A MICROBE found in cows’ stomachs is forcing biologists to broaden their ideas about the genetic code. Its DNA codes for a previously unseen amino acid, suggesting that the genetic code is richer than anyone realised.
The genetic code consists of sequences of the four DNAbases, A, C, T and G, grouped into threes. Each of these triplets either codes for an amino acid or tells the RNA apparatus that translates the code into protein where to start or stop. Biologists once believed that DNA codes for only 20 different amino acids, but in 1986, they found a 21st.
Now…
