Telomeres and DNA degradation, simplified
I have recently come across the creationist’s “degradation of the DNA” argument. Some creationists claim that owing to the nature of our telomeres, DNA degrade over the generations, making evolution more than impossible. I spent some time researching this matter and came up with interesting results; I would like to share them with you all!
What are telomeres?
Telomeres are regions of repetitive DNA found at the ends of chromosomes. Due to the way that cells split, information at the chromosomes’ ends are lost. Telomeres are repeats of DNA, which ensures that information is not lost during the split.
Telomeres shorten over time.
The next concept to grasp is that telomeres generally shorten over time. The creationists got this right (what a great surprise!). Telomeres shorten at every cell division (this also explains why cells age). But why do telomeres shorten? During division, the DNA’s two strands unwind, and two new strands come into match with the existing base pairs. This is done with the help of RNA, and RNA occupies a space at the end of the chromosomes. That occupied space is left untouched at the end of the process. After many divisions, one can see why telomeres would shorten, and when it runs out: wah-lah, DNA degradation!
Introducing the telomerase.
Telomerases are enzymes which extend the length of telomeres. There is a limited supply of these enzymes in older cells, therefore telomere shortening is somewhat inevitable, and the creationist’s claims still hold… But! Here’s the twist:
“Telomerase remains active in sperm and eggs, which are passed from one generation to the next. If reproductive cells did not have telomerase to maintain the length of their telomeres, any organism with such cells soon would go extinct.” – Lee Siegel, University of Utah
So consider again the replication of cells, this time with the advantage of the telomerase. Immediately the creationist’s argument falls into pieces.
We ought to love these telomerases, without which eukaryotes could not have easily evolved (prokaryotes – eg. bacteria – have circular chromosomes, so there are no chromosome ends for them to worry about). On a different note, telomerases are activated in cancer. Cancerous cells are, like other cells, subject to telomere shortening, however, if telomerases are activated, then they become immortal cells, so to speak. Perhaps the biggest key to curing cancer is to figure out how to deactivate these telomerases altogether!
Incidentally, this year’s Nobel Prize in Physiology or Medicine went to Blackburn, Greider and Szostak for the discovery of ‘how chromosomes are protected by telomeres and the enzyme telomerase’.
In summary, telomeres do shorten, but telomerases extend the telomeres during reproduction, therefore DNA’s do not degrade down the generations as the creationists claim. And if the creationist should like to use the telomerase as an example of intelligent design, remember that this troublesome, shortening telomere is already a blatant example of unintelligence. God bless.