I assume the silver ion (in silver nitrate) acts as an oxidising agent...
  9. In silver staining, thiosulfate is used to sensitise the electrophoresis plate, for easier subsequent staining, but could anyone tell why and how thiosulfate can do this? The protocol used is like this: silver nitrate staining: 1) sensitised by thiosulfate; 2) immerse with silver nitrate; 3) apply mixture of formalin and potassium carbonate (carbonate what use? remove proton formed from oxidation of formalin?); ammoniacal silver staining: 1) sensitised by thiosulfate or plate prepared with thiosulfate; 2) immerse with ammoniacal silver nitrate; 3) apply mixture of formalin and citric acid; So, silver nitrate method and ammoniacal silver method differs; on application of formalin, in the latter case, ammonia seems to be pulled out from silver complex by adding citric acid, so I wonder if the property differences come from the process of application of silver solution, instead of in the process of reacting formalin. Would someone mind clarify this? Thanks.
  10. Square root is troublesome, now if you don't want root what would you do?
  11. Earth is not a sphere and is rotating so g is different for different location. But I doubt if latitude could be found.
  12. Imagine there is a vesicle holding 100 sucrose, one disaccharase comes in, and break sucrose up to glucose and fructose, vesicle membrane can't withstand the osmotic pressure and burst, that disaccharase bursts out and moves to another sucrose vesicle... What if you consider that disaccharase as an enzyme catalysing production of itself? What if the product are not glucose and fructose but disaccharase itself?
  13. Electroosmosis is the movement of bulk fluid under the application of a voltage across. This seems to be also essential for electrophoresis, obviously, no emf, no electrophoresis. But I was told that electroosmosis could be a hindrance to movement in electrophoresis. My teacher said that, the factor of electroosmosis only comes in when a charged supporting medium (the substratum) is used, molecules to be separated converged to the medium, their covergence bring with water (to balance the osmotic potential), when the voltage is turned on, all the water blast towards to electrodes leaving those molecule stationary. In this explanation I understand to the point where molecules accumulate onto the medium and draw in water, but I can't see why when the switch turns on, water will rush towards electrodes. Could anybody help or give other explanation how electroosmosis hinders electrophoretic movement? I have thought of a simple explanation, that is the charged medium holds and retard the molecules hence it is one of the resistive forces. Another explanation I could understand is that the molecules are trapped inside pores of the medium, and if the medium is charged it will have its boundary coated with a layer of ions (from the bulk liquid/electrolyte), this layer of ions will shield the emf applied , force pulling molecules force will then be weakened. Comments on my own intepretation are welcome. Thanks.
  14. I have heard of two such reagent, one is sulfuric acid, another one is iodine, both of them are claimed to have been able to stain all carbohydrates, amino acids, and fat. But I'm interested in the mechanism, or chemical reactions involved. For the sulfuric acid as a reagent, possibly, though I'm not quite sure, is due to dehydration of targets resulting in carbon formation making the spots visible. For the iodine, I know iodine could stain starch by complexing, but I can't think of a staining mechanism for other carbohydrates. For fat, maybe the iodine vapor dissolves into fat and such dissolved iodine appears purple. The amino acids again I have no idea how it works. By the way I'm also not sure if there is no particular chemical reaction involved, may it just because of higher affinity of iodine to those organic substance? But even if it is, why iodine would have a greater affinity for its targets?
  15. I can understand it is a gradual process so when one increases another decreases, but what I doubt of is the timing, I think the quality which follows another quality should show some lagging behavior but not in simultaneous manner...
  16. The definition I got it from my professor, but when I re-check it you are true that the effect is on fermentation, but as you said the energy-generating process is glycolysis so other description would be the same. Again ATP deprived from TCA and oxidative phosphorylation is not available in the absence of O2, hence ATP level drops, negative effect on phosphofructose kinase 1 relieved and NADH level rises (an indicator of glycolysis); but still I think there should be a delay. (what I think does not fit the graph explanation which is suggested by the professor) About how the graph is actually look like, I've drawn a graph here, but the actual one is not as perfect as this one, with random irregularity, but the exactly out-of-phase relationship could still be observed:
  17. Fossil record is not the only evidence supporting evolution, with it incompletely (actually if the fossil record is a complete one you should be surprising if you consider that many geo-activities); modern molecular evidence also supports evolution and a lot of fact could be explained following theory of evolution. Micro- and macro- evolution have never a clear boundary, if we see a large change between two samples we call it a macro- step, but who to define what 'large' is meaning? But it should be fair to say microevolution is required for macroevolution, not excluding the latter as an emergent subject. There are evidence supporting punctuated evolution, in which series of 'quick' evolution are separated by a rather long gap when little or no evolution occurs; if you consider the 'quick evo' as a moment, you may define a species, then why two species should show intermediates?
  18. You need to check out the corresponding thermodynamic data, chemcial potential difference in the process you mentioned might be similar but there might be differnece in terms of entropy.
  19. Pasteur effect states that the presence of oxygen would suppress the glycolytic rate. Modern interpretation is that oxygen allows procession of Krebs cycle and electron transport chain, generating an amount of ATP far exceeding that from glycolysis alone. ATP in turns suppresses a rate-controlling enzyme in glycolysis of phosphofructose kinase 1 allosterically. I was given a graph showing periodic relationship between ATP and NADH, which is a product of glycolysis and serves as an indicator of the procession of glycolysis. The graph shows an exactly out-of-phase relationship. However, I think that, according to the mechanism suggested, the kinase has to be given a period of time to 'feel' the suppressing effect of ATP, so the NADH curve should be slightly differing from out-of phase relationship by lagging a little bit. Could anyone comment on this?
  20. dttom

    Gold

    if that's impurities inside undergo some chemical changes, it should not be returned to their original state spontaneously.
  21. ln(A0/A) = kt substitute all the number you get the answer.
  22. dttom

    A plasmid problem

    The plasmid don't have a MCS but you reminded me to look at the detail structures of it and the problem has been solved now, thank you.
  23. I met a problem in manipulating plasmid in my project, here it goes. I have a plasmid with an insert, which is capped between two identical promoters in different directions, so a dsRNAs could be produced. Now if I want to chop the insert into pieces, then just incorporate one piece (a random piece) of them in bewteen the pair of 'caps', what should I do? Any comment would be appreciated, thanks.
  24. Let x be the effective concentration of the ion providing the electrode potential; y be the effective concentration of interfering ion; and xnx + ne- --> x The resulted emf after ion interference is given by: E = E0 + (RT/nF)(ln(x+y)) So then how could the equation be explained qualitatively?
  25. Usually you should make it flling your paper, and you are just required to indicate the microscope magnification used.
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