The several key features of the genetic code are:
1. Commaless Structure:
The genetic code exhibits a commaless arrangement, where triplet codons on m-RNA follow one another seamlessly without gaps. This absence of commas in the sequence is a distinctive feature.
2. Non-ambiguous Nature:
Each codon holds the unique ability to specify a particular amino acid, contributing to the non-ambiguous nature of the genetic code. While most codons correspond to specific amino acids, exceptions like AUG coding for methionine and GUG coding for valine exist. Notably, GUG can also serve as a methionine coder in the absence of AUG.
3. Degenerate Nature:
The genetic code displays degeneracy, with 61 codons responsible for encoding 20 amino acids. This degeneracy arises because some amino acids are represented by multiple codons. For instance, GGG, GGA, GGC, and GGU all code for the amino acid glycine.
4. Polarity and Directionality:
The genetic code is unidirectional, readable only in the 5′-3′ direction on m-RNA. This directional aspect is crucial, and it includes distinctive start and stop signals. The initiation codon is AUG, while UAG, UAA, and UGA function as termination codes, marking the conclusion of the protein synthesis process.
5. Universality:
A noteworthy characteristic of the genetic code is its universality, extending across diverse organisms, from simple bacteria to complex life forms. This universality underscores the fundamental role of the genetic code in the continuity of life processes across different species.