Genetic Code

What is Genetic Code?

The genetic code is the set of rules that determines how the information encoded in genetic material (DNA or RNA) is translated into the sequence of amino acids in a protein. It represents the correspondence between nucleotide triplets (codons) in the genetic material and specific amino acids in the resulting polypeptide chain during protein synthesis.

Features of Genetic Code

Codons

A codon is a three-nucleotide sequence in DNA or RNA that codes for a specific amino acid or a signal to start or stop protein synthesis. There are 64 possible codons, and each codon specifies one of the 20 amino acids used in protein synthesis.

Amino Acids

Amino acids are the building blocks of proteins. Each codon codes for a specific amino acid, and the sequence of codons determines the sequence of amino acids in a protein.

Start and Stop Codons

The genetic code includes start and stop codons that signal the beginning and end of protein synthesis. The start codon (AUG) codes for the amino acid methionine and also serves as the initiation signal. Stop codons (UAA, UAG, and UGA) signal the termination of translation.

Redundancy and Degeneracy

The genetic code is redundant, meaning that more than one codon can code for the same amino acid. This redundancy is due to the fact that there are 64 possible codons, but only 20 amino acids. It also provides a degree of robustness against errors during DNA replication and transcription. The redundancy is known as degeneracy.

Universal Code

The genetic code is nearly universal across all living organisms. With a few exceptions, the same codons code for the same amino acids in all organisms. This universality is a strong indication of the common ancestry of all life on Earth.

Reading Frame

The genetic code is read in a specific reading frame, which begins with the start codon and proceeds in groups of three nucleotides. Maintaining the correct reading frame is crucial for accurate translation of the genetic information.

Evolution of the Genetic Code

The evolution of the genetic code is a subject of scientific study. The genetic code has likely evolved over time, and researchers investigate the factors influencing its universality and specific codon assignments.