Genetic code

• The genetic code may be defined as the exact sequence of DNA nucleotides read as three letter words or codons, that determines the sequence of amino acids in protein synthesis.
• In other words, the genetic code is the set of rules by which information encoded in genetic material (DNA or RNA sequences) is translated into proteins (amino acid sequences) by living cells.

Main points related to genetic code

1. The genetic code is ‘read’ in triplets of bases called codons. In other words, a set of three nucleotide bases constitutes a codon.
2. In a triplet code, three RNA bases code for one amino acid.
3. There are 64 codons which correspond to 20 amino acids and to signals for the initiation and termination of transcription.
4. The code uses codons to make the amino acids that, in turn, constitute proteins.
5. Each triplet [codon] specifies one amino acid in a protein structure or a start signal or stop signal in protein synthesis.
6. The code establishes the relationship between the sequence of bases in nucleic acids (DNA and the complementary RNA) and the sequence of amino acids in proteins.
7. The code explains the mechanism by which genetic information is stored in living organisms.

Properties of genetic code

a) Composed of nucleotide triplets.

b) It is non overlapping.

c) It is comma free

d) It is degenerate

e) It is ordered

f) It contains start and stop ends.

g) It is nearly universal

h) It is essentially non ambiguous under natural conditions.