If more than one codon codes for same amino acid, this phenomenon is known as?
3 out of 64 codons do not code for any amino acid. These have been termed nonsense codons. These nonsense codons are utilized in the cell as termination signals; they specify where the polymerization of amino acids into a protein molecule is to stop. The remaining 61 codons code for 20 amino acids. Thus, there must be degeneracy in the genetic code, ie; multiple codons must decode the same amino acid. Some amino acids are encoded by several codons; for example six different codons, UCU, UCC, UCA, UCG, AGU, and AGC all specify serine. Other amino acids, such as methionine and tryptophan, have a single codon. In general, the third nucleotide in a codon is less impoant than the first two in determining the specific amino acid to be incorporated, and this accounts for most of the degeneracy of the code. However, for any specific codon, only a single amino acid is indicated; with rare exceptions, the genetic code is unambiguous--that is, given a specific codon, only a single amino acid is indicated. The distinction between ambiguity and degeneracy is an impoant concept. Ref: Weil P. (2011). Chapter 37. Protein Synthesis & the Genetic Code. In D.A. Bender, K.M. Botham, P.A. Weil, P.J. Kennelly, R.K. Murray, V.W. Rodwell (Eds), Harper's Illustrated Biochemistry, 29e.
Degeneracy
Frameshift mutation
Transcription
Mutation