To study the processes occurring in the body, you need to know what happens at the cellular level.But there is a crucial role is played by protein compounds.It is necessary to examine not only their function, but also the process of creating.Therefore, it is important to explain the biosynthesis of proteins briefly and clearly.Grade 9 is suitable for this in the best way.At this stage, students possess enough knowledge to understand the topic.
Proteins - what it is and what they need
These macromolecular compounds play an important role in the life of any organism.Proteins are polymers that is composed of a plurality of similar "pieces".Their number may vary from a few hundred to a thousand.
The cell proteins perform a variety of functions.Great is their role, and at higher levels of organization: the tissues and organs is largely dependent on correct operation of the various proteins.
For example, all the hormones are protein origin.But these substances control all processes in the body.
Hemoglobin - also a protein, it is composed of four chains, which are connected near the iron atom.Such a structure allows to transport oxygen eritrotsitami.Napomnim that all membranes are composed of proteins.They are necessary for the transport of substances through the cell membrane.
There are many functions of protein molecules, they perform well and without question.These amazing compounds are very diverse, not only for her roles in the cell, but also in structure.
Where the synthesis
The ribosome is the organelle in which the main part of the process called "protein biosynthesis."9th grade in different schools differs according to the program of studying biology, but many teachers give material of organelles in advance of the study of translation.
Therefore, students will not be difficult to remember the material covered and secure.You should know that at the same time on one organelle can be created only one polypeptide chain.It's not enough to meet all the needs of the cell.Therefore, a lot of ribosomes, and often they are combined with the endoplasmic reticulum.Such XPS called rough.The benefits of such "cooperation" is obvious: as soon as the protein synthesis gets into a transport channel, and can be sent without delay to the destination.
But if you take into account the very beginning, namely the reading of information from DNA, it can be said that the biosynthesis of proteins in living cells begins in the nucleus.It was there that synthesized messenger RNA, which contains the genetic code.
Materials - amino acids, the synthesis of a place - the ribosome
It seems that it is difficult to explain how the protein biosynthesis takes place, brief and clear process diagram and numerous drawings are essential.They will help to bring all the information, as well as students will be able to easily remember it.
First of all, is necessary for the synthesis of "building blocks" - amino acids.Some of them are produced by the body.Others can only be obtained from food, they are called nezamenimymi.Obschee number of amino acids - twenty, but due to the huge number of options in which they can be placed in a long chain protein molecules are very diverse.These acids are similar to each other in structure but different radicals.
precisely the properties of these parts of each amino acid is determined in what structure "minimizes" the resulting chain, whether it will form a quaternary structure with other chains, and what properties will have makromolekula.Protsess the resulting protein biosynthesis can not occur just in the cytoplasm, it requires a ribosome.This organelle is composed of two subunits - large and small.At rest, they are fragmented, but as soon as the fusion, they immediately join and start to work.
Such different and important ribonucleic acid
In order to bring the amino acids to the ribosome, need a special RNA, called transport.To reduce its designated tRNA.This single-stranded molecule in a cloverleaf able to attach a single amino acid to its free end, and forward it to the site of protein synthesis.
Another RNAs involved in protein synthesis, called the matrix (information).It carries the least important component of synthesis - the code, which clearly stipulates that any amino acid cling to the image of the protein chain.
This molecule is a single chain structure consisting of nucleotides as well as DNA.There are some differences in the primary structure of nucleic acids, of which you can read in a comparative article on RNA and DNA.
information on the composition of the protein mRNA receives from the chief custodian of the genetic code - the DNA.The process of reading and synthesis of deoxyribonucleic acid mRNA is called transcription.
It occurs in the nucleus, where the resulting mRNA goes to a ribosome.The very same DNA from the nucleus does not go, its task - only to preserve the genetic code and give it to daughter cell during division.
Summary table of the main participants in the broadcast
To describe the protein biosynthesis briefly and clearly, the table is a must.In it we will record all of the components and their role in this process, which is called translation.
What is necessary for the synthesis of
What role does
serve as a building material for the protein chain
is the venue broadcast
Transports amino acids to the ribosomes
delivered to the site of synthesis of information on the sequence of amino acids in a protein
very same process of creating a protein chain is divided into three stages.Let's look at each of these in more detail.Then you can easily explain to everyone protein biosynthesis brief and clear.
Initiation - the beginning of the process
This is the initial stage of the broadcast, in which the small subunit of the ribosome is connected with the first tRNA.This RNA carries the amino acid - methionine.Broadcast always starts with this amino acid, as is the start codon AUG, which encodes the first monomer in the protein chain.
In order to recognize the ribosome start codon and start from the middle of the gene synthesis, where the sequence AUG also may be around the start codon is a special sequence of nucleotides.It is for him the ribosome recognizes the place that it should take small subunit.
After the formation of the complex with m-RNA initiation stage ends.And it starts the main stage of the broadcast.
Elongation - mid synthesis
At this stage, there is a gradual build-up of protein chains.The duration of the elongation depends on the number of amino acids in the protein.
first step to the small ribosomal subunit joins big.And initial tRNA appears in it entirety.Outside, there is only methionine.Further, the large subunit enters second tRNA carrying a different amino acid.
If the second codon on the mRNA coincides with anticodon on top "cloverleaf", the second amino acid is attached to the first via a peptide bond.
Thereafter, the ribosome moves along the mRNA exactly three nucleotides (one codon), the first tRNA detaches itself from methionine and is separated from the complex.In its place is a second m-RNA at the end of which the hanging has two amino acids.
then included in the large subunit third tRNA and the process repeats.It will be up until it hits a ribosome codon in the mRNA, which signals the end of transmission.
This stage is the last, to some it may seem cruel.All molecules and organelles that are so consistently worked to create a polypeptide chain, stop as soon as the ribosome encounters a termination codon.
He does not encode any of the amino acid, so whatever tRNA or went into the large subunit, they will all be rejected because of the mismatch.Here come the cause termination factors that separate the protein from the ribosome ready.
itself organelle can either break up into two subunits, or to continue their journey on the m-RNA in search of a new start codon.In one mRNA may be several ribosomes.Each of them - on a stage translyatsii.Tolko created protein markers is provided, by which all will be understood by its destination.And it will be sent to CSE where necessary.
To understand the role of protein biosynthesis, it is necessary to examine what functions it can perform.This depends on the sequence of amino acids in the chain.It is their properties determine the secondary, tertiary and sometimes quaternary (if it exists) the structure of the protein and its role in the cell.For more information about the functions of protein molecules can be found in the article on this topic.
How to learn more about a broadcast
This article describes the biosynthesis of proteins in living cells.Of course, if you study the subject more deeply, to explain the process in detail will leave a lot of pages.However, the above material should be enough for general predstavleniya.Ochen useful for understanding may be video, in which scientists have simulated all stages of translation.Some of them have been translated into Russian, and can serve as an excellent tool for students or just informative video.
In order to understand the subject better, you should read the other articles on related topics.For example, nucleic acids, or about about protein function.