Why do we grow old and die ?

The cause of what we call "aging" is now being understood.
Dr. Langmore and his group looked inside human cells, at the very essence of human life: the DNA molecule. Specifically, Dr. Langmore looked at the tips of the DNA molecule -- a previously overlooked part of the double-helix molecule -- that contain a kind of chain of repeating pairs of enzymes.

Calledtelomeres, these molecular chains have often been compared to the blank leaders on film and recording tape. Indeed, telomeres seem to perform a similar function. During the replication process the spiral DNA molecule must split in half and reassemble a copy of itself. Protecting the vital DNA molecule from being copied out of synch, telomeres provide a kind of buffer zone where mis-alignments (which are inevitable) will not result in any of the important DNA code being lost.

Perhaps the best analogy I have heard is to compare the telomeres to the white margin surrounding an important type written document. In this analogy, the printed text is the vital DNA code while the white space is the "blank" telomeres.

Imagine that this paper is repeatedly slapped on a copy machine, a copy is made, and then that copy is used to make another copy. Each time the paper is subject to errors of alignment and these errors accumulate.

After enough copying, it is probable that the white space will diminish and some of the actual text will not be copied. That's what happens inside our cells and it is the reason we get old and die.

As any cell gets older, it is under attack by oxides and free-radicals in the body and environment. We survive as living beings because our cells have the ability to duplicate and replace themselves before being killed by these natural causes.

Each time our cells divide, the DNA molecule makes a new copy of itself. [Right:DNA is a complex molecule that resembles a spiral ladder. When it divides, it splits along the "rungs" then each half of this "ladder" rebuilds the missing half --viola!-- two DNA molecules. Now the cell can divide. The old cell dies and the new cell continues on.]

But the procedure is very complex and not perfect. Usually a small portion of the DNA molecule is lost, misaligned and not copied. Since errors are more frequent on the ends of the DNA molecule, this area, the telomere, does not contain any important DNA information and the effect is insignificant.

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