Re: How might a human be cloned?

2.4.99

Dear Anne,

Please tell me how DNA matching/testing is done?

There are many methods.  Let's just go over one of them.  All humans have
nearly the same genetic code over the 3 billion nucleotides of the genome.
If you look for differences between two people you'll find them ever 1000
units or so.  Certain areas of the genome are more likely to vary - such
as areas where the DNA has lots of little repeats - the number of repeats 
can vary between people.  So how do we detect those difffernces?  One way
is to use a technique called polymerase chain reaction (PCR) to amplify a
variable region from DNA isolated from individuals. The region can then be
sequenced to see the exact differences or it can be monitored more crudely
for size differences between the amplified pieces.  Remember that humans
are diploid, getting one set of genes from the father and one from the 
mother.  So for any one person their could be two versions (alleles) at any
one variable site. 

Tell how a human might be cloned? Is this reasonable; getting a fertilized 
egg and waiting for it to divide, then spliting the eggs so now you have 
two fertilized and doing this process many times?  Then putting the 
fertilized eggs into many different women?  Would these women have children 
with the same DNA?  If this process is reasonable please explain in detail 
how this might be done?

Three years ago I would have told you that human cloning was unlikely.  But 
with the breakthroughs in sheep, cows, mice, etc. I don't see any 
scientific obstacles to human cloning.  (Not that I think its a wise idea.)  
Rather than telling you the whole method, let me refer you to the answer.  
The sheep cloning "Dolly" paper came out in the journal Nature.  Its not 
that hard a paper - a high school student should be able to read it with 
some help from a teacher.  The paper reference is 

Nature 1996 Mar 7;380(6569):64-6 
Sheep cloned by nuclear transfer from a cultured cell line.
Campbell KH, McWhir J, Ritchie WA, Wilmut I

Any college in Vancouver will have it in the library.

What scientific information is there on personality traits in your genes 
versus in the way you were brought up?  In other word nature versus 
nurture?

I don't really like this nature versus nurture split, because the answer
always has been and always will be that both things matter, its just a 
matter of degree.  Let's just pick one important behavior for which we
have some data - alcoholism.  Sons and daugthers of alcoholics are more
likely to be alcholic than a random person, even if they are raised away
from their parents. This suggests a genetic component.  Some papers 
indicate that one gene involved in the D2 dopamine receptor gene.  But 
obviously there is an environmental component too - if someone who is
likely to become an alcoholic is raised in a society without alcohol
this behavioral trouble will never be seen.

Hope this helps.

Jim McCarter, MD, PhD
 Genome Sequencing Center

-----