Ribosome: functions and structure

The ribosome, whose functions will be discussed in this article, is a particle that is located directly inside the cell. The main function of this particle is protein biosynthesis. Basic, but not the only one.

The discoverer of the ribosome is considered to be the biologist George Pallade. His discovery was made in 1953, using an electron microscope in his work.

If we talk about the contribution of Russian scientists in the study of the ribosome, then it is worth highlighting the work of the biochemist Academician AS Spirin.

Appearance of the ribosome and its other features

If you carefully consider the cell in electronic micrographs, you can see small particles located in the cytoplasm. These particles are the ribosomes.

ribosome functions

The name "ribosome" consists of two parts. The first resembles "ribonucleic acid", and the second in translation from the Greek "soma" is the body.

The size of the ribonucleic particles of the cell varies within the range of 15-20 nm, and their number is complete

ly dependent on the process of protein biosynthesis, namely, its intensity. As a rule, ribosomes can be about 5000 pieces, in some cases - up to 90 000. If we talk about the mass of this number of particles, it can sometimes reach up to a quarter of the mass of the cell itself.

The shape of the ribosome is more like a sphere, but it is impossible to state this fact unambiguously. But the function of the ribosomes in the cell is associated with protein biosynthesis, and this is a confirmed fact.

In their chemical nature, these particles belong to the nucleoproteins( a combination of nucleic acids with protein), which consist of ribonucleic acid.

Prokaryotic type

There are two types of ribosomes, the structure and functions of which differ slightly from each other.

The first type is characteristic for cells of bacteria and green algae, that is prokaryotic organisms. Its name is the 70S ribosome, the functions it performs are the same. The number in the name means the sedimentation coefficient( a quantity that determines the size and shape of macromolecules, as well as the deposition rate of a specific microparticle, in this case a ribosome, in a sufficiently strong gravitational field).For this type, it is 70 Svedberg units. These ribosomes consist of two unequal particles: 30S and 50S.The first component contains one protein molecule, in the second - two RNA molecules. The basic function that the protein molecules that make up the ribosome perform is the structural function.

ribosomes structure and function

Eukaryotic type

The second type of ribosome was found in eukaryotic cells( plant or animal organisms in which a clearly expressed nucleus is present in the cells).The name of this subparticle is 80S.Ribosomes, whose functions consist in the synthesis of proteins of this class, consist of equal parts of RNA and protein. But all the same two unequal subunits are in them( 60S and 40S).

Ribosomes: structure and functions of the

The ribosome consists of two unequal subunits.

The large subparticle, in turn, consists of:

  • of one molecule of ribosomal RNA, which is highly polymeric;
  • one molecule of RNA, which is low-polymer;
  • some number of protein molecules, as a rule, they are about three dozen.

As for the smaller subparticle, it's a bit simpler here. It consists of:

  • molecule of high-polymeric RNA;
  • several tens of protein molecules, usually about 40 pieces( molecules with different in structure and form).

ribosomes perform the function

A molecule of high-polymeric RNA is necessary in order to connect all the proteins present in one complete ribonucleoprotein component of the cell.

In the process of performing its basic function, that is, during protein synthesis, the ribosome performs a number of additional ones:

  1. Bundle, as well as retention of all components of the so-called protein-synthesizing system. It is customary to call this function information, or matrix. The ribosome distributes these functions between its two subparticles, each of which fulfills its specific task in this process.
  2. Ribosomes perform a catalytic function, which consists in the formation of a special peptide bond( an amide bond that occurs both in the formation of proteins and in the occurrence of peptides).This also includes the hydrolysis of GTP( a substrate for the synthesis of RNA).A large subunit of the ribosome responds to this function. It is in it are special areas in which the process of synthesis of peptide bonding takes place, as well as the center necessary for hydrolysis of GTP.In addition, it is the large subunit of the ribosome that, during the biosynthesis of the protein, retains a chain that gradually grows.
  3. Performs the ribosome functions of mechanical movement of substrates, to which the mRNA and tRNA belong. In other words, they are responsible for translocation.

ribosome function in a cell

As a conclusion

Literally, each of the subunits of a ribosome, both large and small, can manifest to some extent those functions that are directly associated with it, separately from its "neighbor".However, only the ribosome in its entirety can perform the function of translocation.

It can be safely said that there is a clear separation of functions between particles of the ribosome. A small part is responsible for performing the reception, as well as deciphering the genetic information. But a large particle takes a direct part in transliteration.

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