Genetic code

GENETIC CODE

The genetic code refers to the relationship between a particular sequence of nitrogenous bases from the mRNA and the amino acids that form a particular protein. 

There are 20 amino acids that can form proteins and four different nucleotides in a chain of mRNA. As a result, three nucleotide bases (triplets) are needed to codify on amino acid.

DNA and mRNA have triplets of bases known as codons. There are 64 different codons that can codify 61 amino acids. Of the remaining three, one is always responsible for initiating the translation and the other two are in charge of finishing the protein synthesis.

It was between 1955 and 1966 that the genetic code was deciphered. Severo Ochoa and his collaborators were able to isolate an enzyme capable of synthesising RNA. 3.4.1. Characteristics of the genetic code

1. Characteristics of the genetic code

The genetic code has a set of characteristics that are common to all living things:

• It is always organised into triplets (codons). Each codon determines an amino acid. 
• It is degenerated. There are more possible triplets (64) than amino acids (20), whichmeans that more than one triplet of bases can codify a particular amino acid.
• There are no overlaps, each nucleotide found in nucleic acid belongs to one particula triplet only.
• When reading the code, there are no blank spaces in it. 
• It is a universal code. The same triplets codify the same amino acids in all species.

This last characteristic clearly points to a common origin for all living things on our planet.

We can summarise the characteristics of the genetic code in the following way:

After the code is deciphered, a cable that links sequences of bases to corresponding amino acids is created.