Ribosomes are important cells of the cells that are on the surface of the endoplasmic network. The structure of the ribosome is associated with protein synthesis.

Structure

Ribosoma is a non-smiled organella, consisting of two parts - subunits. Ribosomes fall on EPS or in cytoplasm from the nucleoline through the pores of the membrane wall of the kernel.
Depending on the location of the ribosome there are two types:

• related - settle on EPS;
• free - are in the cytoplasm.

Subunits are divided into two types - large and small. Each part consists of a mixture of nucleic acids and protein, i.e. According to the chemical structure of the ribosome is a nucleoproteide.

Fig. 1. The structure of Ribosomes.

The ribosome of the eukaryotic cell includes four types of ribosomal RNA (RRNA) differing in the number of nucleotides:

• 18s - 1900 nucleotides;
• 5S - 120 nucleotides;
• 5.8S - 160 nucleotides;
• 28S - 4800 nucleotides.

18S-RRNA and 30-35 proteins make up a small subunit, the remaining ribonucleic acids and 45-50 proteins are part of a large subunit. A large subunit of prokaryotic includes two types of RNA, and small one.

In the nucleoline subunits are synthesized separately. They are assembled in a place in a single ribosoy only for work - protein synthesis, which occurs on a matrix RNA. Subunits are wrapped with mRNA, gathering in complexes, which are called polysomas or polyribosomes.

Top 4 Articleswho read with this

Fig. 2. Polisomas and mRNA.

According to the structure of the ribosome of the animal cell, no different from the plant cell. However, plant cells contain significantly less ribosomes, because Chloroplasts play the main role in metabolism.

Functions

The main function of organide - protein synthesis.
The protein biosynthesis includes several components:

• mRNA;
• rRNA;
• polypeptide;
• 20 amino acids;
• Gtf (guanosineryphosphate) as a source of energy;
• ribosomal proteins;
• protein factors regulating process.

Biosynthesis occurs in two stages:

• transcription - reading and copying information from DNA, MRNA formation;
• broadcast - protein synthesis on ribosomes using transport RNA (TRNA).

Matrix RNA - cast, template with DNA, by which the ribosome is synthesized by the protein. The shortest ribonucleic acid - transport RNA - transfers amino acids to the site of protein synthesis, building a polypeptide chain. At the same time, for each amino acid there is its own TRNA.

The transmission process includes three phases:

• initiation - ribosome is attached to the beginning of mRNA;
• elongation - proper protein synthesis, the formation of a polypeptide chain;
• termination is the release of the synthesized chain from the ribosome.

The elongation occurs pretty quickly. In a second, the polypeptide chain increases about 20 amino acids. The release of the chain contributes to stop codons (UAA, UAG, UGA) on mRNA. These codons do not encode amino acids, and the synthesis ends with them.

Fig. 3. Synthesis protein on ribosomes.

The ribosome includes 10% of the entire cell protein and 80% of cell RNA.

What does this organella look like? She looks like a phone with a tube. (Fig. 6) The ribosome of eukaryotes and prokaryotes consists of two parts, one of which is more, the other is less. But these two components do not connect together when it is in a calm state. This happens only when the ribosome of the cell directly begins to perform its functions. Ribosome also has an information RNA and transport RNA in its composition. These substances are necessary in order to record information about the necessary cells of proteins. Ribosoma has no own membrane. Her subunits (so called two half half) are not protected.

Figure 6. Appearance of ribosomes.

The big subparticle, in turn, consists of:

• · One ribosomal RNA molecule, which is high polymer;
• · One RNA molecule, which is low polymer;
• · Some number of protein molecules, as a rule, are about three dozen.

As for the smaller sub-obscurity, it is a little simpler. (Fig. 7) It includes:

• · Molecule of high polimerous RNA;
• · Several dozen protein molecules, as a rule, about 40 pieces (molecules are diverse in structure and form).

Figure 7. The smaller sub-displete of the ribosomes.

The molecule of high-polimerous RNA is necessary in order for all present proteins to combine into one holistic ribonucleoprote-shaped cell component.

Ribosoma functions

What functions performs this organid in the cell? What the ribosome is responsible for which is protein synthesis. It occurs on the basis of information that is recorded on the so-called matrix RNA (ribonucleic acid). The ribosome combines its two subunits only for the synthesis of protein - a process called broadcast. (Fig. 8) During this procedure, the synthesized polypeptide chain is between two ribosome subunits.

Figure 8. Translation process.

In the process of performing the main function, that is, during the synthesis of protein, the ribosoma performs a number of additional:

• · Bunch, as well as the retention of all components of the so-called whiteoxifying system. It is customary to call this feature of information, or matrix. The ribosome of the functions of these distributes between the two sub-interpreters, each of which performs its specific task in this process.
• · Ribosomes perform a catalytic function, which lies in the formation of a special peptide bond (an amide bond, which occurs both in the formation of proteins and in the occurrence of peptides). This can also include hydrolysis GTF (substrate for RNA synthesis). For the execution of this function, a large ribosome subunit is responsible. It is in it that there are special areas in which the process of peptide synthesis occurs, as well as the center necessary for hydrolysis GTF. In addition, it is a large ribosome subunit during the protein biosynthesis holds a chain that gradually grows.
• · Performs a ribosome of the function of mechanical movement of substrates, which includes IRNA and TRNA. In other words, they are responsible for translocation.

Figure 9. Synthesis of protein.

How does the formation of proteins? (Fig. 9, 10, 11) protein biosynthesis occurs in several stages. The first of these is the activation of amino acids. There are twenty there, there are twenty, when combining them with different methods, you can get billions of different proteins. Throughout this stage, aminoalitz-T-RNA is formed.

Figure 10. Protein synthesis (photo).

This procedure is impossible without the participation of ATP (adenosineryphosphoric acid). Also for the implementation of this process requires magnesium cations. The second stage is the initiation of the polypeptide chain, or the process of combining two ribosome subunits and supply to it necessary amino acids. In this process, magnesium and gtf ions also take part (guanosintrifhosphate). The third stage is called elongation. This is directly the synthesis of the polypeptide chain. It occurs using the broadcast method. Termination - the next stage is the process of decaying ribosomes into separate subunits and gradual cessation of the synthesis of the polypeptide chain. Next is the last stage - the fifth is processing. At this stage, complex structures that are already ready proteins are formed from a simple chain of amino acids. Specific enzymes are involved in this process, as well as cofactors.

Figure 11. Synthesis of protein (scheme).

Since the ribosome is responsible for protein synthesis, then let's consider in more detail their structure. It happens primary, secondary, tertiary and quaternary. Primary protein structure is a specific sequence in which amino acids forming this organic compound are located. The secondary protein structure is an alpha spiral and beta folds formed from polypeptide chains. The tertiary protein structure provides a certain combination of alpha spirals and beta folds. The quaternary structure is the formation of a single macromolecular education. (Fig. 12) That is, combinations of alpha spirals and beta structures form globular or fibrils. On this principle, two types of proteins can be distinguished - fibrillary and globular.

The first includes such as actin and myosin, of which muscles are formed. Examples of the second can serve hemoglobin, immunoglobulin and others. Fibrillar proteins resemble a thread, fiber. Globular more similar to the ball of woven alpha spirals and beta folds. What is denaturation? Every one probably heard this word.

Figure 12. Quaternary protein structure.

ribosome cell protein genetic

Denaturation is the process of destruction of the protein structure - first quaternary, then tertiary, and after - and secondary. In some cases, the liquidation of the primary structure of the protein occurs. This process may occur as a result of the impact on this organic substance of high temperature. Thus, protein denaturation can be observed during cooking chicken eggs. In most cases, this process is irreversible. So, at a temperature above forty-two degrees, denaturation of hemoglobin begins, so the strong hyperthermia is dangerous for life. Denaturation of proteins to separate nucleic acids can be observed in the process of digestion, when the body splits complex with the help of enzymes organic compounds on simpler.

For the first time, the ribosomes were found in an animal cage in 1955. In the same year, data were obtained that they perform important functions in the exchange of substances - are protein biosynthesis centers. Ribosomes contribute to the implementation of hereditary cell information and ensure the uniqueness of each type of organisms due to the formation of proteins specific for it.

Localization

Ribosomes are present in all types of cells. They are formed in the kernel, then come out of it and posted in:

• cytoplasm;
• mitochondria;
• plastids;
• on the membranes of the endoplasmic network (EPS).

Fig. 1. Ribosomes on membranes with rough EPS.

Structure

The ribosome has dimensions of about 25-30 nm and consists of two unequal particles, called large and small subunits.

Fig. 2. The structure of the ribosome.

Each subunit in the protein synthesis process performs its function. By chemical composition Ribosomes are a complex of proteins and RNA, and it is RNA that determines their properties.

Synthesis protein

The protein biosynthesis process is extremely complicated and energy intensity.
They are involved in it:

• regulatory proteins;
• proteins catalysts;
• ATP and GTF, as energy sources;
• transport and information RNA molecules;
• magnesium ions.

Ribosomes are centers and organizers of a whiteoxifying system, which is capable of working also outside the cell.

Transcription

Information about the structure of the protein is in the gene.

Top 4 Articleswho read with this

In the process of transcription in the core core, a copy of the gene is formed in the form of information RNA (and-RNA). Information in this case is a certain sequence of nucleotides, compound parts and-RNA.

The nucleotide sequence and-RNA encodes the nucleotide DNA sequence (the gene is a DNA section).

Broadcast

After the RNA comes out of the kernel to the cytoplasm, the ribosome is joined to it, thereby initiating the assembly of the whiteoxynthesive system.

The transmission process is then begins - the synthesis of protein molecule from amino acids, which are delivered to the ribosome by transport RNA (T-RNA).

Fig. 3. Squirrel biosynthesis scheme on ribosome.

After joining each new amino acid, the ribosoma subunits move along a chain and-RNA to one codon. The codon is three nucleotides encoding a certain amino acid.

Total information about the composition of the protein is rewritten twice, first with DNA on and-RNA, then with and-RNA to the protein itself. Information in protein is a sequence of amino acids, and in DNA and and-RNA - a sequence of nucleotides.

In the process of protein biosynthesis, the following functions of ribosomes are carried out:

• a bunch and retention of the components of the whiteoxitheating system;
• catalysis of reactions leading to the formation of peptide bonds;
• catalysis hydrolysis GTF;
• mechanical movement along the chain and RNA.

Differences in the structure and performed functions of ribosomal subunits are presented in the table.

The function of moving the ribosome software and RNA is carried out together with two subunits.

What did we know?

We found out what function is performed in the ribosome cell. They are the main part of the whiteoxitheating system. On ribosomes, protein molecules assemble. The proteins that are part of the ribosoma themselves regulate and catalyze protein synthesis processes.

Test on the topic

Report assessment

average rating: 4.1. Total ratings obtained: 62.

The structure of ribosomes. Ribosomes are found in the cells of all organisms. This microscopic rounded shape calves with a diameter of 15-20 nm. Each ribosome consists of two unequal particles, small and large. In one cell contains many thousands of ribosomes, they are located either on the membranes of the granular endoplasmic network, or are freely lying in the cytoplasm. The ribosoma includes proteins and RNA. Ribosoma function is a protein synthesis. Protein synthesis is a complex process that is carried out not with a single ribosome, but a whole group comprising up to several tens of combined ribosomes. Such a group of ribosoma is called a polis. Synthesized proteins first accumulate in the channels and cavities of the endoplasmic network, and then transported to organoids and sections of the cells where they are consumed. The endoplasmic network and ribosomes located on its membranes are a single apparatus of biosynthesis and transportation of proteins. The chemical composition of the ribosoma in the ribosome of eukaryotic type 4 RRNA molecules and about 100 protein molecules, prokaryotic type - 3 RRNA molecules and about 55 protein molecules. During the biosynthesis, the ribosome protein can "work" by one or unite into complexes - polyribosomes (polisoms). In such complexes, they are connected with each other by the same INK molecule. Procarniotic cells have only 70S-type ribosomes. Eukaryotic cells have ribosomes like 80s-type (rough membranes EPS, cytoplasma) and 70s-type (mitochondria, chloroplasts). The ribosome eukaryotes are formed in the nucleoline. Combining subunits to a whole ribosome occurs in the cytoplasm, as a rule, during the protein biosynthesis.

Ribosoma function: polypeptide chain assembly (protein synthesis).

Free ribosomes, polyribosomes, their connection with other structural components of the cell.

There are single ribosomes and complex ribosomes (polisms). Ribosomes can be located freely in the hyaloplasm and be associated with the membranes of the endoplasmic network. Free ribosomes form proteins mainly on their own cell needs associated with protein synthesis "for export".

53 Intermediate Filaments

(PF) - filamentous structures of special proteins, one of the three main components of the cytoskeleton of eukaryotes cells. It contains both in the cytoplasm and in the kernel of most eukaryotic cells. In contrast to other major elements of the cytoskeleton, the PF in the cytoplasm of cells of different tissues consist of different, although similar in its structure of proteins. The cytoplasmic PF is not all eukaryotes, they are found only in some groups of animals. So, the PF is nematode. Mollusks and vertebrates. But not found in arthropods and iglozzy. Village PF is missing in some cells (for example, oligodendrocytes). IN plant cells PF was not detected. In most animals, PF cells form a "basket" around the kernel, from where they are directed to the periphery of the cells. The PF is especially much in cells subject to mechanical loads: in the epitheliums, where the PF is involved in the combination of cells with each other through the desplaomoms, in the nerve fibers, in the cells of smooth and cross-striped muscle tissue.

Ribosomes are the most important components of cells both prokaryotes and eukaryotes. The structure and functions of ribosomes are associated with protein synthesis in a cell, i.e. the broadcast process.

By chemical composition of ribosomes are ribonucleoproteis, i.e. consist of RNA and proteins. The ribosome includes only one type of RNA - RRNA (ribosomal RNA). However, there are 4 varieties of its molecules.

According to the structure of ribosomes, it is small, rounded form, non-smuggled cell organides. Their amount in different cells varies from thousands of up to several million. Ribosome is not a monolithic structure, it consists of two particles that call big and small subunits.

In eukaryot cells, most ribosomes are attached to the EPS, as a result of which the latter becomes rough.

Most of the RRNA constituting the ribosomes is synthesized in the nucleoline. Yazryshko form certain sections of different chromosomes, containing many copies of genes, on which the precursor of the RRNA molecules is synthesized. After the predecessor synthesis, it is modified and disintegrated by three parts - different RRNA molecules.

One of the four types of rRNA molecules is not synthesized in the nucleoline, but in the kernel on other sections of chromosomes.

In the core, the assembly of individual subunits of ribosomes, which then go to the cytoplasm, where the protein synthesis is combined.

On the structure, both subunits ribosoma are RRNA molecules that take certain tertiary structures (folded) and are inlaid with dozens of different proteins. At the same time, three RRNA molecules include two RRNA molecules (prokaryotic - two), and only one.

The only function of ribosomes is to ensure the possibility of flowing chemical reactions in the biosynthesis of protein in the cell. Matrix RNA, transport RNA, a plurality of protein factors in the ribosome occupy certain provisions, which makes it possible to effectively lent chemical reactions.

When combining subunits in the ribosome, "places" - sites are formed. The ribosome moves on mRNA and "reads" codon for the codon. In one site, TRNA comes with an amino acid attached to it, in the other - the previously arrived TRNA, to which a previously synthesized polypeptide chain is attached. In the ribosome, a peptide connection is formed between the amino acid and polypeptide. As a result, the polypeptide turns out to be on the "new" TRNA, and the "old" leaves Ribosoma. The remaining TRNA is shifted to her place together with its "tail" (polypeptide). The ribosome is shifted by mRNA forward to one triplet, and complementary TRNA and so on to it joins it.

On one mRNA circuit, several ribosomes are moved by each other, forming policy.