Properties of genetic code and Wobble Hypothesis
Genetic code is the set of 64 nucleotide triplets that specify the 20 amino acids and polypeptide chain initiation and termination.
Properties of genetic code
- The genetic code is composed of nucleotide triplets. Three nucleotides in mRNA specify one amino acid in the polypeptide product.
- Francis Crick and colleagues in 1961 published the first strong evidence in support of a triplet code (three nucleotides per codon).
- Genetic code was cracked by the combined efforts of Marshall Nirenberg, Severo Ochoa, H. Ghobind Khorana, Philip Leder, and their colleagues who worked out the meaning of all 64 triplet codons .
- Nirenberg and Khorana shared the 1968 Nobel Prize in Physiology or Medicine for their work on the code with Robert Holley, who determined the complete nucleotide sequence of the yeast alanine tRNA.
- The genetic code is non-overlapping.
- The genetic code is comma-free.
- The genetic code is degenerate. The occurrence of more than one codon per amino acid is called degeneracy.
- The degeneracy in the genetic code is highly ordered.
- The genetic code is ordered
- The genetic code contains start and stop codons
- Start codon: AUG; GUG occasionally
- Termination codons: UAG, UAA, and UGA
- The genetic code is nearly universal