Telomeres – A Key to Aging?
In each of the human body’s cells there are 23 chromosomes, which are twisted, double-strands of DNA molecules. Chromosomes are vital as they provide our singular genetic map to every cell within our body. Lucky for us, on the ends of each of our chromosome strands sits a protective cap called a telomere. This cap protects our genetic data and literally keeps our chromosome DNA strands from fraying, becoming dysfunctional and even dying.
You can think of a telomere as the plastic tips on both ends of a pair of shoelaces. Without the reinforced tip the shoelaces will fray and not perform well. Without telomeres the chromosome ends will fray and even stick to each other, destroying genetic information (or causing corrupted genetic information to be passed along).
Every time our cells replicate themselves – which is constantly happening in many cells throughout the body in order for us to live – our telomeres get just a little bit shorter. Eventually the telomeres get too short to function, causing the cell to age and then stop functioning altogether.
So our telomeres shorten naturally as we age chronologically.
Scientists have also found that along with our chronological age, there are other factors that contribute to shortened telomeres, such as stress, a poor diet/obesity, lack of exercise and smoking.
Do shorter telomeres result in aging? Or does aging result in shorter telomeres?
Scientists have done a lot of research on telomeres. The question they have looked at is whether shorter telomeres actually cause aging, or are shorter telomeres just another marker for aging, like grey hair?
Scientists don’t have the answer to this question as yet, but the two (shorter telomeres and aging) are definitely linked. Laboratory and clinical research have proven linkages across many studies.
As one simple example of how aging and telomere length are connected, in white blood cells, normal telomere length ranges from 8,000 based pairs in newborns, to 3,000 based pairs in adults, and as low as 1,500 in the elderly.
A chromosome has some 150 million base pairs to start with; with cells normally dividing about 50 to 70 times. In all cells that normally divide, telomeres shorten with these divisions. Note that some cells in the body, such as heart muscle, do not divide and do not show decreases in telomere length with age.
In younger cells, an enzyme called telomerase keeps telomeres from shortening too much, but as cells divide there is less telomerase with each division; there is also a decrease in telomere length.
The importance of telomerase in species survival, health and cancer
Scientists have looked at the role of the enzyme telomerase in both healthy and cancerous cells.
In reproductive cells (sperm and egg cells), there is a high level of telomerase, which helps maintain telomere length. This ensures healthy cells are passed from one generation to the next. Scientists believe that this supports species survival.