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20 amino acids

_Rusty_

Volunteer Team

I know why there is 3 codons per AA, but why 20 AA?

Reply 1

avery_

Original post by chris01928

I know why there is 3 codons per AA, but why 20 AA?

this is one of those 'biological facts' you have to just take as true, especially at a-level and gcse. scientists are still investigating this to this day!

2 key answers are:

1. 20 amino acids is simply sufficient, using just 20 amino acids - all the organisms on earth have managed to adapt to almost every habitable environment.
2. the point at which tRNA (molecules involved in translation, which recognise codons) starts finding it difficult to distinguish different amino acids is 20.

both these points allude to the fact that 20 is simply sufficient for life.

hope this helps :smile: