It is known as protein synthesis to the process by which new consist proteins from the twenty essential amino acids . In this process, DNA is transcribed into RNA . Protein synthesis is performed on ribosomes located in the cell cytoplasm .
In the synthesis process, amino acids are transported by corresponding transfer RNA for each amino acid to messenger RNA where they bind in the proper position to form the new proteins.
At the end of the synthesis of a protein, the messenger RNA is released and can be read again, even before the synthesis of a protein ends, the next one can begin, therefore, the same messenger RNA can be used by several ribosomes at the same time.
Below you can see more information about what is the process of protein synthesis, what are its phases and the steps that are carried out in each phase of protein synthesis.
Summary
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- 1 Phases of protein synthesis
- 2 Amino acid activation phase
- 3 Initiation of protein synthesis
- 4 Elongation of the polypeptide chain
- 5 Completion of protein synthesis
- 6 Sources
Phases of protein synthesis
- The performance of protein biosynthesis is divided into the following phases:
- Amino acid activation phase.
Translation phase comprising:
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- Beginning of protein synthesis.
- Elongation of the polypeptide chain.
- Completion of protein synthesis.
- Association of polypeptide chains and, in some cases, prosthetic groups for the constitution of proteins.
Amino acid activation phase
Through the enzyme aminoacyl-tRNA synthetase and ATP, amino acids can bind transfer-specific RNA, giving rise to an aminoacyl-tRNA. In this process, AMP and phosphate are released and after it, the enzyme is released, which acts again.
Start of protein synthesis
In this first stage of protein synthesis, RNA binds to the minor subunit of ribosomes, to which aminoacyl-tRNA is associated. To this group, the larger ribosomal subunit is attached, thereby forming the active or ribosomal complex.
Elongation of the polypeptide chain
The ribosomal complex has two centers or junction points. The P-center or peptidyl-center and the A-center. The amino radical of the initiated amino acid and the above carboxyl radical are linked by a peptide bond and this binding is catalyzed by the enzyme peptidyl transferase.
In this way, the P center is occupied by a tRNA lacking amino acid. Next, the tRNA is released from the ribosome, producing the ribosomal translocation and leaving the dipeptil-tRNA in the P center.
At the end of the third codon, the third aminoacyl-tRNA is located in center A. Next, tripeptide A is formed and then the ribosome proceeds to its second translocation. This process can be repeated many times and depends on the number of amino acids involved in the synthesis.
Completion of protein synthesis
At the completion of protein synthesis, so-called nonsense triplets appear, also known as stop codons. These triplets are three: UGA, UAG and UAA. There is no such tRNA that its anticodon is complementary. Therefore, the synthesis is interrupted and this indicates that the polypeptide chain has ended.