Back in the 50's, a family member attended a lecture in Canada. The lecturer had a small briefcase with an unusual teaching aid- a bike chain.
The chain when twisted formed a double helix.
That lecturer was Francis Crick. Maybe you know the name? Crick and Watson are credited with the discovery of DNA structure. They were able to do so because of the work on DNA X-Ray crystallography by an uncredited scientist named Rosalind Franklin.
This is a top down look at the helix:
As you can see, the credit for the concept really goes to the lady.
Anyway, the original Watson-Crick paper had a startlingly correct insight.
The chemical structures of the 4 bases that make up the base pairs crosslinking in that X in the picture above have a property that drives mutations. This is one of the bases, Guanine:
Guanine base pairs with Thymine.
You can see the structure is 2 rings, one pentagon, and one hexagon. Every apex has a carbon atom, unless a Nitrogen one substitutes - you see the N's there.
This whole thing is held together by the interaction of the electron clouds around each atom. Atoms that end up sharing an electron are connected by a bond, shown as a line in the structure.
Because that is a quantum mechanism, there are some unstable characteristics.
It is possible that a shared electron in the cloud could take a position much closer to one atom than the other. So much so that the bond weakens. When that occurs, the bond stretches like a rubber band. And that distorts the shape of the structure. All 4 of the bases have ring structures, and undergo this effect periodically. That's a problem. But only if the train is on time.
This is a little train.
It chugs down a track, made of 2 metal rails with wooden cross pieces. That track is just like DNA structure, just flattenned out into a ladder. In our cells, proteins periodically slide along the DNA just like little trains going down tracks, looking for things to fix. If they find a mismatch or an error, they edit the DNA right there.
If that basepair happens to be a G-T pair, and at that moment an electron is in the wrong place, the structure is distorted, and the protein gets confused.
It's not very smart, so it does its one job, and edits the DNA.
And just like that, we have a mutation. Because when you edit the correct base pair, you introduce an error.
You may imagine the billions of base pairs, in your own DNA for a moment, repeated in every nucleus in every cell. It's flickering with these quantum alterations, and the consequent error rate is making us change. Making us age, and get cancer, yes, but also producing evolution on a grander scale.
Watson & Crick predicted this in 1953.
It was found to be true by observation in 2018.
The chain when twisted formed a double helix.
That lecturer was Francis Crick. Maybe you know the name? Crick and Watson are credited with the discovery of DNA structure. They were able to do so because of the work on DNA X-Ray crystallography by an uncredited scientist named Rosalind Franklin.
This is a top down look at the helix:
As you can see, the credit for the concept really goes to the lady.
Anyway, the original Watson-Crick paper had a startlingly correct insight.
The chemical structures of the 4 bases that make up the base pairs crosslinking in that X in the picture above have a property that drives mutations. This is one of the bases, Guanine:
Guanine base pairs with Thymine.
You can see the structure is 2 rings, one pentagon, and one hexagon. Every apex has a carbon atom, unless a Nitrogen one substitutes - you see the N's there.
This whole thing is held together by the interaction of the electron clouds around each atom. Atoms that end up sharing an electron are connected by a bond, shown as a line in the structure.
Because that is a quantum mechanism, there are some unstable characteristics.
It is possible that a shared electron in the cloud could take a position much closer to one atom than the other. So much so that the bond weakens. When that occurs, the bond stretches like a rubber band. And that distorts the shape of the structure. All 4 of the bases have ring structures, and undergo this effect periodically. That's a problem. But only if the train is on time.
This is a little train.
It chugs down a track, made of 2 metal rails with wooden cross pieces. That track is just like DNA structure, just flattenned out into a ladder. In our cells, proteins periodically slide along the DNA just like little trains going down tracks, looking for things to fix. If they find a mismatch or an error, they edit the DNA right there.
If that basepair happens to be a G-T pair, and at that moment an electron is in the wrong place, the structure is distorted, and the protein gets confused.
It's not very smart, so it does its one job, and edits the DNA.
And just like that, we have a mutation. Because when you edit the correct base pair, you introduce an error.
You may imagine the billions of base pairs, in your own DNA for a moment, repeated in every nucleus in every cell. It's flickering with these quantum alterations, and the consequent error rate is making us change. Making us age, and get cancer, yes, but also producing evolution on a grander scale.
Watson & Crick predicted this in 1953.
It was found to be true by observation in 2018.
A mutational timer is built into the chemistry of DNA
Scientists have discovered that DNA contains a kind of built-in timer that clocks the frequency with which mutations occur. They show that DNA bases can shape-shift for a thousandth of a second, transiently morphing into alternative states that allow the molecule's replication machinery to...
www.sciencedaily.com
