We know that proteins, essential substances for the functioning of the body, are a set of amino acids that are linked together by peptide bonds. The amino acid sequence of a protein will be determined by the arrangement of nitrogenous bases in an mRNA. This, in turn, will be produced from a DNA molecule. We can say, therefore, that DNA provides the information for the production of proteins.
The genetic code can be defined as the relationship between the cracks (codons) found in mRNA and the amino acids found in a protein. Codons are cracks formed by nitrogenous bases (A, U, C and G).
The four nitrogenous bases can have 64 different combinations, so there are 64 different codons. Of those codons, 61 will encode the 20 different types of amino acids that exist. The other three codons (UAA, UAG and UGA) will be responsible for indicating the places where the synthesis ends, being also called stop codons. They do not encode any amino acids and are not read by tRNA, but rather by proteins called releasing factors.
Note the broken nucleotides and the amino acids they encode
Note that there are only 20 types of amino acids, but 61 different triplets that encode them. This is because the same amino acid can be encoded by different codons. Glycine, for example, is encoded by the GGU, GGC, GGA and GGG cracks. This characteristic makes the genetic code be considered degenerate or redundant.
It is important to highlight that only two amino acids are exclusively encoded by a trip: methionine (AUG) and tryptophan (UGG).
This code is universal, being the same for all species of living beings on the planet. The only exceptions are found in RNA produced by mitochondria from some species.
We can say, therefore, that the genetic code has three important characteristics:
-Specificity: A trip will always encode the same amino acid;
- Universality- All living things use the same genetic code to encode amino acids;
- Redundancy- An amino acid can be encoded by different cracks.
by Vanessa dos Santos
Graduated in Biology
Source: Brazil School - https://brasilescola.uol.com.br/biologia/codigo-genetico.htm
