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PopGen

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Everything posted by PopGen

  1. MWHAHAHAHAHA! You have all made the same mistake! The probability that individual 14 is heterozygous is actually 2/3. Since we know that this individual is not homozygous recessive, she must be either homozygous dominant or heterozygous. It is twice as likely that she will be heterozygous rather than homozygous dominant, hence there is a 2/3 chance she will be heterozygous.
  2. No offence, but where do people get the impression that animals are defined based on physiology instead of evolutionary relationships? The definition of animal is simply that you are descended from the same common ancestor as all other animals. If, since that branching point, you have managed to pick up the ability to photosynthesis, you don't magically stop being an animal.
  3. If symbiosis doesn't count as doing photosynthesis, then plants can't photosynthesis either, since all the photosynthesis in plants is done by a symbiotic cyano-bacteria which lives in their leaves w/ a leaky cell wall. The definition of animals, btw, depends on descent and not current ecological niche. Just like there are some plants that don't do photosynthesis, there are some animals that do (though the symbiosis in the case of animals is still relatively new and fragile).
  4. The end goal of GMing an organisms is getting new DNA into the organisms germ-line cells (i.e. sperm/eggs/pollen etc.). For some organisms this is absurdly easy, and simply involves growing the organisms in the presence of the DNA. Most organisms, however, are much more protective of their cells and resist assimilation of environmental DNA (either by degrading the DNA or triggering cell death in cells which assimilate the DNA). Two main techniques exist for getting foreign DNA into plant cells. The most general technique is to simply shot the DNA into cells attached to tiny inert particles. Once inside the cell the DNA can sometimes stably integrate into the plants genome as a plasmid. I'm not sure about plants, but in animals extra-chromosomal DNA tends to be silenced, presumably to protect the cells from DNA viruses. Therefore if you want really good and stable production of a new gene product, you have to actually integrate the DNA into the chromosomes of the organisms. This requires that enzymes cut the host DNA and the plasmid, and then integration factors splice the plasmid into the chromosomal DNA. Unfortunately the enzymes which can accomplish this feat tend to be specific to closely related organisms, and if you wish to make good GMOs of new species, you have to set about discovering the appropriate enzymes. There are a host of other little details I could get into, but I think I will leave off at that for now.
  5. No. Apomixis offspring are genetically identical to their parents, whereas selfed offspring are genetically different from their parents as long as their parents are not totally inbred. To go through selfing you still have to make gametes, each of which contains a sub-sample of the parents genome, so selfed offspring become more inbred than their parents.
  6. Well, it depends on what resources you have available. There is a really cool seed germination experiment you can do. See this article on phytochrome http://en.wikipedia.org/wiki/Phytochrome, and you can pick up far red lights from many internet sources. You can look at a bunch of cool time laps photos of plant behaviours here: http://plantsinmotion.bio.indiana.edu/plantmotion/starthere.html One of my favourite is the video of the nastic movements of Morning glory. It spins around searching from something to wrap-around for support as it climbs. What kind of questions do you find interesting?
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