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Everything posted by Greippi

  1. 3. Yes, media does have to be sterilised after it's made (usually by autoclave). However, it is best to start with the cleanest water possible (I use normal distilled water rather than the even purer but more expensive MilliQ). Also, it's not just microorganism contaminants you need to worry about. Normal tap water contains all sorts of dissolved stuff (for example fluoride depending on where you live, and various minerals). Distilled/deinonized water removes lots of this as well. 5. The agar setting isn't really a problem (if it does set, it will melt again when it's sterilised by heating, and even if it didn't melt it would still be sterile after heating). The reason it must be autoclaved soon is so that stuff like fungus doesn't grow in the medium - you don't want fungal gloop in there even if it IS killed by subsequent heating. 8. I THINK you're right. I don't know why you would use an innoculating loop at all!
  2. Ribosomes are located within the cytoplasm. Some are free in the cytosol, some are bound to the endoplasmic reticulum.
  3. It does depend on the university you go to. For my undergraduate degree, the geneticists, microbiologists and biochemists all had lectures together. We could then diverge and pick modules based on our interests/core subjects in subsequent years. I think this was quite an important thing to have a broad knowledge and not focus too soon on one subject. Multidisciplinarity is useful these days.
  4. I have many chemistry text books handed down from my father, which will always be useful. I only bought one text book during my undergraduate degree (because they're so expensive and we have a well-stocked library) and I don't intend to let that one go. I kept all my undergrad notes too. My lab is overflowing with text books, it's a nice change from the glare of the computer screen. I'd never get rid of a text book.
  5. The sizes vary, so you're not going to get a precise answer. It depends on specific cases. There are loads and loads of papers on the subject. If you have access to journals then you'll find the information you need. Google Scholar could be a good start.
  6. What is "non-biological data", and how does it thus relate to DNA? Evidently I am missing something here, so I'll leave it to someone else!
  7. Not really sure what you're asking. In response to your second question, probably nucleotide sequence seeing as more than one codon can code for a particular amino acid.
  8. A large proportion of the human genome is composed of non-genomic (by that I mean not translated into protein/peptides) DNA (90% or something). Not all of it is translated. I am sure you'll probably find some nice islands of just A and T somewhere in there. For example, regions of DNA rich in A and T are common in promoter regions. However, the statistical likelihood of finding a several hundred basepair string of A and T is low. Sorry if my response is burbled, I am very tired
  9. What can't you find? Wikipedia/Google searchs identify all the enzymes, cofactors and substrates. S, what specifically are you stuck on? Or are you having problems finding the whole pathway?
  10. What aspect of that do you need help with? It's simple maths.
  11. I only have data for "species", not just animals. Based on records from the past 500 years: birds are becoming extinct at a rate of 26 per million species per year. Factoring species that have become extinct without being recorded, and destruction of habitat: 100 per million per year If you assume these figures applies to all 10 million species on earth: 1,000 species lost per year - 3 per day. Obviously, this is a very rough estimate. Source - a recent issue of New Scientist.
  12. But it will switch to growth phase anyway within 8 weeks won't it?
  13. You have to learn to like the repetitiveness, otherwise there's no point doing research. For example, not every experiment is going to "work" first time round...or second..or third..or...
  14. I was actually going to do a PhD in this field (I accepted another one instead), so Ia would be interested too.
  15. The truth of research is that generally you do sit there doing the same thing over and over again. However, if you're looking to build up your skill set, that's generally not a profitable use of your time. I'm not sure what point you are with your academic career, but you should be careful you don't become "jack of all trades, master of none". You gotta start considering what you ultimately want to end up doing and build up a skill set that will suit that. I'm a biochemist but I spent last semester doing genetics work (which I dislike), because most cell biochemistry projects will require a small amount of genetic manipulation.
  16. I don't understand why merely shaving eyebrows would have any effect on hair growth at all. You're not interfering with the root of the hair, just slicing its top off.
  17. Investigating reaction schemes of enzymes? Lots of work is being done into reaction mechanisms and orders.
  18. Are you putting what should go into the discussion into your results? That's a common error. You write what you find in the results, then explain the findings in the discussion. Discussion can also include ideas for further work.
  19. Yeah, I mean agarose gel DNA electrophoresis. Sometimes when you put an insert into a vector it doesn't work. So you gotta check all the fragments are of the right size on the gel.
  20. Often in the lab, you use restriction enzymes to cut your ligated plasmid to run on a gel, to make sure you have whatever it is you wanted to insert is there. If there's something like that going on, I'd say "aha! an incorrectly ligated vector!" Do you know the size of the cDNA insert? If so, that will give you your biggest clue. Mutation is extremely unlikely.
  21. You need to create a standard curve with the absorbance readings of known concentrations of protein. You can then read the absorbance of your unknown and read off the concentration from your graph. ALTERNATIVELY A280 (1mg ml-1) = (5960nTrp + 1280nTyr + 120nCys) / Mr where nTrp, nTyr and nCys are the numbers of tryptophan, tyrosine and cysteine residues respectively, and Mr is the predicted molecular weight of the protein
  22. I'm not going to answer it for you. What do you use restriction enzymes for? Why would you need to use them? Obviously if you want to use a restriction enzyme, you need to know where the sites are! What is an intron? What is the sequence of nucleotides used for - what does the cell do with this sequence?
  23. I just have a small bit of advice for you: play to your strengths. You wanna hone your skills at what you're good at, rather than completely changing direction. While diversity is good, you don't want to diverge to far from where your strengths lie. For example, if you have a medical degree, you may get bogged down in epidemiological effects (to steal one example from CharonY), if that's your main strength then I don't see the point. I'm a biochemist. If I did a genetics based PhD it would perhaps open up other options for me, but there'd be no point because my talent lies in biochemistry. You are not likely to succeed if you're doing something you're just not interested in. A medical degree is a long time to be bored, and apathy could well set in.
  24. Ahhh I'm sorry, I was ill and a bit delirious. I meant divergent of course! Not convergent. In fact the entirety of my post does not make sense to me now.
  25. You have an absorbance increase - express the concentration as absorbance units.
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