Biochemistry and Molecular Biology

You have prepared a 0.2 M histidine solution. Calculatethe molar concentration ofisoelectric histidine at a) pH 5.5 B) pH 7.0. An "isoelectric aminoacid" is the structurein which the molecule has no net charge. Calculate the pHof a solution obtained by adding 20 ml of 0.20 M KOH to 480 ml of 0.02M isoelectric glycine.

What are the major groups of bacteria?

what is the most heat resistant microorganism and how high a temperature would be required to kill it

I have a confusion with terminology, which should be easy to resolve I guess.. What does term "fractional saturation" mean in the case when a receptor has more then 1 binding site? (let them be equivalent and independent). By definition, it is the "fraction of the protein molecules that are saturated with ligand", so in case of one site it is just Y=[PL]/([P]+[PL]). But when it comes to more binding sites, I am confused. Lets say there are 2 binding sites. Then, fractional saturation is either, following the definition, [PLL]/([P]+[PL]+[PLL]), or something like ([PL]+2[PLL])/2([P]+[PL]+[PLL]), meaning that it is a fraction of binding sites, saturated by …

Photosynthesis, the process by which plants get their energy from sun light. What part(s) of sun light(ex: visible infrared uv... ) do they actually get energy from? How is this done?

Hi there, I would like to carry out an enzyme activity assay for the galactosyltransferase enzyme in the Golgi of CHO cells. I found a paper with a protocol using tritium labelled UDP-Glucose as donor substrate. I've tried to contact the authors for more details but have gotten no reply. As its my first time working with radioactivity I would like to know if my dilution calculations of radiolabeled glucose are ok or are totally incorrect? Your advice is greatly appreciated. The protocol suggests using 0.5 mM Glucose at 50,000 dpm / nm in a 25 ul assay. I take it the dilution must first by made up for the radiolabeled glucose with non-labeled glucose be…

So I think I've hit a roadblock. I see that in a lot of biochem enzymatic reactions, two substances are held in equilibrium (for example in glycolysis, DHAP and GAP are in equilibrium through an enzymatic reaction). However, I've also read that an enzyme will convert a substrate into a product and that the process is irreversible (E + S <---> ES ---> EP <---> E + P, where the middle step is irreversible). So my question is how can both be true? How can a substrate and product be converted back and forth by an enzyme (to establish equilibrium) while at the same time the form of an enzymatic reaction is irreversible?

I am currently busy with enzyme assays (well, trying to be): This is what I am doing, but its not working... I induce mouse hepatoma cells with ethanol and a test compound. The test compound is supposed to cause the transcription of my enzyme which I am supposed to measure the levels of after cell lysis, freezing and thawing. However, after measuring the OD, there seems to be NO significant difference between ethanol and test compound induction, i.e. I generated two identical looking curves. This is so frustrating.

just something to exercise your creative minds. This is in no way meant to be serious, just a general musing. hence its location in this forum. Having seen Resident Evil recently I started to think about the most efficient and successful way of killing people. The method used was the spread of the virus material itself first through an airborne carrier. inhallation results in the deceased becoming zombies, infecting whoevere they bit etc etc im sure you know the plot. the question im asking is, given the aim of eliminating as many people as possible, what do you think would be the best method through which to do this? nerve gas seems basic seeing as it only kills …

Hi Guys! I'm having some troubles with this exercise! Glutamate is marked in C1 and N with a radioisotope. I have to guess which atoms of the following molecules would me marked: Urea ( to me it should be N1) Succinate (C4? I've considered it as entering the TCA cycle) Arginine (N1?) Citrulline( N1?) Ornitine ???? Aspartate (C1??) Can anyone tell me if I'm right? I've thought Glutamate's as being a part of CarbamateP making all the urea cycle , while I've supposed that the C backbone become aKg. Anyway I fear there's something wrong! Help meee

Hi, I was wondering how come neurospheres (generated by neural stem cells) don't adhere to the bottom of the petri dish? I thought all of the cells when they weren't clung to the petri dish meant the cells were dead...why isn't the case with stem cells? Thanks in advance to all those of you who can answer !

is Na and glucose cotransport is the only transport to transport glucose into blood in small intestine

Hello everyone, I've recently been admitted to a degree in biochemestry.This is my second BA - the first has been a humanistic one.Needles to say that I've grown away from the "hard science" needed in this field.My question to you is : what should I study before the begining of the year to get up to speed? thank you

As you (should) know, little kids grow in stature because our bodies are constantly creating new cells. As a child, our body creates cells faster than old cells die, which cause us to become physically larger. At age 18, the rate at which cells are created start to cancel out with the rate at which cells die, causing us to stop growing. However, in our elderly years, our cells start to die faster than our body can manufacture new ones, causing us to, essentially, shrink. Does that mean that, at least in theory, if we could avoid all other forms of death, and live long enough, we could eventually shrink to the size of a fetus or zygote, and die THAT way?

why essential aminoacids eventhough essential for the survival is not synthesized in the body?

I assume cofactors & allosteric control are closely related. Are all cofactors a method of allosteric control? And is all allosteric control based on cofactors? Thank you greatly.

What is spontaneous generation?

I am trying to amplify a portion of DNA from a genome (and get no band), I also included a positive control while I was doing a temperature gradient from 37c to 55c. For the (+)control, I got one band (with its size fit) at 55c but none at 37c. If I got no band with a higher temperature I can deduce it is due to the inability of primer to bind onto genome template, but now it is the lower temperature which showed no band. With a lower temperature, multiple bands due to multi-target makes sense, but I do not know how such a band pattern is result. Hope get any help, thanks.

So I was looking up and cross-referencing articles on ground substance for an article that I am labouring over. I have never submitted an article before...trying to thoroughly do my research...but I stumbled across this amazing article via wiki, and really it made me fall in love with the cell all over again. I saw it presented in a way that I had not thought of before, so I wanted to hear the snf's community's thoughts. http://jeb.biologists.org/cgi/content/full/206/12/1955

Question: Does anyone know if you can generate a cell line knockout in any cell line or does it have to be an embryonic stem cell? If so why? I'm thinking about doing a series of experiments in HEK 293 cells and would love to KO my gene of interest to determine the effects on cell viability and was wondering if I can do that by homologous recombination. Any thoughts/ answers would be greatly appreciated.

Hello forum! First time posting here but I intend to stick around. I'm wondering (and hoping) if anyone could provide some insight on expressing and secreting two independant proteins in E coli. I've scoured the literature and have found plenty on dual expression (see this article), but nothing that includes secretion too. The idea so far would be to use either a pre-made expression vector like Novagen's Duet and then adding signal sequences in the ORFs to secrete the proteins. Alternatively, I could design my own dual expression vector to do the same thing. I'm hoping to have this ready by September, although I realise it's pretty ambitous considering there's…

Does anyone know the sensitivity range of nested pcr ? I tried goggling but could not get the answer . I am from INDIA . Is nested PCR sensitive enough to detect the acute infection Hepatitis c infection between 4-6 weeks ? I did the two pcr and got condractory relsults. This answer will help me a lot because , I had HCV PCR done realtime PCR got results as "HCV RNA DETECTED" on fourth week after exposure . And the lab which i did the first was not a very famous one. As many said that my risk factor was very very unlikely to cause infection . After a week of first pcr , I did NESTED PCR RNA in the most reputed lab In my state which has got Col…

hey guys, i got a fusion protein of a KR (25,5 kDa) and a FDH (44 kDa) linked by a polyglycine linker. in sds-page, there is not only the fusion-protein but also a strong band of the 44kDa protein. do you have any ideas why that could be? maybe the linker degrades? but i didn´t find any proteases or stuff that cut polyglycine... or is the template to long and polymerase falls off? but why is it always the 44kDa band that is seen clearly? oh one more thing: i added a his-tag to the fusion protein and the recovery (estimated by sds-page) was only about the half! there was no overexpression at all...now how the hell could that happen? you see, i have no idea=) …

Can somebody please explain to me the difference between semi quantitative and quantitative PCR ?

Synthetic peptides could be used for the following purposes: • To verify the structure of naturally occurring peptides • To study the relationship between structure and activity of biologically active proteins and peptides and establish their molecular mechanisms and • To develop new peptide-based immunogens, antibodies, hormones, vaccines, etc. Synthetic peptides may range from 2 to 120 amino acids. Small synthetic peptides (in general less than 10 amino acids in length) have the advantage of rarely inducing antibody formation and can be tailored to move across blood brain barrier. Peptides for antibody production are generally of 15 to 25 amino acids. Such peptid…