Definition

The genetic code is a set of instructions used by living organisms to translate genetic information stored in their DNA or RNA into proteins. It determines the sequence of amino acids that make up proteins, which are essential for the structure and functioning of cells.

Components of the Genetic Code

The genetic code consists of nucleotide sequences, codons, and amino acids.

Nucleotide Sequences

Nucleotide sequences are specific arrangements of DNA or RNA bases, namely adenine (A), cytosine (C), guanine (G), and thymine (T) in DNA or uracil (U) in RNA. These sequences form the genetic information that is transcribed and translated to produce proteins.

Codons

Codons are sequences of three nucleotides that represent a particular amino acid or a stop signal. There are a total of 64 possible codons, of which 61 code for amino acids and the remaining 3 serve as stop signals to terminate protein synthesis.

Amino Acids

Amino acids are the building blocks of proteins. Each codon corresponds to a specific amino acid that is added to the growing protein chain during translation. There are 20 different amino acids commonly found in proteins.

Features of the Genetic Code

The genetic code displays certain characteristics:

Universality

The genetic code is nearly universal, meaning that it is shared by almost all living organisms, from bacteria to plants to animals. This universality allows genetic information to be transferred across different species through evolution.

Degeneracy

Degeneracy refers to the redundancy of the genetic code, where multiple codons can code for the same amino acid. This redundancy provides robustness in translation and protects against certain genetic mutations that may alter a single codon sequence.

Start and Stop Codons

The genetic code contains specific start codons, such as AUG (adenine-uracil-guanine), which initiate protein synthesis, and stop codons, such as UAA (uracil-adenine-adenine), UAG (uracil-adenine-guanine), and UGA (uracil-guanine-adenine), which signal the termination of protein synthesis.