In the process of protein synthesis, what structures and molecules are directly involved?

Proteins are vital substances for any organism. They participate in all metabolic processes of the cell, they are structural components of organs and tissues, they function as signal molecules. In the process of protein synthesis, many enzymes, as well as cell organelles and nucleus, are directly involved.

Stages of protein synthesis: biological chemistry

The mechanism of building a protein molecule is very complex and requires a large number of factors. Peptides consist of several molecules of amino acids, and their number varies in a very large range.

The correct functioning of the protein depends on the conformation of the molecule, as well as on the number of amino acids and their correct sequence in the peptide. Information about this sequence is stored in DNA, and its violation due to mutations and other factors can lead to the exclusion of vital proteins and cell death.

The following stages of protein synthesis in the cell are distinguished:

1. Transcription.

2. Translation.

Stage one: transcription

In the process of protein synthesis, nucleic acid molecules are directly involved. DNA as a repository of all genetic information encodes with the help of its structural nucleotides the sequence of the future peptide. Starting from the start codon (triplet) and ending with the terminal one, the protein information is read to another nucleic acid - RNA. This single-stranded molecule is transported through the pores in the nucleus into the cytoplasm of the cell.

If in eukaryotes the process of transcription is conjugated with the participation of the nucleus, then in prokaryotes its absence simplifies the synthesis of the peptide. RNA, which is formed on a bacterial chromosome, immediately undergoes processing and joins ribosomes.

Enzymes play a crucial role in the formation and synthesis of RNA on the DNA matrix. In the process of protein synthesis, molecules such as transcription factors, or TF, directly participate. This is a series of proteins that facilitate the flow of the process of reading information from deoxyribonucleic acid.

Stage Two: Broadcasting

When RNA enters the cell cytoplasm from the nucleus, information about the composition of the peptide should be read by special structures. In the process of protein synthesis, ribosomes are directly involved - nemembrannye, small in diameter structures, consisting of two subunits: large and small. RNA is placed between these subunits, after which the reading of information begins.

The codon behind the codon is the construction of a long protein molecule, like a rifle. This is explained as follows: in the inter-ribosomal space, only two codons are placed immediately. When one of them was read, the amino acid is attached to the peptide and, in the form of a tail, falls out of the ribosome through a special opening. This happens the way the cartridge collapses from the gun after the shot.

In the process of protein synthesis, the IF group proteins, or initiation factors, directly participate. With their help, the synthesis of the polypeptide begins from the start codon, which in the vast majority of cases is methionine.

It is worth mentioning that amino acids are supplied to the ribosomes by special vectors called tRNAs, or transport RNAs. These molecules have the form of a clover leaf, at the end of which an amino acid is added, as well as ATP and a special protein - aminoacyl-tRNA synthetase. The whole complex together allows energy to deliver the structural component of the protein to the ribosome and to attach it with the help of a peptide bond.

What are nucleotides?

Nucleic acids are a group of organic compounds that are polymers. They consist of purine (adenine, guanine) and pyrimidine (thymine, cytosine, uracil) bases. The sequence of these nucleotides determines information that is stored in DNA or RNA. This information is read on the ribosomes with the formation of proteins, and for simplicity of the task, the nucleotides are broken down into triplets. Each triplet encodes its amino acid, which delivers tRNA to the ribosomes.

Synthesis of mitochondrial proteins

Mitochondria and plastids have a distinctive feature - they have their own ring DNA, similar to the bacterial chromosome of bacteria. With the help of this nucleic acid, organelles can autonomously work, synthesizing most of their structural proteins.

However, mitochondrial DNA does not store information about factor proteins that are necessary for the process of transcription and translation. These peptides are assembled on the ribosomes, using RNA not the mitochondria, but the nuclei. Therefore, the two-membrane structures are not completely autonomous.

How did the mitochondria and plastids recover their own DNA? It is assumed that these organelles are descendants of bacteria. They lost their independence inside the cell, but they brought with them a ring nucleic acid. This suggests the similarity of DNA mitochondria with a similar molecule of prokaryotes.

Conclusion

All stages of protein synthesis are interrelated, and their task is to build peptide molecules with information stored in nucleic acids. The immediate participants in the process are such structures as the nucleus and ribosomes, as well as some specialized proteins.

In prokaryotes the process of peptide synthesis proceeds much faster because they lack a nucleus. RNA, which is transcribed on the matrix of bacterial DNA, immediately joins the ribosomes, after which simultaneous translation also takes place.