Thanks Judah. My wife read over both your posts too (being an anthropologist / archaeologist) and thoroughly enjoyed them. Very informative.
So if I read this right you are basically saying that Jerry is a fascist? /me runs away and high fives Eric on my way to go hide under a bridge. On Tue, Jun 8, 2010 at 12:05 AM, Judah McAuley <[email protected]> wrote: > > On Mon, Jun 7, 2010 at 5:51 PM, Medic <[email protected]> wrote: > >> > >> Hope that helps, > >> > > > > So is selective breeding actually considered genetic engineering? > > No, sorry, didn't mean to leave that impression. I'm not aware of > anyone who calls selective breeding "genetic engineering". Maybe > Monsanto, so they can give the impression that what they do is just > like what little 'ol farmers have been doing for generations. > > Selective breeding and genetic engineering work two fundamentally > different ways. Selective breeding starts with a phenotypically > desired expression, say sweetness in corn or small size in poodles. > They then take the offspring that best display those desired > characteristics (more sweet corn, smaller poodles) and breed those > together. Some percentage (often times a large percentage) of each > generation will not meet the desired characteristics and those are > discarded from the breeding pool. The downside to this method is that > you are essentially making a sort of founder event with each > generation because you are only breeding a small percentage of the > individuals. This has a tendency to amplify undesirable > characteristics as a side effect, like hip dysplasia in German > Shepards. > > Genetic engineering, by contrast, doesn't place the odds game with > each generation. If you want to have nice pink pea flowers and Gregor > Mendel tells you that 1/4th of your peas are likely to have pink > flowers when you breed two pink pea flowers because pink is recessive, > well, you're going to have to toss 75% of your offspring because they > won't have the phenotype you desire. Genetic engineering will, > instead, find the allelle(s) (which are variants of a gene, red hair > allelle, a blonde allelle, etc which are all the same gene but > different versions of it that produce different expression) that > encode the protein that turns the flowers pink and essentially paste > that version of the gene into seeds so that all the seeds will produce > pink flowers. The potential upside of this is that you could, > theoretically, have a wide variety of values for all the other genes > and only mess with the genes you are going after. This has the > potential to reduce the side effects seen in heavy selective breeding > (inbreeding). In practice, however, there are usually only 1 or 2 > strains of an organism that are produced through genetic engineering > as it is a pretty tech-intensive and R&D intensive process and as a > result, we end up with massive monocultures. And when everyone plants > the same thing, we lose the natural variability out in the genetic > pool for those organisms and they are susceptible to massive > disruption if something evolves to take out those 1 or 2 strains. > > Genetic engineering also works much better on plants which produce > asexually. You can modify its genetic signature and seeds produced by > it will largely adhere to that signature. Anything which reproduces > sexually is usually going to undergo the mixing of chromosomes during > egg and sperm combination (meiosis and mitosis) which will tend to > muddle things up. There are ways to overcome this and produce a child > of some species that is essentially a clone of the mother, but they > are really only used in basic research laboratory settings as far as I > know. > > The other type of genetic engineering I spoke of is transgenic > engineering. That is taking genetic sequences from one species and > splicing it into the genetic sequence of another. Some examples of > this are controversial, like the Bt spliced in corn that I mentioned. > Other examples are very routine these days, like the production of > human insulin. Insulin used to derived from animal sources, pigs and > cows mostly, as their insulin is almost, but not quite, exactly like > our own. This worked ok for most people but some people had bad > reactions to animal-based insulin. Then a couple decades ago, > scientists succeeded in attaching the human insulin sequence to E. > Coli and making it so it stays intact as the bacteria divide and still > express the protein for insulin and that is then collected and > refined, producing exact human insulin. > > So, yeah, I wouldn't call selective breeding "genetic engineering". It > also isn't inherently safer or better than genetic engineering. And > genetic engineering of a species to produce individual strains with > desired characteristics isn't the same as transgenic genetic > engineering. At this point, I'd say they all have their ups and downs > and transgenic engineering is the most unknown and gives me the most > pause, but it is a very rapidly advancing field and I'm certainly not > an expert. > > Hope that clears things up. > > Judah > > ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~| Order the Adobe Coldfusion Anthology now! http://www.amazon.com/Adobe-Coldfusion-Anthology-Michael-Dinowitz/dp/1430272155/?tag=houseoffusion Archive: http://www.houseoffusion.com/groups/cf-community/message.cfm/messageid:320602 Subscription: http://www.houseoffusion.com/groups/cf-community/subscribe.cfm Unsubscribe: http://www.houseoffusion.com/groups/cf-community/unsubscribe.cfm
