Science of Aging has always fascinated scientists. why do we age? In 2009, 3 biologists, namely Elizabeth Blackburn, Carol W. Greider and Jack W. Szostak, received Nobel prize in physiology and Medicine for their research on end parts of chromosomes, called telomere which explains why do we age. The end part of Chromosomes act as bodyguard and protects DNA. On each cell division, a small part of telomere is chopped off. once the whole telomere is chopped off, cells die. one organism is immortal: tetrahymena, and secret lies in it having a enzyme telomerase which keeps rebuilding telomere. So they live forever. can we make telomerase for us also?
We all want to be youthful and look young. It’s a million dollar market investing in anti-aging creams and surgeries. It’s a big quest for biologists as well to explore in detail-
what causes aging?
Our bodies grow by dividing cells. Every time a cell is divided, all of the DNA, all of the code has to be copied because it contains all the instructions for cell to work in good order. We can’t risk to miss a single code from DNA. So, it also has its own bodyguard.
Long strands of DNA are actually tightly packed in a condensed form called Chromosomes. Now at the terminals of the chromosomes are structures called telomeres. They are DNA’s bodyguard.
Image credit : Genome Research limited
Telomeres : they are also made of DNA but are a repetitive sequence of the same code all over about 2000 times.
Whenever a chromosome is replicated, a part of telomere sequence is chopped off. But we don’t care, because it has the same code several times. So if we miss some of it, we still have the remaining. Also, it is non-coding i.e it does not provide information to process/synthesize biological products. Its purpose is protection.
Thus, on every division the length of telomere keeps on decreasing. And then comes the time when the whole telomeric section is striped off. At this stage cell stops dividing because if they still divide, they can miss out some important DNA at the end as there is no telomere (repetitive sequence) present. A miss of even a single code of DNA can lead to many problems
This is called cellular senescence. The cell dies or no more divides.
When majority of the cells in the body reach this stage, we die of old age.
Here’s some mathematics of it.
The length of DNA is measured in the units of Base pairs. In the embryonic stage there are 15,000 base pairs in our telomere. At the time of birth, we have 10,000 left. Cell dies when there are only 5000 left. Every year we lose 40-50 base pairs.
So theoretically , maximum age of human is 120 years.
Tetrahymena is immortal. Why?
One of the significant discoveries made by 2009 nobel prize winners is that , some organisms like tetrahymena have a enzyme called telomerase which rebuilts the chopped off section of telomere everytime cells divide. So, their telomeres never shorten and thus they live forever.
So why dont we make telomerase instead of anti-aging creams?
According to the research, telomerase enzyme is also present in our cells but it resting/sleeping stage. Its still a secret how to activate that enzyme. So if we somehow activate telomerase enzyme , will we be also immortal? Let a perfect scientific research answer that in upcoming years.
Till then, wish you long telomere.