Abstrait

Protein synthesis and Transcription and Translation

Dr. Abhaya Raj

Protein synthesis is the complex biological process by which cells builds proteins, the fundamental building blocks of life. This process is essential for the growth, maintenance, and repair of living organisms, and involves a precise sequence of events that must occur in a specific order. The process of protein synthesis begins with the transcription of DNA, the genetic material that stores the instructions for making proteins, into messenger RNA (mRNA). This process takes place in the nucleus of the cell, where an enzyme called RNA polymerase reads the DNA sequence and synthesizes a complementary mRNA strand. The mRNA molecule then travels from the nucleus to the cytoplasm of the cell, where it encounters ribosomes, the cellular structures responsible for translating the genetic code into proteins. Ribosomes consist of two subunits, each made up of RNA and protein molecules. The process of translation begins with the binding of the mRNA molecule to the small ribosomal subunit. The ribosome then scans the mRNA molecule until it encounters a start codon, which signals the beginning of the protein-coding sequence. Next, transfer RNA (tRNA) molecules, which are specific to each amino acid, carry the amino acids to the ribosome. Each tRNA molecule contains an anticodon, which matches the codon on the mRNA, as well as a binding site for the corresponding amino acid. As the ribosome moves along the mRNA molecule, it brings the appropriate tRNA molecule into position so that the anticodon on the tRNA cans base-pair with the codon on the mRNA. The ribosome then catalyzes the formation of a peptide bond between the amino acids carried by the adjacent tRNA molecules.