Protein synthesis in the cell - description, process functions
Proteins play a very important role in the vital activity of organisms, perform protective, structural, hormonal, energy functions. Provides muscle and bone growth. Proteins are informed about its functions and biochemical properties, they are part of valuable, healthy foods (eggs, dairy products, fish, nuts, legumes, rye and wheat). The digestibility of such food is due to biological value. With an equal amount of protein, it will be easier to digest the product whose value is higher. Defective polymers must be removed from the body and replaced with new ones. This process takes place during the synthesis of proteins in cells.
What are the proteins
Substances consisting only of amino acid residues are called simple proteins (proteins). If necessary, their energetic property is used, therefore, people leading a healthy lifestyle often additionally need protein intake.Complex proteins, proteids, are composed of simple protein and non-protein part. Ten amino acids in the protein are indispensable, which means that the body cannot synthesize them independently, they come from food, and another ten are replaceable, that is, they can be created from other amino acids. So begins the process vital for all organisms.
The main stages of biosynthesis: where do proteins come from
New molecules are taken as a result of biosynthesis - a chemical reaction of the compound. There are two main stages of the synthesis of proteins in the cell. This is a transcription and translation. Transcription occurs in the core. This is a reading from DNA (deoxyribonucleic acid), which carries information about the future protein, to RNA (ribonucleic acid), which transfers this information from DNA to the cytoplasm. This happens due to the fact that DNA does not participate directly in the biosynthesis, it only carries information without having the ability to exit into the cytoplasm, where protein is synthesized, and performing only the function of a carrier of genetic information. Transcription, on the other hand, makes it possible to read data from the DNA matrix onto RNA according to the principle of complementarity.
The role of RNA and DNA in the process
So, starts the synthesis of proteins in the cells of the DNA chain, which carries information about any particular protein and is called the gene. The DNA chain in the process of transcription unravels, that is, its helix begins to disintegrate into a linear molecule. With DNA, the information must be transformed into RNA. On the contrary thymine in this process should become adenine. Cytosine also has guanine as a pair, just like DNA. On the contrary, adenine RNA becomes uracil, because there is no such nucleotide as thymine in RNA, it is replaced with just a uracil nucleotide. Cytosine is adjacent to guanine. Opposite adenine becomes uracil, and adenine is located in a pair with thymine. These RNA molecules, which are the opposite, are called messenger RNA (mRNA). They are able through the pores to exit from the nucleus into the cytoplasm and the ribosomes, which, in fact, perform the function of protein synthesis in cells.
About complex simple words
Now the assembly is made from the amino acid sequences of the polypeptide chain of the protein. Transcription can be called reading information about the future of the protein from the DNA template to RNA.This can be defined as the first stage. After RNA leaves the nucleus, it must reach the ribosomes, where the second stage, called translation, occurs.
Translation is already an RNA transition, that is, the transfer of information from nucleotides to a protein molecule, when RNA indicates which sequence of amino acids should be in a substance. In this order, messenger RNA enters the cytoplasm of ribosomes that carry out the synthesis of proteins in the cell: A (adenine) - G (guanine) - U (uracil) - C (cytosine) - U (uracil) - A (adenine).
Why do we need ribosomes
In order for the translation to occur and as a result, a protein is formed, we need components such as the informational RNA itself, transport RNA, and also the ribosomes as the “factory” at which the protein is produced. In this case, two types of RNA are functioning: informational, which was formed in the nucleus with DNA, and transport. The molecule of the second acid has the form of clover. This "clover" attaches an amino acid to itself and carries it to the ribosomes. That is, he performs transportation of organic compounds directly to the "factory" on their education.
How rRNA works
There are also ribosomal RNAs that are part of the ribosome itself and perform protein synthesis in the cell. It turns out that ribosomes are non-membrane structures, they do not have shells, such as, for example, the nucleus or the endoplasmic reticulum, but consist simply of proteins and ribosomal RNA. What happens when a sequence of nucleotides, that is, messenger RNA, gets to the ribosomes?
Transport RNA, which is located in the cytoplasm, pulls amino acids to itself. Where did the amino acids in the cell come from? And they are formed as a result of the breakdown of proteins that are ingested with food. These compounds are carried by the bloodstream to the cells, where the production of proteins necessary for the body occurs.
The final stage of protein synthesis in cells
Amino acids float in the cytoplasm in the same way as transport RNAs, and when the polypeptide chain is assembled directly, these transport RNAs begin to connect with them. However, not in any sequence and not every transport RNA can connect with all kinds of amino acids. There is a certain site to which the necessary amino acid joins. The second section of transport RNA is called an anticodon.This element consists of three nucleotides that are complementary to the sequence of nucleotides in the messenger RNA. Three amino acids are required for one amino acid. For example, any conditional protein consists of just two amino acids for simplicity. Obviously, mostly proteins have a very long structure, composed of many amino acids. Chain A - G - Y is called a triplet, or a codon, a transport RNA will be added to it in the form of a clover, at the end of which there will be a certain amino acid. The next triplet C - Y - A will be joined by another tRNA, which will contain a completely different amino acid complementary to the sequence. In this order, further polypeptide chain assembly will occur.
Biological significance of synthesis
A peptide bond is formed between two amino acids located at the ends of the "clovers" of each triplet. At this stage, transport RNA leaves the cytoplasm. The following transport RNA with another amino acid, which forms a polypeptide chain with the previous two, is then added to the triplets.This process is repeated until the moment when the necessary sequence of amino acids is typed. Thus, protein synthesis occurs in the cell, and enzymes, hormones, blood substances, etc. are formed. Any protein is not formed in any cell. Each cell can form a specific protein. For example, in erythrocytes hemoglobin will be formed, and pancreatic cells will synthesize hormones and various enzymes that break down food that enters the body.
In the muscles, protein actin and myosin will be produced. As can be seen, the process of protein synthesis in cells is multi-step and complex, which indicates its importance and necessity for all living things.