How long do cells live (fork)

[tomBitonti]

Forked from

http://www.enworld.org/forum/showthread.php?467093-Is-Global-Warming-real

In particular:

That's fine. The half-life of DNA, even in bone or trapped in amber, seems to be about 520 years or so. A 65 million year old dinosaur cell has gone through about 125,000 half-lives. Thus the amount of DNA has been cut in half 125,000 times, leaving nothing useful.

The question is, how long do cells live? In a 500 year old tree, are any of the tree's living cells 500 years old?

My understanding is that humans don't get new nerve cells, so a 100 year old person will have 100 year old nerve cells. If this is true for tortoises, does that mean there can be 200 year nerve cells? What is the limit?

Thx!

TomB

 

[Dannyalcatraz]

Depends on the cell:
http://www.smithsonianmag.com/science-nature/henrietta-lacks-immortal-cells-6421299/

 

[tomBitonti]

That's interesting, but the link is actually about cell lines.

I though that most human cell lines will die out due to apoptosis (programmed cell death).

Now, if a cell divides, do you include that in the age of the cell? Or does the clock start anew?

The genetic material will have divided, so the new cells are arguably "new" cells, but maybe you could argue otherwise.

Thx!

TomB

 

[Dannyalcatraz]

True.

Individual cells don't live very long...compared to the entity they're a part of. They also have differing lifespan depending on function. Some live only days, others, years

https://www.timeshighereducation.co...re-younger-than-the-individual/198208.article

 

[tomBitonti]

True.

Individual cells don't live very long...compared to the entity they're a part of. They also have differing lifespan depending on function. Some live only days, others, years

https://www.timeshighereducation.co...re-younger-than-the-individual/198208.article

Ah:

Dr Frisén and his team looked at tissue samples from more than a dozen deceased subjects, about half of whom were born after the mid-1960s.

Each kind of tissue has its own turnover time, related at least partially to the workload endured by its cells. Epidermic cells, forming the easily damaged skin of the body, are recycled every two weeks or so. Red blood cells, in constant motion on their journey through the circulatory system, last only 4 months. As for the liver, the human body's detoxifier, its cells' lives are quite short - an adult human liver cell has a turnover time of 300 to 500 days.

Cells lining the surface of the gut, known by other methods to last for only five days, are among the shortest-lived in the whole body. Ignoring them, the average age of intestinal cells is 15.9 years, Dr Frisén found. Skeletal cells are a bit older than a decade and cells from the muscles of the ribs have an average age of 15.1 years. When looking into the brain cells, all of the samples taken from the visual cortex, the region responsible for processing sight, were as old as the subjects themselves, supporting the idea that these cells do not regenerate. 'The reason these cells live so long is probably that they need to be wired in a very stable way,' Frisén speculates. Other brain cells are more short-lived. Dr Frisén found that the heart, as a whole, does generate new cells, but he has not yet measured the turnover rate of the heart's muscle cells. And the average age of all the cells in an adult's body may turn out to be as young as 7 to 10 years, according to him.

Thx!

TomB

 

[Umbran]

Now, if a cell divides, do you include that in the age of the cell? Or does the clock start anew?

Well, consider - if you don't start the clock over at some point, then all cells are basically immortal. Life is a continuous chain since it's inception some 3.5 or more billion years ago, and if you never restarted the clock, all your cells are that old.