I was eating with my dad, who is a biophysicist, and he brought up an interesting question for which I haven't found an answer. I thought maybe someone on HN would have heard something more.
Why, after billions of years of evolution, do we still have ALL known organisms still have 4 nucleotides? Yes, Uracil is used in RNA but it encodes the same information, ie why is it always base 4? How come a 5th nucleotide has never appeared, or any nucleotide become less prevalent?
It seems interesting that the genetic code is base 4. And are there really only 20 amino acids?
Why, after billions of years of evolution, do we still have ALL known organisms still have 4 nucleotides? Yes, Uracil is used in RNA but it encodes the same information, ie why is it always base 4? How come a 5th nucleotide has never appeared, or any nucleotide become less prevalent?
It seems interesting that the genetic code is base 4. And are there really only 20 amino acids?