The genetic code is the code our body uses to convert the instructions contained in our DNA the essential materials of life. It is typically discussed using the “codons” found in mRNA, as mRNA is the messenger that carries information from the DNA to the site of protein synthesis.
Everything in our cells is ultimately built based on the genetic code. Our hereditary information – that is, the information that’s passed down from parent to child – is stored in the form of DNA. That DNA is then used to build RNA, proteins, and ultimately cells, tissues, and organs.
Like binary code, DNA uses a chemical language with just a few letters to store information in a very efficient manner. While binary uses only ones and zeroes, DNA has four letters – the four nucleotides Adenine, Cytosine, Guanine, and Thymine/Uracil.
Thymine and Uracil are very similar to each other, except that “Thymine” is slightly more stable and is used in DNA. Uracil is used in RNA, and has all the same properties of Thymine except that it is slightly more prone to mutate.
This doesn’t matter in RNA, since new RNA copies can be produced from DNA at any time, and most RNA molecules are intentionally destroyed by the cell a short time after they’re produced so that the cell does not waste resources producing unneeded proteins from old RNA molecules.
Together, these four letters of A, C, G, and T/U are used to “spell” coded instructions for each amino acid, as well as other instructions like “start transcription” and “stop transcription.”
Instructions for “start,” “stop,” or for a given amino acid are “read” by the cell in three-letter blocks called “codons.” When we talk about “codons,” we usually mean codons in mRNA – the “messenger RNA” that is made by copying the information in DNA.
For that reason, we talk about codons made of RNA, which uses Uracil, instead of the original DNA code which uses Thymine.
Each amino acid is represented in our genetic instructions by one or more codons, as seen below.
Codon table
One of the most remarkable evidences for the common descent of all life on Earth from a single ancestor is the fact that all organisms use the same genetic code to translate DNA into amino acids.
There are a few slight exceptions to be found, but the genetic code is similar enough across organisms that when a gene from a plant or jellyfish is injected into a mammal cell, for example, the mammal cell will read the gene in the same way and build the same product as the original plant or jellyfish!
Explanation:
