Tuesday, February 15, 2011

Biological Vignettes

I have been writing a series of short essays on topics covered in my biology class for extra credit. They are pretty basic, but the research is good, so I thought maybe some of you may find them interesting.

The first is on telomeres which are essentially junk DNA that is added onto to helix ends to protect your DNA from getting lost during replication.

Aging is an inevitable truth, and the search to reverse this has been long and futile. But scientists are coming closer to understanding why. It seems our DNA has an expiration date. And once this is hit, coding sections are dropped, miscoding for proteins begin to occur and diseases begin to pop up more often, and people begin to show signs of serious age.

Human DNA is protected at each end of each chromosome with repeat non coding nucleic acids hundreds of codes long. As cells divide, so does DNA, and when it is replicated from the parent strand only one end is left whole, the 3’-5’ coding side which runs in the opposite direction needed for DNA polymerase, requires a primer to start each segment and ends up dropping the last set during replication. Due to this lagging strand drop, each time a cell replicated one half of the DNA is shortened. Once the telomeres have all been dropped off, DNA starts getting dropped in replications, errors begin to occur and cell, due to complex regulatory and trigger mechanisms destroy themselves.

The most rapid growth of the human body is during the stages of development, and luckily these cells are protected by enzymes called telomerase which bind the telomeres to DNA and protect the rapidly dividing cells of embryos. Many studies have focused on gene therapy putting telomerase in adults organisms, and while it has shown some minor results in reversing aging in lab mice. However higher levels of telomerase in adult humans have shown a significant link to cancer. And recent studies of sea birds have shown no tie to telomere length or telomerase concentration in the bird’s physical age.

Continued study of the connection to telomere length, telomerase concentration and aging in eukaryotic organisms will probably go on for decades before it is fully understood. Whether or not that means a cure for aging can be found is unknown, for now all that is known is that in humans there seems to be a connection between the two.

Source : http://en.wikipedia.org/wiki/Telomere

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