Why have we only 4 DNA Bases on Earth???...

[Koni]

Why have we only 4 DNA Bases on Earth and NOT the theoretical possible 12 DNA Bases???...

Life on Earth has only 2 DNA Base pairs... (2 * 2 = 4 Bases)

Theoretical there could be 6 DNA Base pairs of pyrimidines and purines!!!... (6 * 2 = 12 Bases)

My sugestion is that if Life evolved from only pyrimidines and NOT purines,

then they are only 2 DNA Base pairs possible!!! (image)

 

[John Cuthber]

A larger number of bases means they have a bigger risk of being mistaken for one-another.

It's a trade off between data storage density and copy error rate.

 

Evolution thinks that 4 is the right number, and it has about a billion years of data to support this.
What evidence do you have that it is wrong?

[Koni]

I don't say that Evolution is wrong!!!...

But why - could we ask then - is there NOT only ONE Base pair ( = 2 Bases) enough???...

But why - could we ask then - are today by Synthetic Biology THREE Base pairs ( = 6 Bases) possible???...

My sugestion is only a possible answer why the only Bases are GC and AT...

( THANK YOU for your comments!!!...)

 

[fiveworlds]

Actually modern journals have mention 7 bases maybe even 8 but they are still undergoing a lot of research (https://www.sciencedaily.com/releases/2011/07/110721142408.htm)

The named bases are as follows

5-hydroxymethylcytosine

5-Methylcytosine

5-formylcytosine

5-carboxylcytosine

Basically just marginally different versions of cytosine.

 

[Koni]

How much different DNA Bases could you make using only pyrimidines???...

The answer is only 4 !!!

This is only a strange coincidence which make you to think about it...

[CharonY]

17 hours ago, Koni said:

But why - could we ask then - is there NOT only ONE Base pair ( = 2 Bases) enough???...

How do you want to encode 20 amino acids like that?

[Koni]

with 6 t-RNA codons (image)... 2⁶ = 64 !!!

[John Cuthber]

You could use just 1 pair, but the "words" would need to be a lot longer so- as I already pointed out- the risk of copy errors increases.

(effectively the 2 bases would be the 1 and 0 of a binary code.)
It's messy, but possible.

It would also need a "reading" mechanism that could encompass 6 bases at a time to "read" each codon.

 

It seems evolution got past "first base" a long time ago.

 

[Koni]

I agree with you but theoretical it could - in another Earth - be a seldom possibility...

Until we find LIFE in other Planets we cannot make conclusions about the LIFE in the Univerce!!!...

We can only speculate about the theoretical implications of what we know on Earth!!!...

(THANK YOU for your post!!!...)

 

[CharonY]

Now think about the error rate when you have runs of identical bases.

[Koni]

_{I agree with you because by Life you have always to deal with "Trade offs" !!!}

But we still don't know how is Life in other Planets !!!...

(THANK YOU for your post!!!...)

[Koni]

I thought about the problem of tautomerism and mutations rate...

Probably 4 Bases are the LIMIT that Life can accept!!!... (Image)