In humans, there are 46 chromosomes, arranged into 23 pairs. When our cells are ready to replicated, such as in mitosis, our chromosomes (which are made of bundled up DNA) become visible under the microscope. These chromosomes carry all of our genetic information, but they need to be protected.
This is where telomeres come in. Telomeres are repetitive sequences of DNA which sit on the end of our chromosomes, and they protect the genetic information from being damaged during cell replication, where there’s a risk that the chromosomes could fray or stick together and become damaged.
A good analogy for a telomere is the plastic bit on the end of a shoelace, it’s hardy and protects the ends of the strands from breaking.
But, telomeres don’t last forever. Every time our cells and our chromosomes replicate, a small portion of each telomere is lost. Eventually, they become too short to keep a cell safe, and so the cell either becomes static, meaning that it stays alive but no longer divides, or it undergoes apoptosis, which is cell death.
So telomeres are actually involved in the ageing process, but they can also be part of the key to immortality. Cancer cells for example, don’t age, and in the right conditions they can carry on replicating forever. But how? Well, it’s because they are able to use an enzyme called telomerase, which maintains telomeres are healthy lengths.
There’s a lot more that we can learn from telomeres and telomerase, at some point, scientists may be able to block the action of telomerase and therefore stop cancer cells from endlessly replicating, and they may also be able to help with other diseases associated with ageing.
The odds are that many people haven’t heard about these little telomeres, but they play a big part in our lives, and our ages.