What is a Telomere?:
A chromosome is a long strand of DNA. At the end of a chromosome is a telomere, which acts like a bookend. Telomeres keep chromosomes protected and prevent them from fusing into rings or binding with other DNA. Telomeres play an important role in cell division.
What Happens When a Cell Divides?:
Each time a cell divides, the DNA unwraps and the information in the DNA is copied. The process does not copy all of the DNA information - the telomeres are not copied.
When the cell is finished dividing, the DNA comes back together. The telomeres lose a little bit of length each time this happens.
Why Do They Get Shorter?:
When a cell divides and copies DNA, the strands of DNA get snipped to enable the copying process. The places that are snipped are the telomeres. Since the telomeres do not contain any important information, more important parts of the DNA are protected. The telomeres get shorter each time a cell divides, like a pencil eraser, gets shorter each time it's used.
Can Telomeres Become Too Short?:
Yes. When the telomere becomes too short, essential parts of the DNA can be damaged in the replication process. Scientists have noticed that cells stop replicating when telomeres are shorter. In humans, a cell replicates about 50 times before the telomeres become too short. This limit is called the Hayflick limit (after the scientist who discovered it).
How Does All This Affect Aging?:
Researchers can use the length of a cell's telomeres to determine the cell's age and how many more times is will replicate. This is important in anti-aging research. When a cell stops replicating, it enters into a period of decline known as "cell senescence," which is the cellular equivalent of aging.
People with longer telomeres still experience telomere shortening as they age. How many years might be added to our lifespan by completely stopping telomere shortening? research suggests 10 years and perhaps 30 years.
Chronological Age
After age 60, the risk of death doubles every 8 years. So a 68-year-old has twice the chance of dying within a year compared with a 60-year-old. Cawthon's study found that differences in telomere length accounted for only 4% of that difference. And while intuition tells us older people have a higher risk of death, only 6% is due purely to chronological age. When telomere length, chronological age, and gender are combined (women live longer than men), those factors account for 37% of the variation in the risk of dying over age 60. So what causes the other 63%?
Oxidative Stress
A major cause of aging is "oxidative stress." It is the damage to DNA, proteins, and lipids (fats) caused by oxidants, which are highly reactive substances containing oxygen. These oxidants are produced normally when we breathe, and also result from inflammation, infection, and consumption of alcohol and cigarettes. In one study, scientists exposed worms to two substances that neutralize oxidants, and the worms' lifespan increased an average 44%.
Glycation
Another factor in aging is "glycation." It happens when glucose, the main sugar we use as energy, binds to some of our DNA, proteins, and lipids, leaving them unable to do their jobs. The problem becomes worse as we get older, causing body tissues to malfunction, resulting in disease and death. Glycation may explain why studies in laboratory animals indicate that restricting calorie intake extends lifespan.
Most likely oxidative stress, glycation, telomere shortening, and chronological age — along with various genes — all work together to cause aging.
Read more about Telomeres
Diet and Anti-Ageing
A chromosome is a long strand of DNA. At the end of a chromosome is a telomere, which acts like a bookend. Telomeres keep chromosomes protected and prevent them from fusing into rings or binding with other DNA. Telomeres play an important role in cell division.
What Happens When a Cell Divides?:
Each time a cell divides, the DNA unwraps and the information in the DNA is copied. The process does not copy all of the DNA information - the telomeres are not copied.
When the cell is finished dividing, the DNA comes back together. The telomeres lose a little bit of length each time this happens.
Why Do They Get Shorter?:
When a cell divides and copies DNA, the strands of DNA get snipped to enable the copying process. The places that are snipped are the telomeres. Since the telomeres do not contain any important information, more important parts of the DNA are protected. The telomeres get shorter each time a cell divides, like a pencil eraser, gets shorter each time it's used.
Can Telomeres Become Too Short?:
Yes. When the telomere becomes too short, essential parts of the DNA can be damaged in the replication process. Scientists have noticed that cells stop replicating when telomeres are shorter. In humans, a cell replicates about 50 times before the telomeres become too short. This limit is called the Hayflick limit (after the scientist who discovered it).
How Does All This Affect Aging?:
Researchers can use the length of a cell's telomeres to determine the cell's age and how many more times is will replicate. This is important in anti-aging research. When a cell stops replicating, it enters into a period of decline known as "cell senescence," which is the cellular equivalent of aging.
People with longer telomeres still experience telomere shortening as they age. How many years might be added to our lifespan by completely stopping telomere shortening? research suggests 10 years and perhaps 30 years.
Chronological Age
After age 60, the risk of death doubles every 8 years. So a 68-year-old has twice the chance of dying within a year compared with a 60-year-old. Cawthon's study found that differences in telomere length accounted for only 4% of that difference. And while intuition tells us older people have a higher risk of death, only 6% is due purely to chronological age. When telomere length, chronological age, and gender are combined (women live longer than men), those factors account for 37% of the variation in the risk of dying over age 60. So what causes the other 63%?
Oxidative Stress
A major cause of aging is "oxidative stress." It is the damage to DNA, proteins, and lipids (fats) caused by oxidants, which are highly reactive substances containing oxygen. These oxidants are produced normally when we breathe, and also result from inflammation, infection, and consumption of alcohol and cigarettes. In one study, scientists exposed worms to two substances that neutralize oxidants, and the worms' lifespan increased an average 44%.
Glycation
Another factor in aging is "glycation." It happens when glucose, the main sugar we use as energy, binds to some of our DNA, proteins, and lipids, leaving them unable to do their jobs. The problem becomes worse as we get older, causing body tissues to malfunction, resulting in disease and death. Glycation may explain why studies in laboratory animals indicate that restricting calorie intake extends lifespan.
Most likely oxidative stress, glycation, telomere shortening, and chronological age — along with various genes — all work together to cause aging.
Read more about Telomeres
Diet and Anti-Ageing