lengthens the buffer sequences at the tips of chromosomal DNA

The protein, Telomerase is a protein that elongates the ends of chromosomal DNA with a repeated sequence. The DNA telomerase adds does not carry protein-coding information, rather it is a generic repeat used to shield the information-coding DNA. The aglets on your shoelace (hard plastic tips) act to protect the fabric of your shoelace in a similar manner as telomeres protect the DNA in your chromosome.

Telomerase the protein, together with a large RNA molecule, lengthen these telomeres by attaching repeats of non-coding DNA to the ends of chromosomes. Telomerase is mostly active in stem cells - those cells which whose job it is is to produce more cells, and is not found at high levels in most of the cells in your body. In most cells, the longer the telomere the fewer divisions the cell has undergone, or the shorter the telomeres, the older the cell.

Aging & Cancer

Because telomeres shorten as we age, and the protein telomerase lengthens telomeres, a basic hypothesis asks if we could use telomerase to prevent some of the effects of aging.

In most cancers, telomerase is often over-produced permitting the cancerous cells to forever continue dividing, unbounded by the Hayflick limit. This finding naturally complicates the above hypothesis about using telomerase to prevent the effects of aging.

Nobel Prize

The 2009 Nobel Prize in Medicine was awarded to Elizabeth Blackburn, Carol Greider, and Jack Szostak for the discovery of telomeres and telomerase.