genetic code - especially hereditary information encryption using nucleic acid molecules.Based on this information, the encoded genes suitable controlled synthesis of proteins and enzymes in the body, thereby defining metabolism.In turn, the structure of individual proteins and their function determines the location and composition of amino acids - the structural units of the protein molecule.
In the middle of the last century have been identified genes that are separate sections of deoxyribonucleic acid (abbreviated - DNA).Units of nucleotides in DNA molecules to form a double strand characteristic collected in the form of a spiral.
Scientists have found a link between genes and the chemical structure of individual proteins, the essence of which is that the structural order of the amino acids in the protein molecule completely corresponds to the order of nucleotides in a gene.Having established this relationship, the researchers decided to decipher the genetic code, ie,establish laws relevant structural order of nucleotides in DNA and amino acids in proteins.
There are only four types of nucleotides:
1) A - adenine;
2) G - guanine;
3) T - thymidylic;
4) C - cytidylic.
of the protein enters the twenty kinds of essential amino acids.With the deciphering of the genetic code, are having difficulties because of nucleotides is much less than aminoskislot.To solve this problem, it was suggested that the amino acids are encoded by different combinations of three nucleotides (so-called a triplet or codon).
If you count all the possible combinations of the triplets is 64, that is three times more than the amino acids - the excess obtained triplets.
In addition, it was necessary to explain exactly how triplets are located along the gene.So there are three main groups of theories:
1) The triplets follow each other continuously, ieform a continuous code;
2) triplets are arranged with alternating "meaningless" sites, ieforming the so-called "comma" and "paragraph" in the code;
3) triplets may overlap, ieend of the first triplet can form the beginning of the next.
Currently mainly used the theory of the continuity of the code.
Genetic code and its properties
1) triplet code - it consists of arbitrary combinations of three nucleotides, which form the codons.
2) The genetic code is redundant - it is a consequence of his triplet.One amino acid may be encoded by several codons as codons for mathematical calculations, three times more than the amino acids.Several termination codons perform certain functions: some may be "stop signals" that program end production of the amino acid chain, while others may represent the initiation of the read code.
3) The genetic code is unambiguous - each of codons can correspond to only one amino acid.
4) The genetic code has collinear, iethe nucleotide and amino acid sequence clearly correspond to each other.
5) code is recorded continuously and compact, "meaningless" nucleotides are missing.It begins with a specific triplet, which is replaced by the following non-stop codon and ends.
6) The genetic code is universal - any organism genes encode for proteins exactly the same way.It does not depend on the complexity of the organization or system of the body position.
Modern science suggests that the genetic code arises immediately upon the birth of a new organism of bone matter.Random changes and evolutionary processes make possible any options code, ieamino acids may be interchanged in any order.Why in the course of evolution has survived exactly this kind of code, why the code is universal and has a similar structure?The more science learns about the phenomenon of the genetic code, the more there is of new mysteries.
