Genetic code is a sequence of three nucleotides on DNA or mRNA, codes for a specific amino acids for protein synthesis. 

Features of Genetic code 

• Genetic code is triplet: Each codon consists of sequence of three nitrogen bases. 
• Genetic code is universal: A particular codon codes for the same amino acid in all organisms. 
• Genetic code is non overlapping: The successive triplet codons are read in order without overlapping and they do not share any base. 
• Genetic code is degenerate: A single amino acid is coded by more than one codon. 

Example : valine is coded by 4 different codons GUA, GUC, GUU and GUG 

• Genetic code is commaless: Codons are without punctuation and written in linear form. There is no signal to indicate the end of one codon or beginning of the next codon. 
• Genetic code is non-ambiguous: Each codon specifies a particular amino acid in all organisms. 

Example : AUG codes for methionine . 

• Initiator codons: Protein synthesis is always initiated by particular codons called initiator codons. 

Example : AUG in eukaryotas, GUG in prokaryotes 

• Terminator codons: Three codons that act as stop signals to terminate protein synthesis are called terminator codons or nonsense codons.

Example: UAA (Ochre), UGA (Amber) and UGA (Opal).