Biosynthesis of protein: brief and understandable. Biosynthesis of protein in a living cell

To study the processes taking place in the body, you need to know what is happening at the cellular level. And protein compounds play an important role there. It is necessary to study not only their functions, but also the process of creation. Therefore, it is important to explain the biosynthesis of the protein briefly and clearly. 9 grade for this is the best way. It is at this stage that students have sufficient knowledge to understand this topic.

Proteins - what is it and what are they for?

These high-molecular compounds play a huge role in the life of any organism. Proteins are polymers, that is, they consist of many similar "pieces". Their number can range from a few hundred to thousands.

In a cell, proteins perform many functions. Their role is also great at higher levels of organization: tissues and organs largely depend on the proper functioning of various proteins.

For example, all hormones are of protein origin. But these substances control all the processes in the body.

Hemoglobin - also a protein, it consists of four chains, which in the center are connected by an iron atom. Such a structure provides an opportunity to carry oxygen by red blood cells. Recall that all membranes have proteins in their composition. They are necessary for the transport of substances through the cell membrane.

There are many more functions of protein molecules, which they perform clearly and unquestioningly. These amazing compounds are very diverse not only in their roles in the cell, but also in structure.

Where does the synthesis occur

The ribosome is an organelle in which the main part of the process, called "protein biosynthesis", passes. Grade 9 is different in different schools according to the biology curriculum, but many teachers give material on organelles in advance, before studying the broadcast.

Therefore, it will not be difficult for students to recall the material they have covered and to fix it. One should know that only one polypeptide chain can be created at the same organelle simultaneously. This is not enough to satisfy all the needs of the cell. Therefore, there are a lot of ribosomes, and most often they are combined with the endoplasmic reticulum. Such an EPS is called a rough one. The benefit of such a "cooperation" is obvious: the protein immediately after synthesis is in the transport channel and can go to the destination without delay.

But if we take into account the very beginning, namely the reading of information from DNA, then we can say that the biosynthesis of the protein in a living cell begins even in the nucleus. It is there that the matrix RNA is synthesized, which contains the genetic code.

The required materials are amino acids, the site of synthesis is the ribosome

It seems that it is difficult to explain how the protein biosynthesis proceeds, briefly and clearly, the process scheme and numerous drawings are simply necessary. They will help to convey all the information, and also students will be able to easily remember it.

First of all, the synthesis requires a "building material" - amino acids. Some of them are produced by the body. Others can only be obtained with food, they are called irreplaceable. The total number of amino acids is twenty, but due to the huge number of variants in which they can be located in a long chain, the protein molecules are very diverse. These acids are similar in structure, but differ in radicals.

It is the properties of these parts of each amino acid that determine what structure the chain turns into, whether it will form a quaternary structure with other chains, and what properties the resulting macromolecule will possess. The process of protein biosynthesis can not proceed simply in the cytoplasm, for it a ribosome is needed. This organelle consists of two subunits - large and small. In a state of rest, they are disunited, but as soon as synthesis begins, they immediately connect and begin to work.

Such different and important ribonucleic acids

In order to bring the amino acid to the ribosome, you need a special RNA, called transport. To reduce it, t-RNA is indicated. This single-stranded molecule in the form of a clover leaf is capable of attaching one amino acid to its free end and transferring it to the site of protein synthesis.

Another RNA involved in protein synthesis is called the matrix (information). It carries in itself an equally important component of synthesis - a code in which it is clearly prescribed, when which amino acid to cling to the forming chain of protein.

This molecule has a single-stranded structure, consists of nucleotides, as well as DNA. There are some differences in the primary structure of these nucleic acids, which you can read about in a comparative article on RNA and DNA.

Information on the protein composition of mRNA is obtained from the main custodian of the genetic code - DNA. The process of reading deoxyribonucleic acid and the synthesis of m-RNA is called transcription.

It occurs in the nucleus, from where the resulting mRNA is sent to the ribosome. The DNA itself does not come out of the kernel, its task is only to preserve the genetic code and transfer it to the daughter cell during division.

Summary table of main broadcast participants

In order to describe the biosynthesis of the protein briefly and clearly, a table is simply necessary. In it, we will write down all the components and their role in this process, which is called translation.

The very process of creating a protein chain is divided into three stages. Let's look at each of them in more detail. After that, you can easily explain to everyone who wants protein biosynthesis briefly and clearly.

Initiation - the beginning of the process

This is the initial stage of translation, in which a small subunit of the ribosome binds to the very first t-RNA. This ribonucleic acid carries an amino acid - methionine. Translation always begins with this amino acid, since the starting codon is AUG, which also encodes this first monomer in the protein chain.

In order for the ribosome to recognize the start codon and not start the synthesis from the middle of the gene, where the sequence of AUH may also turn out, a special sequence of nucleotides is located around the initial codon. It is for them that the ribosome recognizes the place on which its small subunit should sit.

After formation of the complex with m-RNA, the initiation stage ends. And the main stage of the broadcast begins.

Elongation is the middle of synthesis

At this stage, a gradual build-up of the protein chain occurs. The duration of elongation depends on the amount of amino acids in the protein.

First of all, a large subunit of the ribosome joins the small subunit. And the initial tRNA is in it entirely. Outside, there is only methionine. Further, a second t-RNA, carrying a different amino acid, enters the large subunit.

If the second codon on mRNA coincides with the anticodon at the top of the clover leaf, the second amino acid is attached to the first by a peptide bond.

After this, the ribosome moves along m-RNA exactly three nucleotides (one codon), the first t-RNA detaches methionine from itself and separates from the complex. In its place is the second t-RNA, at the end of which there are already two amino acids.

Then a third t-RNA enters the large subunit and the process repeats. It will occur until the ribosome encounters the codon in mRNA, which signals the end of the translation.

Termination

This stage is the last, some it may seem very cruel. All molecules and organelles, which worked so smoothly together to create a polypeptide chain, stop as soon as the ribosome hits the terminal codon.

It does not encode any amino acid, so whatever T-RNA enters into the big subunit, they will all be rejected because of inconsistency. Here, the factors of termination come into play, which separate the finished protein from the ribosome.

The organelle itself can either disintegrate into two subunits, or continue its journey through mRNA in search of a new start codon. On one mRNA there can be several ribosomes at once. Each of them is at its own stage of translation. Only the created protein is supplied with markers, through which everyone will understand its destination. And according to EPS it will be sent to where it is needed.

To understand the role of protein biosynthesis, it is necessary to study what functions it can perform. It depends on the sequence of amino acids in the chain. It is their properties that determine the secondary, tertiary, and sometimes quaternary (if it exists) protein structure and its role in the cell. More details about the functions of protein molecules can be found in the article on this topic.

Learn more about casting

This article describes the biosynthesis of protein in a living cell. Of course, if you study the subject deeper, the explanation of the process in all the details will take many pages. But the above material should be sufficient for a general presentation. Video materials in which scientists modeled all the stages of the broadcast can be very useful for understanding. Some of them are translated into Russian and can serve as an excellent guide for students or simply an educational video.

In order to understand the topic better, you should read other articles on related topics. For example, about nucleic acids or about the function of proteins.