Problems with Cloning

Factual Questions
1

Now,

I am not a biologist but I know the basic idea behind modern cloning technologies. You take a fertilized egg, remove the nucleus, take a certain kind of non-reproductive cell from the clonee and you implant its nucleus that into the egg as if it was supposed to be there. Thereby raising a clone - essentially IVF with a twist.

Now, here and there I keep hearing about health problems and such (reduced lifespan, etc.) that cloned sheep tend to have. My only guess as to why this would even happen is that either nuclei of grown cells are in some way not meant to be reproductive (i.e. pieces missing, or pieces too old/copied too many times) or that the cloning process itself somehow damages the nucleus and ruins the genetic code.

Now, why do these health effects occur? What ramifications does this have for human cloning? Is perfect cloning ever going to be possible?

Thanks,

Groman

P.S. A bonus question: Would it ever be possible to clone a male subject into a female one by copying over the X chromosome over the Y?

2

You are pushing the limits about what we answer right now. Your questions are a good guide to what scientists are working on finding out but no one has the answers. Some research has shown that clones do not have any more genetic diseases or shorter lifespans than non-close but the research is still inconclusive.

3

When you slap a sheep nucleus into a lizard’s egg cell you end growing a sheep with hybrid lizard/sheep mitochondria. Some mitochondrial enzymes are coded for in nuclear DNA, some in mitochondrial DNA, and some contain subunits from each source. The hybrid mitochondria may not work as well as a mitochondria from either source animal, as you’ve mixed evolutionarily distant enzymes.

4

There is a sort of genetic clock in cells, ticking downwards throughout life governing the aging process. http://www.infoaging.org/b-tel-home.html

The theory goes that if you take genes from an adult and produce a clone from them, then the clone will essentially be born old. The genetic clock will show an age much older than the actual age, leading to geriatric problems at a relatively young age.

AIUI, this hasn’t been proved, it’s only a theory. There has only been one successful cloning, and several hundred failed ones that were badly mutated and died quickly. The single successful clone did have a shorter than average lifespan, but it’s not certain that all clones would suffer the same fate.