A copy of a copy is never as good as the original

Our final discussion in Molecular Genetics (BIO 415) we finished up chapter 8 of Miesfeld’s, Applied Molecular Genetics, text. We explored the nitty-gritty details of cloning the first mammal, the sheep called “Dolly” as well as “Polly” and “Molly”…the transgenic cloned sheep.

Dolly, the first animal cloned from an adult cell

We also explored the limitations of cloning.  You see a copy of a copy of a copy is never as good as the original, and this holds true for DNA too.  Enter the function of telomeres and telomerase.  Each time DNA is replicated, you need a spot for the machinery of replication to attach to.  That space it attaches to can’t be replicated and it is lost so we’ve developed these stretches of sequence called telomeres which are non-coding regions of sequence that the replication machinery can sit down and attach to in order to begin replication on those coding regions that are so important for our proper existence.

Telomeres vary in size depending on age

So what I’m getting at here is that Dolly didn’t live as long as other naturally born sheep.  Even though she was a baby…her stock of DNA was older. You see during natural fertilization…you’ve got a lot of processes going on to ensure your telomeres are all in lengthy order…but Dolly started with an older aged stretch of DNA…telomeres had already been destroyed snippet by snippet over the years in her precursor’s cells.  She was old before she was even born.

A second topic brought up in our discussion of cloning was the behavior of the clone.  As we’ve discussed during our behavioral genetics unit in class…the argument of nature vs. nurture runs deep and is very complex.  Just because you share an identical genome with someone (as identical twins may) does that mean you act the same way?  We are products of a mixture of both our genes and our experiences.  While our genetic make up my help predict how we “might” act, it does not fully dictate our actions.  I think this is represented quite well in a “This American Life” piece. Check it out here.

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