Same amino acid is coded by multiple codons due to:(AIIMS May 2012, Nov 2011)
Ans. a. Degeneracy (Ref: Harper 29/e p190, 396, 28/e p354)Degeneracy is the redundancy of the genetic code, where more than one triplet codes one amino acid. (AllMS May 2012, November 2011, November 2006 Repeat)DegeneracyDegeneracy is the redundancy of the genetic codeQ.The genetic code has redundancy but no ambiguityQ.The codons encoding one amino acid may differ in any of their three positionsQ.There are three amino acids encoded by six different codons: serine, leucine and arginineQ.Only two amino acids are specified by a single codonQ.One of these is the amino-acid methionine, specified by the codon AUG, which also specifies the start of translation: the other is tryptophan, specified by the codon UGGQ.The degeneracy of the genetic code accounts for the existence of synonymous mutations.Degeneracy results because there are more codons than encodable amino acidsQ.CodonInitiation codon is AUG (Methionine)QTermination codons: UAA (Ochre), UAG (Ambre), UGA (Opal)QCharacteristics of the Genetic CodeThe genetic code is unambiguous: each codon specifies one amino acid onlyQ.The code is degenerate: One amino acid maybe specified by more than one codonQ.In most cases, the first two bases perform sufficient coding, the third (or wobble) base playing a minor roleQ.Codons with a similar sequence specify amino acids with similar chemical propertiesQ.
Degeneracy
Frame-shift mutation
Transcription
Mutation
Structure of DNA