Биосинтез белка

Protein biosynthesis is a multistage process of protein formation of molecules ( polymers) from amino acids (monomers), which is divided into several stages.

Information about the primary structure of the protein is encoded in the DNA molecule in the form of triplets (codons)

Triplet (codon) - a site of three nucleotides in a DNA molecule

One triplet of DNA molecule encodes one amino acid of protein molecule:

1 triplet= 1 amino acid

Gene - a part of the DNA molecule in which information about the structure of one protein is encoded: 1gen= 1 protein

Genetic code-a system of recording genetic information in the DNA molecule about the structure of the protein molecule

Genetic information is recorded only in one (codogenic) DNA chain

The stages of protein biosynthesis

Transcription – "cheating") is the process of reading information about the primary structure of a protein from a DNA molecule by an I-RNA molecule (synthesis of an I-RNA molecule based on a DNA molecule)

Translation-translation of nucleotide sequence from I-RNA to amino acid sequence and Assembly of protein molecule on ribosomes. T-RNA molecules, all kinds of RNA, ribosomes, amino acids take part in the broadcast. There are three stages in protein biosynthesis: initiation, elongation and termination.

Initiation: the first stage is formed by the FCR (functional center of the ribosome), consisting of two codons (6 nucleotides), mRNA and two subunits of ribosomes. First, only a small subunit of the ribosome sits on mRNA. The FCR has two sites: "A" - amino acid, where there is recognition of the brought tRNA amino acid. Joining the amino acid to the peptide chain is in the " P " - peptide phase. The first tRNA brings the amino acid to the" P " phase. Factors of initiation work, and a large subunit of the ribosome is built.

Elongation: comes the second tRNA with the second amino acid and embedded in the " a " area. The enzyme of a large subunit of the ribosome transfers amino acid 1 to amino acid 2 and promotes the formation of a covalent peptide bond between them. Ribosome with high energy is shifted by 1 step on mRNA, the shift is on the frame of one triplet and tRNA + protein system is in the" P "area, and" A " area remains free and ready to receive tRNA with amino acid 3. The process continues until the mRNA information is read and translated from the three-letter language of nucleic acids into the twenty-letter language of proteins. The rate of Assembly of one protein molecule consisting of 200-300 amino acids is 102 minutes (1 step - 0.2 seconds).

Termination: when the ribosome reaches one of the meaningless triplets, special termination factors recognize these "stop signals" and the protein of the synthesized system disintegrates into component parts: protein, ribosome, mRNA.