Jump to content


Senior Members
  • Posts

  • Joined

  • Last visited

Everything posted by Greippi

  1. You can make a guess about whether someone has HIV before it develops into AIDS anyway. AIDS develops when the CD4+ T cell count falls below a certain number. Before you get full-blown AIDS, it is still possible to detect a fall in these cells - very soon after inital infection there is a dramatic fall in numbers. There are also the characteristic symptoms/epidemiology which will give a hint.
  2. Makes sense to me. From what I've seen in my study of the evolution of enzymes different function arises from convergent evolution - the modules are all in place, just to be stuck together like lego blocks to create new things. This could be taken further with the same base set of genetic material that is modified to create new functions - why not deletion of "useless" stuff as well.
  3. My TOP TWO are Voet & Voet and Stryer (both "Biochemistry"), both mentioned in the previous two posts. Personally I prefer Stryer, but V&V was always the most commonly cited during my undergrad degree.
  4. NK cells don't just go around killing anything that lacks self MHC molecules, their activity must be triggered by something. Self cells which lack the inhibitory signals, such as MHC 1 don't have stimulatory stuff, such as antibody bound to the outside of the cell, or some sort of altered self, for example. That's your basic answer, I can go into more detail if you like. The most abundant lymphocytes are CD4+ve - T helper cells. (The most abundant myeloid cells are neutrophils.)
  5. Are they also the same width/direction? I really do think it's to do with lighting - larger space = more light.
  6. ). But there is in the strain you transform the plasmid into (i.e. the plasmid must be put into e.g. E. coli BL21), So T7 polymerase is induced (the plasmid has a T7 promoter). It says that in the manual I linked you (and as CharonY explained).
  7. -Yes, it is used for expression. - Induce with IPTG or infection with lambda CE6 More info
  8. I have never done real-time quantitative PCR but I have studied papers that use it. From what I've seen I'm not impressed, and the results have been inconclusive and the conclusions drawn from them unconvincing. I'll update this with more specifics later when I can find an example.
  9. Considering humans and chimpanzees have different numbers of chromosomes, and children born with an abnormal number of chromosomes are (usually) mentally retarded/suffer various disabilities, I consider this spurious.
  10. The first thing that jumped out at me was this: The DNA purification doesn't look too rigorous. I'm not convinced the arsenic found isn't contamination. If you're going to come to conclusions as groundbreaking as this, the experimental procedure has to be extremely rigorous. But I've discussed it with a number of other people and we've picked so many more holes in the research.
  11. Light intensity has an effect on the gene expression levels of various components of the photosynthetic machinery, too. Maybe it's already been said, or maybe it's obvious - but too high light intensities have a damaging effect - some are perfectly happy to hang around in the gloom under the sea. And, of course, different photosynthetic organisms thrive on different wavelengths of light.
  12. The proof for incorporation of arsenic into nucleotides/proteins etc is not very convincing in this study.
  13. Greippi


    I think your main problem will be that you'll get lots of different fungi (as well as bacteria) growing on that. To do a proper culture you'd probably need a growth medium that is more specific to the ringworm fungus. I can't help you with another suggestion though, I'm afraid.
  14. Gallium causes irritation: to skin, eyes and yer digestive tract if swallowed. Not the wisest idea to eat with it as I expect it would start to melt due to the heat of your mouth.
  15. I think CharonY's hit the nail on the head. I had the exact same thing (although it wasn't just as a result of getting up). It was syncope/orthostatic hypotension episodes due to the fact that I can't control my blood pressure so well (my normal blood pressure is fine, but sometimes it likes to decrease dramatically rather than increase..hah) followed by anxiety/panic. Once I identified the panic aspect of it, and learned to control the panic, things got a LOT easier to cope with.

    1. Zolar V

      Zolar V

      OOOOOOoo are they covalent?

    2. Greippi



    3. Zolar V
  17. An OD of 2.06 is MAD. I'm pretty sure your spectrophotometer will only be accurate below 1. You can't make sensible calculations with 2.06. Dilute your sample 1 in 10 and read again. EDIT: I'm sorry, CharonY pretty much said this. Also didn't notice how old the thread was.
  18. I did this exact experiment for AS level biology 7 years ago. It worked. It worked very well. My thought is that the equipment used wasn't good enough. You have to make sure that you have a good enough seal so that no air can escape AT ALL. I can't remember the exact apparatus we used though - I think it was something smaller than a 50ml beaker (and a muslin bag was involved somewhere), and used more than 5 worms - possibly we used boiling tubes. The experiment was left for quite a while too - at least 3 hours, maybe over night.
  19. Oddly enough, I did this yesterday. But I did it on bacterial cells, maybe it's different for diatoms. I French pressed my cells to lyse them. Then I applied the stuff to the top of a sucrose gradient. Ultracentrifuge over night, then harvested the membrane band. I can give you a more detailed protocol if you like - but the conditions will probably be different for diatoms. It also depends on what you intend to do with the membranes.
  20. Nothing. Unless they have a sperm allergy hah. I doubt a sperm could "dock" on to the animal's egg. And even if it could, fertilisation wouldn't proceed not least due to differing numbers of chromosomes.
  21. Why is it insane that there are two bottles of alcohol? We have at least 11. Use the isopropanol.
  22. It's all in the pathway. There is no point. Obviously there are "checkpoints" and levels of "control" e.g. relying on concentration gradients or whatever. For example: Sensing something = Molecule A binds to receptor A -> receptor A changes conformation and binds molecule B - molecule B binds molecule C - molecule C binds molecule D -> and so on until FOR EXAMPLE molecule X binds DNA and initiates expression of a gene into a certain protein which has a function.
  23. When a receptor receives a signal, it initiates a pathway of molecular interactions and chemical reactions that eventually have an effect. There isn't really a "processing unit" the pathway is already in place, and it just follows whatever pathway until its effect. A cell is essentially a bag of chemicals that work together.
  24. the 0.something is the numerical aperture - from which focal length can be determined (don't know the exact conversions off hand).
  25. Silicon, as opposed to carbon. However, this is unfeasible on our planet as it takes too much energy to make double/triple bonds between silicon atoms - which are pretty much essential for metabolism. Also, it can't make bonds with as diverse a range of atoms as carbon can. There are other reasons too. Chlorine could also hypothetically be used instead of oxygen.
  • Create New...

Important Information

We have placed cookies on your device to help make this website better. You can adjust your cookie settings, otherwise we'll assume you're okay to continue.