To study the processes occurring in the body, you need to know what is happening at the cellular level. Where proteins play an important role. It is necessary to study not only their functions, but also the process of creation. Therefore, it is important to explain protein biosynthesis concisely and clearly. Grade 9 is the best fit for this. It is at this stage that students have enough knowledge to understand the topic.
Proteins - what is it and what are they for
These macromolecular 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 vary from a few hundred to thousands.
Proteins perform many functions in the cell. Their role is also great at higher levels of organization: tissues and organs largely depend on the correct functioning of various proteins.
For example, all hormones are of protein origin. But it is these substances that control all processes in the body.
Hemoglobin is also a protein, it consists of four chains, which are in the centerlinked by an iron atom. This structure allows red blood cells to carry oxygen.
Recall that all membranes contain proteins. They are necessary for the transport of substances through the cell membrane.
There are many more functions of protein molecules that they perform clearly and unquestioningly. These amazing compounds are very diverse not only in their roles in the cell, but also in structure.
Where synthesis takes place
The ribosome is the organelle in which the main part of the process called "protein biosynthesis" takes place. Grade 9 in different schools differs in the curriculum of studying biology, but many teachers give material on organelles in advance, before studying translation.
Therefore, it will be easy for students to remember the material covered and consolidate it. You should be aware that only one polypeptide chain can be created on one organelle at a time. 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 EPS is called rough. The benefit of such “collaboration” is obvious: immediately after synthesis, the protein enters the transport channel and can be sent to its destination without delay.
But if we take into account the very beginning, namely the reading of information from DNA, then we can say that protein biosynthesis in a living cell begins in the nucleus. This is where messenger RNA is synthesized.which contains the genetic code.
Required materials - amino acids, synthesis site - ribosome
It seems that it is difficult to explain how protein biosynthesis proceeds, briefly and clearly, a process diagram and numerous drawings are simply necessary. They will help convey all the information, as well as students will be able to remember it more easily.
First of all, the synthesis requires "building material" - amino acids. Some of them are produced by the body. Others can only be obtained from food, they are called indispensable.
The total number of amino acids is twenty, but due to the huge number of options in which they can be arranged in a long chain, 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 which structure the resulting chain will “fold”, whether it will form a quaternary structure with other chains, and what properties the resulting macromolecule will have.
The process of protein biosynthesis cannot proceed simply in the cytoplasm, it needs a ribosome. This organelle consists of two subunits - large and small. At rest, they are separated, but as soon as synthesis begins, they immediately connect and begin to work.
So different and important ribonucleic acids
In order to bring an amino acid to the ribosome, you need a special RNA called transport. Forits abbreviations stand for tRNA. This single-stranded cloverleaf molecule is able to attach a single amino acid to its free end and ferry it to the site of protein synthesis.
Another RNA involved in protein synthesis is called matrix (information). It carries an equally important component of synthesis - a code that clearly states when which amino acid to chain to the resulting protein chain.
This molecule has a single-stranded structure, consists of nucleotides, just like DNA. There are some differences in the primary structure of these nucleic acids, which you can read about in the comparative article on RNA and DNA.
Information about the composition of the protein mRNA receives from the main custodian of the genetic code - DNA. The process of reading deoxyribonucleic acid and synthesizing mRNA is called transcription.
It occurs in the nucleus, from where the resulting mRNA is sent to the ribosome. The DNA itself does not leave the nucleus, its task is only to preserve the genetic code and transfer it to the daughter cell during division.
Summary table of the main participants of the broadcast
In order to describe protein biosynthesis concisely 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.
| What is needed for synthesis | What role does |
| Amino acids | Serve as a building block for the protein chain |
| Ribosome | Arebroadcast location |
| tRNA | Transports amino acids to ribosomes |
| mRNA | Delivers information about the sequence of amino acids in a protein to the site of synthesis |
The very same 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 protein biosynthesis to everyone who wants it in a short and understandable way.
Initiation - the beginning of the process
This is the initial stage of translation, in which the small subunit of the ribosome fuses with the very first tRNA. This ribonucleic acid carries the amino acid methionine. Translation always begins with this amino acid, since the start codon is AUG, which encodes this first monomer in the protein chain.
In order for the ribosome to recognize the start codon and not start synthesis from the middle of the gene, where the AUG sequence can also be, a special nucleotide sequence is located around the start codon. It is by them that the ribosome recognizes the place where its small subunit should sit.
After the formation of the complex with mRNA, the initiation stage ends. And the main stage of the broadcast begins.
Elongation is the middle of synthesis
At this stage, there is a gradual increase in the protein chain. The duration of elongation depends on the number of amino acids in the protein.
First of all to smallthe larger subunit of the ribosome is attached. And the initial t-RNA is in it entirely. Outside, only methionine remains. Next, a second t-RNA carrying another amino acid enters the large subunit.
If the second codon on the mRNA matches the anticodon at the top of the cloverleaf, the second amino acid is attached to the first via a peptide bond.
After that, the ribosome moves along the m-RNA exactly three nucleotides (one codon), the first t-RNA detaches methionine from itself and separates from the complex. In its place is a second t-RNA, at the end of which there are already two amino acids.
Then the third t-RNA enters the large subunit and the process repeats. It will continue until the ribosome hits a codon in the mRNA that signals the end of translation.
Termination
This is the last step, some may find it quite cruel. All the molecules and organelles that worked so well together to create the polypeptide chain stop as soon as the ribosome hits the terminal codon.
It doesn't code for any amino acid, so whatever tRNA goes into the large subunit will all be rejected due to mismatch. This is where termination factors come into play, which separate the finished protein from the ribosome.
The organelle itself can either split into two subunits or continue down the mRNA in search of a new start codon. One mRNA can have several ribosomes at once. Each of them is at its own stage.translations. The newly created protein is provided with markers, with the help of which its destination will be clear to everyone. And by 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. You can read more about the functions of protein molecules in an article on this topic.
How to learn more about streaming
This article describes protein biosynthesis in a living cell. Of course, if you study the subject more deeply, it will take many pages to explain the process in all details. But the above material should be enough for a general idea. Video materials in which scientists have simulated all stages of translation can be very useful for understanding. Some of them have been translated into Russian and can serve as a great guide for students or just 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 functions of proteins.
