For understanding of the processes happening in an organism it is important to know what occurs at the cellular level. The major part is assigned proteinaceous to connections. Both functions, and creation process matter.
High-molecular connections are important in activity of any organisms. Polymers are made of a set of similar particles. Their number varies from hundreds to several thousand. In cages many functions are allocated for proteins. Both bodies, and fabrics depend on correctness of work of formations in the main degree.
Process components
Origin of all hormones – proteinaceous. Namely hormones are responsible for control of all processes which are taking place in an organism. Also protein is hemoglobin, necessary for normal health.
It consists of four chains connected in the center by atom of iron. The structure provides to a design a possibility of transfer of oxygen with erythrocytes.
Proteins are a part of all types of membranes. Molecules of protein solve also other important problems. In the variety the surprising connections differ with both the building, and roles. Ribosomes are especially important.
The main process, protein biosynthesis, takes place in it. The organella at the same time creates the only chain of polypeptides. It is not enough for satisfaction of requirement of all cages. Therefore there is a lot of ribosomes.
Quite often they are merged into rough endoplasmic network (EPS). Benefit both parties from similar cooperation. Directly after synthesis of squirrels it appears in the transport channel. Without delays it goes to the destination.
If to adopt process of information reading from DNA for an important part of the procedure, in living cells the process of biosynthesizing begins in a kernel. There is a synthesizing of the matrix RNA containing the genetic code.
So the sequence of arrangement in a molecule of nucleotides defining the sequence in a proteinaceous molecule of amino acids is called. Everyone has own codon from three nucleotides.
Amino acids and RNA
Synthesis requires construction material. Egor a part is assigned to amino acids. Some of them are developed by an organism, others arrive only with food. They are called irreplaceable.
In total twenty amino acids are known. However they are divided into such quantity of versions that can be located in the longest chain with the diverse proteinaceous molecules.
All acids are among themselves similar in structure. However they differ with radicals. It thanks to their properties each amino-acid chain develops in a certain structure, finds ability to create quarternary structure with other chains, the received macromolecule receives the set properties.
Proteinaceous biosynthesis is impossible in usual course in cytoplasm. Three components are necessary for normal functioning: kernel, cytoplasm and ribosomes. The ribosome is obligatory. The organella includes big and small subunits. So far both at rest, they are separated. At the beginning of synthesis there is an instant connection and working process is started.
Code and gene
Safely to deliver amino acid to a ribosome, transport RNA is necessary (t-RNK). The one-chain molecule looks as a clover leaf. By its free end one amino acid fastens and it is transported thus to the place of proteinaceous synthesis.
The following RNA obligatory for process, is matrix or information (m-RNK). In it especially important component – the code. In it it is registered what amino acid and when needs to be hooked to the formed proteinaceous chain.
The molecule is made by nucleotides as DNA, has the one-chain building. On structure the nucleinic connections in primary structure differ. Data on proteinaceous structure in m-RNK, arrives from DNA, the main keeper of the genetic code.
The procedure of reading of DNA and synthesizing m-RNK call a transcription, that is copying. At the same time the procedure is started not on all extent of DNA, and only on corresponding to a certain gene its small site.
Call a gene the site of DNA with a certain favor of nucleotides, responsible for synthesis of one chain of polypeptides. There is a process in a kernel. From there formed again m-RNK goes to a ribosome.
Procedure of synthesis
DNA does not leave a kernel. It keeps the code, transferring it to a daughter cell in the course of division. It is simpler to present the main initial components in the table.
All process of receiving a chain of protein consists of three stages:
- initiation;
- elongation;
On the first step information on proteinaceous structure which is written down by sequence of nucleotides is transformed to the amino-acid sequence and synthesis begins.
Initiation
The initial period represents connection of a small ribosomal subunit with an initial t-RNK. In ribonucleic acid the amino acid called methionine is concluded. The procedure of broadcasting begins with it in all cases.
As the starting codon AUG acts. He is responsible for coding of the first monomer of a chain. That the ribosome could distinguish a starting codon and did not start synthesis from the middle of a gene where there can also be own sequence of AUG, around an initial codon the special nukleotidovy sequence is located.
On it the ribosome finds the place where its small subunit has to be established. After connection with m-RNK the stage of initiation comes to the end. Process turns into elongation.
Elongation
At an average stage the proteinaceous chain begins to be increased gradually. Duration of the procedure is defined by number in protein of amino acids. At an average stage at once big is connected to a small ribosomal subunit.
By it it is completely absorbed initial t-RNK. At the same time outside there is a methionine. Bearing new acid t-RNK number two comes into a big subunit. At coincidence of the following codon on m-RNK with an anti-codon at top of "a leaf of a clover" the connection to the first new amino acid by means of peptide communication begins.
The ribosome or only on one codon moves to only three nucleotides on m-RNK. Starting t-RNK undocks from methionine, it otmezhevyvatsya from an educated complex. Its place is taken by the second t-RNK. On its end two amino acids already fasten.
In a big subunit the third passes t-RNK and all procedure repeats again. Process lasts until emergence of a codon in m-RNK, reporting about completion of broadcasting.
Termination
The final stage looks rather strictly. Work of the organellas with molecules which are amicably occupied with creation of a chain of polypeptides is interrupted by ribosomal arrival on a terminal codon. He rejects everything t-RNK as he does not support coding of any of amino acids.
His Zakhozhdeniye in a big subunit is impossible. The separation of protein from a ribosome begins. The organella at this stage or breaks up to couple of subunits, or continues the movement on m-RNK, searching for a new starting codon.
One m-RNK may contain in one stage several ribosomes. Everyone has own transmitting stage. Just received protein is marked to define the place of its appointment. It is transported to the addressee on EPS. Synthesis of one proteinaceous molecule happens in a minute or two.
Understanding of the task which is carried out by biosynthesis requires studying functions of this procedure. The main thing is defined by the amino-acid sequence in a chain. A certain favor of codons is responsible for their sequence.
Their properties also set secondariness, a tretichnost or a chetvertichnost of proteinaceous structure and their performance in a cage of certain tasks.