Does our DNA determine our lifespan?

Question

Apart from lifestyle factors such as diet, stress, toxins, is there something in our DNA that will determine how long each one of us lives?

In other words, is there a biological clock ticking in our DNA that determines the maximum age you can live?

Answer 1

Yes. The ends of your chromosomes of DNA are called your telomeres. They don't code for anything, but serve to protect your DNA coding for actual genes that are important. After many replications of a chromosome the telomeres shorten and segments are lost due to an enzyme called telomerase. Its job is to reduce the telomeres. After so many replications of the DNA, the telomeres are eventually gone, and the telomerase eats away at the DNA that codes for needed proteins. Without certain proteins, we cannot live. Thus, as people get older, their DNA has been replicated so many times that the lose enough vital proteins, and can no longer live. This is why people die of old age. Hence, the size of your telomeres on your DNA (inherited from your parents) determines how long you live. Longer telomeres = more uncoding segments = less genes lost after multiple replications = longer life.
This is why cancer cells can live forever, because they lack the enzyme telomerase.

Answer 2

I am soooo anti death penalty. And part of my reasoning is that there have been people who were later found innocent. That doesn't mean I want convicted murderers running free. I think it's a worse punishment to have to sit in a tiny jail cell for the rest of your life. (And there have been a lot more than two people who were found innocent.) I'm disturbed by your argument that these people are not and can never be normal, that they are not an asset to society. Couldn't you make the same argument for mentally and physically handicapped people? Do you think they deserve to die as well? As for the cost, housing prisoners does cost money. But if you want to talk about money, look at all of the programs that could be used that aren't being taken advantage of. It has been proven that college education systems in prisons dramatically lowers the recidivism rate. The cost of these programs is so much lower than the cost to keep prisoners when they come back after being released. Yet these programs aren't being utilized because of the upfront costs. Prisoners are a captive workforce, and still our government allows jobs to be sent overseas. Wouldn't this be a nice source of revenue for the prison system? And I have a big problem that so many death penalty supporters are of the Christian conservative/Republican variety. This group will use the argument that all life is sacred when it comes to abortion and stem cell research - why not in this circumstance as well?

Answer 3

By DNA you mean heridity, right? Because there are other traits inherent in humans that determine how long we live that are not truly heriditary. Anyway, heridity is only part of it. We can be predisposed (to a greater or lesser extent) to such things as heart disease, high blood pressure, cancer, etc. However, lifestyle is primarily to blame for illness. If we all ate right, were not overweight, didn't smoke and didn't ingest a bunch of junk that is harmful, we would be more healthy and live longer.

But only to a point. Our bodies wind down because at the cellular level we're unable to repair the degeneration that takes place over time due to the simple act of living. This may be simplistic, but it's how I view it.

Answer 4

In my limited understanding, yes.

Ignoring lifestyle, diet, drugs, and diseases (caught or inherited), I believe that there is a part of the DNA molecule that only allows itself to be replicated a certain number of times.

I think cancer is essentially when that 'switch' gets destroyed, and the cells will replicate endlessly - leading to tumours. This is why cancer only tends to affect certain organs or systems within the body. One particular cell, for example a lung cell, will start endlessly replicating.

Quite how this theory pans out over a person entire lifetime, I have no idea. I'm not even sure if anyone actually knows.

I'd be interested to see if anyone knows the answer for sure.

Answer 5

We have linear chromosomes that have ends called "telomeres". When the DNA replicates through mitosis, the ends (which are folded back on themselves) do not replicate and the chromosome becomes shorter each time.

There is a theory in biology that cells can only divide a certain number of times because of this shortening of chromosome, called the "Hayflick limit".

Cancers and stem cells both have mechanisms to keep telomere length upon replication and also both happen to be immortal.

I hope this helps!

Answer 6

Yes, it does. Every species is wired genetically to begin senescence within a certain range. Some organisms live lengthy life spans, and others only a few days.

Answer 7

Well, to a certain extent, I suppose. Genetic factors and all that.