genetic engineering - (Jun/19/2007 )
1. Why if people want to clone a sheep, they have to find a surrogate mother? I think they can just take the mammary cell from the donor mother, then take out donor mother's nucleus in its egg cell, then put her own mammary cell into the egg cell, that's it!? why should they use surrogate mother to do that?
2. What's is artificial selection? it means humans select certain animals to breed?
Thanks for help!
It makes seeing a positive result easier to see. Dolly's was a Finnish Dorset, while her surrogate mother was a black face ewe. THe animals are pigmented differently (all white vs black face), so a simple glance and you can tell if your method worked. If 6LL3 (Dolly's biological nuclear donor) had given birth to Dolly, you won't be able to tell just by looking. Futhermore, it would be a longer process to genetic finger print Dolly, to make sure she wasn't a normal daughter of 6LL3. Afterall a child has half their parents DNA.
2. What's is artificial selection? it means humans select certain animals to breed?
Thanks for help!
"artificial selction" = breeding
Artificial selection is something people have been doing for the last thousands of years. It's done both with plants and animals.
Basically you select the most interesting specimens (with above than average characteristics) and allow them to mate. The probability that the progeny will also have those desired characteristics is higher than to cross random individuals. You can do this every generation, in order to have animals/plants that are more interesting from a agronomic/comercial point of view.
It's a way to speed up and direct selection according to your needs.
MIA6 makes a good point, though. I think MIA6 is referring to the source of the donor nucleus and the source of the acceptor egg cell. Why not use the same animal? You could then implant the egg into a different breed for visual identification. The big advantage, in my mind, would be the production of a true genetic clone. Dolly was only a nuclear clone. Her mitochondrial DNA came from a different animal. The products of nuclear and mitochondrial genomes do interact to produce a specific phenotype, so Dolly and a hypothetical true-clone sister might show some phenotypic differences that would be due to their different mitochondria.