When you die, is your DNA the exact same as it was when you were born?
DNA contains a sort of genetic clock that changes as you get older. Apart from that it stays the same.
I think this is a really interesting subject. Parts of your body age differently based on the lifespan of the appropriate cells, as each time a cell dies one has to split, creating two copies of copies. For instance, humans shed their outer layer of skins many times a year, leading to skin apearing visually aged relativly early in life. Brain cells, however, are among the longest lasting cells in our bodies. They live for an average of 40 years (no cite here, notes from biology class), at which point inferior replicas must be made. So people, barring disease, will go into ther 50’s with many signs of aging, but very little change in their brains.
Now in theoretical mathmatics, it is said that the top minds in the field peak no later than 26. After that, they won’t make any greater controbution to mathmatics because they’ve lost the edge, the infintessimal difference that allowed them to see further than any before them.
In basketball, for instance, men’s bodies peak at 18-20. However, ninteen year olds aren’t running amok in the NBA dunking over the vets. The rate at which we accumulate knowledge and skill, then, must be added to the equation if we want to find out humans’ actual age of peak intelligence.
And there’s a lot of math to learn, and it’ll take awhile even if you’re a friggin’ genious. So maybe 26 is much older than this peak age.
So I’m 20 (on my dad’s account here), and I’m trying to eke out a living at poker. Poker is a game where that infintessimal difference could launch you from an honest living to Lifestyles of the Rich and Famous. Obviously there’s a lot to learn about poker, lifetimes worth, but the marginal value with respect to units of time will decrease rapidly. At what point will the derrivatives of the degradation of my brain cells and the accumulation of poker knowledge intesect?
It seems that point would be useful to know, because at that time I should be devoting my life to poker, ekeing out my best years for as much as their worth, like the mathamatictions do with theirs. Any thoughts on this ramble?
I thought brain cells did not reproduce?
Several things happen to DNA during replication. The biggest problem are mutation, oxidation, and telomere shortening. Mutation happens when one molecule is paired with a non-matching molecule. When one base is replaced with another, it changes the DNA code. Oxidation can prevent the DNA molecules from interacting with the proteins and replicating or expressing. Telomere shortening happens with every copy. The telomere is a nonsense sequence on the end of the DNA molecule. DNA replication cannot start at the first base, it has to start a number of bases in from the end. Since part isn’t copied, after enough replications, the nonsense telomere is gone and actual sense area start to be skipped during copying. Imagine publishing a novel, but every copy is missing a page at the front. The first copy would be complete, the second copy would miss that blank page, the third the title page, the fourth the table of contents, the fifth the forward, the sixth, the first page of the actual text, etc. After a while, the book wouldn’t make sense anymore.
However, if you killed someone yesterday and they found and preserved your blood at the crime scene and arrested you 60 years from now, your DNA would still be close enough to match and convict you.
I was taught that in school, too, usually as part of a “don’t drink because it kills brain cells that never come back” lecture.
Apparently, though, they’ve discovered in the last couple decades that they were wrong, and brain cells are replaced as we age.
Fine, but… Are they actually replaced by “inferior copies” (looking at my birth date and anxiously waiting for a reassuring response instead of “your brain will soon be replaced by an inferior copy”)?
Without looking it up, my recollection is that replication (i.e., cell division) introduces errors at a rate of 1 per million to 1 per 100 million base pairs. The human genome consists of about 3 billion base pairs. Telomere shortening has already been mentioned in this thread. UV and ionizing radiation can cause DNA damage, as can some chemicals and viruses.
If they didn’t, how could a newborn child grow up to an adult with an adult sized brain?